https://www.causeweb.org/wiki/chance/api.php?action=feedcontributions&user=Thekohser&feedformat=atomChanceWiki - User contributions [en]2024-03-29T07:48:36ZUser contributionsMediaWiki 1.40.0-alphahttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_67&diff=11385Chance News 672010-11-01T21:02:07Z<p>Thekohser: /* Racial disparity in Wikimedia Commons photos */ typo</p>
<hr />
<div>==Quotations==<br />
<blockquote>“Next time someone tells you they don’t believe a small sample poll can possibly tell you anything, just say to them ‘OK, then. Next time you have to have a blood test, why don’t you ask them to take the whole lot?’”</blockquote><br />
<div align=right>British opinion pollster Nick Moon<br><br />
in <i>Significance</i>, March 2010<br></div align=right><br />
<br />
Submitted by Margaret Cibes<br />
----<br />
<blockquote>”The greater the number of scores in a sport, the lower the chance for a lucky win by a team that is inferior. …. A sport should have enough scoring—but no more than enough scoring—so that (a) a team that, in a large sample of games, tends to lose to most everyone usually doesn't beat a team that tends to beat everyone, and (b) any one player error or referee call typically will not change the outcome. On this basis, it seems, soccer and hockey have too few scores, basketball and tennis have too many, and baseball and American football are somewhere near the sweet spot.”</blockquote><br />
<div align=right>Richard Bookstaber, in [http://online.wsj.com/article/SB10001424052748704111704575354881568117558.html?KEYWORDS=richard+bookstaber “The Scoring Problem”]<br><br />
<i>The Wall Street Journal</i>, July 10, 2010<br></div align=right><br />
Submitted by Margaret Cibes<br />
----<br />
<blockquote>"In listening to stories we tend to suspend disbelief in order to be entertained, whereas in evaluating statistics we generally have an opposite inclination to suspend belief in order not to be beguiled."</blockquote><br />
<br />
<div align=right>John Allen Paulos, in [http://opinionator.blogs.nytimes.com/2010/10/24/stories-vs-statistics/ Stories vs. statistics] <br>''New York Times'', 24 October 2010<br />
</div align=right><br />
Submitted by Bill Peterson<br />
----<br />
From two letters to the editor:<br />
<blockquote>“Pie charts should only be used for showing data to children and politicians … three dimensional pie charts should not even be shown to politicians or children.”<br><br />
<br />
<br />
“Drawing up Happy Planet Indexes is an amusing academic activity. But just as you can’t fatten a pig by constantly weighing it, calculating ever more complex indexes won’t change much.”</blockquote><br />
<br />
<div align=right><i>Significance</i>, March 2010</div align=right><br />
<br />
Submitted by Margaret Cibes<br />
----<br />
Or is this next one perhaps a Forsooth...?<br />
<br />
<blockquote><br />
"How much math do you really need in everyday life? Ask yourself that -- and also the next 10 people you meet, say, your plumber, your lawyer, your grocer, your mechanic, your physician or even a math teacher.<br />
</blockquote><br />
<blockquote><br />
"Unlike literature, history, politics and music, math has little relevance to everyday life. That courses such as 'Quantitative Reasoning' improve critical thinking is an unsubstantiated myth. All the mathematics one needs in real life can be learned in early years without much fuss. Most adults have no contact with math at work, nor do they curl up with an algebra book for relaxation."<br />
</blockquote><br />
<div align=right>G.V. Ramanathan, [http://www.washingtonpost.com/wp-dyn/content/article/2010/10/22/AR2010102205451.html How much math do we really need?]<br><br />
''Washington Post'', 23 October 2010<br />
</div align=right><br />
Submitted by Paul Alper<br />
<br />
==Forsooth==<br />
An article describes two brands of athletic wear that are claimed to optimize performance via embedded holograms (Power Balance) and water-soluble titanium (Phiten).<br />
<blockquote>“A lot of these products are a sort of merchandized superstition. …. [A French surfer states,] ‘But if wearing the thing makes you think you feel or perform better, who cares?’”<br><br />
<div align="right"><br />
[http://www.time.com/time/magazine/article/0,9171,2021057,00.html “Wrist Watch”], <i>TIME</i>, October 4, 2010<br />
</div><br />
</blockquote><br />
Submitted by Margaret Cibes<br />
<br />
-----<br />
<blockquote>"A scant 1,391 people live in 91008 ZIP code, and only 12 homes are currently on the market. So a single high-priced listing (like the mammoth nine-bedroom, built this year, that's selling for $19.8 million) is enough to skew the median price skyward."<br><br />
<div align="right">[http://realestate.yahoo.com/promo/americas-most-expensive-zip-codes-2010.html America’s Most Expensive ZIP Codes 2010], <br><i>Yahoo! Real Estate</i>, September 27, 2010<br />
</div></blockquote><br />
Note that someone at Forbes must have spotted the potential error in the last 8 words. While the original sentence remains on the Yahoo website, the sentence now ends “may not adequately represent how everyone in the area lives” at the Forbes website[http://www.forbes.com/2010/09/27/most-expensive-zip-codes-2010-lifestyle-real-estate-zip-codes-10-intro.html].<br><br />
<br />
Submitted by Margaret Cibes at the suggestion of Cris Wellington<br />
<br />
----<br />
<blockquote><br />
"The relationship between an area's income and mortality is so striking," the report says, "that on average, every $10,000 increase in an area's median income appears to buy its residents another year of life."<br />
<br><br />
<div align="right"> <br />
[http://www.startribune.com/lifestyle/health/104540289.html?elr=KArksLckD8EQDUoaEyqyP4O:DW3ckUiD3aPc:_Yyc:aUUs Key to long life? It may be in ... your ZIP code]<br>Minneapolis Star Tribune, 7 October 2010 </div><br />
</blockquote><br />
<br />
Submitted by Paul Alper<br />
<br />
----<br />
Denmark’s prime minister, addressing a preliminary session of the 2009 Copenhagen Climate Conference:<br />
<br />
<blockquote> “Don’t provide us with too many moving targets, because it is already a very very complicated process. I need fixed targets, and figures that are certain, and not too many considerations of uncertainty and risk and things like that.”</blockquote><br />
<br />
<div align=right>Quoted in <i>Significance</i>, March 2010</div align=right><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==More fuel to feed the fiery controversy over mammograms==<br />
<br />
[http://www.nytimes.com/2010/09/30/health/research/30mammogram.html Mammogram Benefit Seen for Women in Their 40s], Gina Kolata, The New York Times, September 29, 2010.<br />
<br />
One of the most contentious debates in medicine is whether mammograms are beneficial to women between 40 and 50 years old. Earlier commentaries about this controversy appear in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_8#Mammograms_Validated_as_Key_in_Cancer_Fight Chance News 8], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_12#Screening Chance News 12], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_14#Gerd_Gigerenzer.27s_Calculated_Risks_Revisited Chance News 14], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_47#Bayes_theorem_in_the_news Chance News 47], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_58#Mammogram_Math Chance News 58], and [http://www.causeweb.org/wiki/chance/index.php/Chance_News_59#Ill_health_news Chance News 59].<br />
<br />
The first sentence in the latest article about mammography makes a bold claim...<br />
<br />
<blockquote>Researchers reported Wednesday that mammograms can cut the breast cancer death rate by 26 percent for women in their 40s.</blockquote><br />
<br />
...and the second sentence contradicts this claim.<br />
<br />
<blockquote>But their results were greeted with skepticism by some experts who say they may have overestimated the benefit.</blockquote><br />
<br />
The data set on which these bold claims were based is quite good.<br />
<br />
<blockquote>The new study took advantage of circumstances in Sweden, where since 1986 some counties have offered mammograms to women in their 40s and others have not, according to the lead author, Hakan Jonsson, professor of cancer epidemiology at Umea University in Sweden. The researchers compared breast cancer deaths in women who had a breast cancer diagnosis in counties that had screening with deaths in counties that did not. The rate was 26 percent lower in counties with screening.</blockquote><br />
<br />
Why the skepticism?<br />
<br />
<blockquote>One problem, said Dr. Peter C. Gotzsche of the Nordic Cochrane Center in Copenhagen, a nonprofit group that reviews health care research, is that the investigators counted the number of women who received a diagnosis of breast cancer and also died of it. They did not compare the broader breast cancer death rates in the counties.</blockquote><br />
<br />
A prominent statistician, Donald Berry, is also quoted in this article.<br />
<br />
===Questions===<br />
<br />
1. The research design in the current study was not randomized. Is this an issue?<br />
<br />
2. What are the barriers to conducting a randomized trial for mammography?<br />
<br />
==Even more fuel!==<br />
[http://www.healthnewsreview.org/blog/2010/10/this-is-the-way-the-swedish-mammography-study-couldshould-have-been-analyzed.html This is the way the Swedish mammography study could/should have been analyzed]<br><br />
by Gary Schwitzer, HealthNewsReview Blog, 4 October 2010<br />
<br />
Schwitzer's blog (which we first mentioned in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_59#Ill_health_news Chance News 59]) discusses news reports on public health issues, rating the stories according to a set [http://www.healthnewsreview.org/review-criteria.php rubric]. <br />
<br />
His present post concerns the Swedish mammogram study. He reviews the New York Times article described above, as well as reports from the <br />
[http://articles.latimes.com/2010/sep/29/news/la-heb-mammography-20100929 Los Angeles Times], the <br />
[http://www.npr.org/templates/story/story.php?storyId=130053888 Associated Press] and <br />
[http://news.health.com/2010/09/29/mammograms-save-lives-for-women-in-their-40s-study-says/ Health Day]. The last is singled out as the only one of the four that fails to make any mention of methodological concerns. However, Schwitzer goes on to argue that none of the articles does an adequate job explaining the methodological issues or their implications for the conclusions of the study. Read the full post for an interesting extended discussion on this.<br />
<br />
'''Question'''<br><br />
<br />
The discussion in the post notwithstanding, the individual HealthNewsReview ratings cited there give the [http://www.healthnewsreview.org/review.html?review_id=3203 NYT], <br />
the [http://www.healthnewsreview.org/review.html?review_id=3204 LA Times] <br />
and [http://www.healthnewsreview.org/review.html?review_id=3205 AP] <br />
stories 4 stars, 5 stars, and 5 stars (out of 5) respectively. What do you make of this?<br />
<br />
Submitted by Bill Peterson<br />
<br />
==Proofiness==<br />
<br />
Charles Seife is a marvelous writer of serious, interesting topics for the lay reader:<br />
<ul><br />
<li>''Zero: The Biography of a Dangerous Idea'', 2000<br />
<li>''Alpha & Omega: The Search for the Beginning and End of the Universe'', 2004<br />
<li>''Decoding The Universe'', 2007<br />
<li>''Sun in a Bottle: The Strange History of Fusion and the Science of Wishful Thinking'', 2008<br />
</ul><br />
His latest book, ''Proofiness: The Dark Arts of Mathematical Deception'', 2010, makes for especially good reading for students and teachers of statistics. The following web sites all comment on the book: The New York Times has a [http://www.nytimes.com/2010/09/19/books/review/Strogatz-t.html?_r=1&ref=bookreviews review] and an [http://www.nytimes.com/2010/09/16/books/excerpt-proofiness.html?ref=review excerpt]; NPR ran a story, [http://www.npr.org/templates/story/story.php?storyId=129972868 Lies, Damned Lies, And 'Proofiness']; additional reviews appeared<br />
in [http://www.nyjournalofbooks.com/2010/09/proofiness-dark-arts-of-mathematical.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+NewYorkJournalOfBooks+(NEW+YORK+JOURNAL+OF+BOOKS) New York Journal of Books] and [http://www.politicsdaily.com/2010/08/01/proofiness-using-numbers-to-fool-people-and-shape-political-deb/ Politics Daily].<br />
<br />
The reviews are entirely favorable, but don’t quite do justice to his presentation, so readers of Chance News are encouraged to read the book as well as the above commentaries.<br />
<br />
Seife defines proofiness as “the art of using bogus mathematical arguments to prove something that you know in your heart is true — even when it’s not.” However, he never makes the connection to [http://www.innumeracy.com/ Innumeracy] <br />
<blockquote><br />
A term meant to convey a person's inability to make sense of the numbers that run their lives. Innumeracy was coined by cognitive scientist Douglas R Hofstadter in one of his Metamagical Thema columns for Scientific American in the early nineteen eighties. Later that decade mathematician John Allen Paulos published the book Innumeracy. In it he includes the notion of chance as well to that of numbers.<br />
</blockquote><br />
Seife also does not refer to Stephen Colbert’s even more famous neologism, [http://en.wikipedia.org/wiki/Truthiness truthiness] which<br />
<br />
<blockquote><br />
is a "truth" that a person claims to know intuitively "from the gut" without regard to evidence, logic, intellectual examination, or facts.<br />
</blockquote><br />
<br />
Colbert himself put truthiness this way:<br />
"We're not talking about truth, we're talking about something that seems like truth – the truth we want to exist."<br />
<br />
Seife begins his Introduction with the famous quotation of Senator Joseph McCarthy on February 9, 1950:<br />
<br />
<blockquote><br />
"I have here in my hand a list of 205--a list of names that were made known to the Secretary of State as being members of the Communist party and who nevertheless are still working and shaping policy in the State Department."<br />
<blockquote><br />
</blockquote><br />
The 205 later became 57 and then 81. “It really didn’t matter whether the list had 205 or 57 or 81 names. The very fact that McCarthy had attached a number to his accusations imbued them with an aura of truth.” This “outrageous falsehood was given the appearance of absolute fact.”<br />
</blockquote><br />
<br />
Seife attempts to categorize the types of proofiness:<br />
<br />
A. Potemkin numbers--numerical facades that look like real numbers such as crowd estimates or the number of communists in the State Department.<br><br />
B. Disestimation, another neologism--“the act of taking a number too literally, understating or ignoring the uncertainties that surround it.”<br><br />
C. Fruit packing--“it’s not the individual numbers that are false; it is the presentation of the data that creates the proofiness.”<br><br />
D. Cherry picking--a form of fruit packing in which there is a “careful selection of data, choosing those that support the argument you wish to make while underplaying or ignoring data that undermine it.”<br><br />
E. Apples to oranges comparison--another form of fruit packing, for example, comparing dollar amounts without taking into account inflation.<br><br />
F. Apple polishing--another form of fruit packing, for example, deceptive graphs where the origin is missing; or, algebraically, misuse of mean and median.<br><br />
G. Causuistry, another neologism and a pun on the word casuistry--“a specialized form of casuistry where the fault in the argument comes from implying that there is a causal relationship between two things when in fact there isn’t any such linkage.”<br><br />
H. Randumbness, another neologism--“insisting that there is order where there is only chaos” or, “creating a pattern where there is none to see.”<br><br />
I. Regression to the moon--for example, extrapolating instead of interpolating regression results.<br><br />
<br />
None of these categories are new to teachers of statistics but his examples of the above forms of proofiness are detailed and when not frightening, are amusing; these examples include: the O.J. Simpson trial; the Franken-Coleman Minnesota Senate election and Bush vs. Gore in 2000 (he terms them “electile dysfunctions”); nuclear testing; risk analysis; the space program; the Vietnam war; and, determination of the perfect butt (page 66 contains the formula for callipygianness--a word which is '''not''' a neologism). He is particularly incisive when he discusses systematic error when it overwhelms and confuses the notion of error due to sampling, and thus, invalidating the so-called margin of error in polling. <br />
<br />
===Discussion===<br />
<br />
1. If it is so obvious today that McCarthy was fabricating the numbers -- in the parlance of today, he was fact-free -- why was he so successful so long in the 1950s? And why did his allegations and point of view live on well after his death in 1957?<br />
<br />
2. Seife devotes a great deal of time to convince the reader that the U.S. census would be more accurate if it did not attempt to count everyone but rather did statistical sampling and avoid many of the systematic errors. Why would this be true? Why did the U.S. Supreme Court deem otherwise?<br />
<br />
3. Some of his strongest criticism is directed at journalists and polling organizations. The chapter entitled, “Poll Cats.” On page 120 he says, “Internet polls have no basis in reality whatsoever.” Why? “Yet, CNN.com has an Internet poll on its front page every day.” Again, why? Non Internet polls do not come off much better due to flagrant non-statistical faults.<br />
<br />
4. With regard to the O.J. Simpson murder trial, Seife paraphrases one of Simpson's defense attorney's claim that “only one in a thousand wife-beaters winds up murdering his spouse. One in a thousand! Such a small probability means that O.J. Simpson almost certainly isn’t the murderer, right? “ Use Bayes theorem along with reasonable numbers about the number of wives being murdered to indicate that Simpson’s probability of being the culprit is much higher.<br />
<br />
5. Regression to the moon also refers to totally nonsensical use of regression. A more detailed look (page 66) at callipygianness reveals<br />
<center><br />
Callipygianness = (S + C) x (B + F) / (T - V) ,<br />
</center><br />
where S is shape, C is circularity, B is bounciness, F is firmness, T is texture, and V is waist-to-hip ratio. Seife found this regression result, not surprisingly, on <br />
[http://www.foxnews.com/story/0,2933,191622,00.html Fox News] and the reporter was from another Murdoch enterprise, The New York Post. Why does Seife find this regression result so ridiculous? On the same page, there is a regression result for “Misery” which depends upon weather, debt, motivation, “the need to take action,” and some other variables. “[I]t proved --scientifically--that the most miserable day of the year [2005] was January 24.” The regression result for “Happiness” appears on the preceding page. Why does Seife claim that these three are examples of Potemkin numbers?<br />
<br />
6. To return to McCarthy’s proofiness, his original speech about the 205 communists in the State Department was made in Wheeling, West Virginia to the Republican Women’s Club and made no waves whatsoever for days. Seife does not mention this, but only after the New York Times and the Washington Post publicized the speech did it ignite his fame. Contrast that time lag with today’s instant communication.<br />
<br />
7. Seife on page 226 repeats a famous adage of the journalism world: “If your mother says she loves you, check it out.” He then looks at the Pentagon’s weekly body counts and monthly hamlet evaluations during the Vietnam War. By page 228 he describes an auto-industry market research report which shows that driving a Hummer H3 is “better for the environment than driving the energy-efficient Toyota Prius hybrid.” Why did he juxtapose these two examples?<br />
<br />
8. The last paragraph of the book is: “Mathematical sophistication is the only antidote to proofiness and our degree of knowledge will determine whether we succumb to proofiness or fight against it. It’s more than mere rhetoric; our democracy may well rise or fall by the numbers.” Why might his “antidote” be insufficient?<br />
<br />
Submitted by Paul Alper<br />
<br />
==Sampling saliva==<br />
[http://www.thenation.com/article/154596/freshmen-specimen “Freshmen Specimen”]<br><br />
by Patricia J. Williams, <i>The Nation</i>, September 27, 2010<br> <br />
<br />
In this column, law professor Williams describes reactions to the University of California’s Berkeley project [http://onthesamepage.berkeley.edu/ “Bring Your Genes to Cal”], in which 5500 incoming freshmen were asked to provide saliva samples for the purpose of “bring[ing] the student body together in the same manner that reading To Kill a Mockingbird might have in the past.” More than 700 students submitted their samples to an uncertified Berkeley lab, and the samples were analyzed for “susceptibility to alcoholism, lactose intolerance and relative metabolism of folic acid.”<br><br />
<br />
<blockquote>[T]he California Department of Public Health barred the university from dispensing individual profiles on the grounds that genetic analysis is correlative only and is neither necessarily predictive nor diagnostic at this point. A collective comparison of the class's genetic data was permitted, however, and circulated in "anonymized" form at orientation.</blockquote><br />
<br />
Some ethical issues that have been raised include:<br><br />
(a) privacy, despite the “anonymizing” of results;<br><br />
(b) ownership of the data with respect to commercialization, patentability, remuneration, <i>etc.</i>;<br><br />
(c) promotion of the concept that a genetic correlation is a “100 percent infallible guarantee” of anything;<br><br />
(d) motive with respect to promoting sales of swab kits.<br><br />
<br />
The article refers to a Stanford University medical school class “spit party” and to a University of Minnesota [http://www.peds.umn.edu/gopherkids/ "Gopher Kids"] program (free gifts for saliva swabs at a state fair).<br />
<br />
Readers might be interested in a paper from ETC Group, a Canadian-based international organization, [http://www.etcgroup.org/upload/publication/675/02/genomixspitkits_03march08.pdf "Direct-to-Consumer DNA Testing and the Myth of Personalized Medicine: Spit Kits, SNP Chips and Human Genomics"]. Or they might want to google "spit party" to see how widespread these activities are.<br />
<br />
===Questions===<br />
<br />
1. Explain what the Public Health Department meant by the clause "genetic analysis is correlative only." <br />
<br />
2. Comment on the following statement in the article: “The university advertises participation as altruistic, a contribution to public health and human knowledge.”<br><br />
<br />
3. The author of the article refers to the process of collecting saliva samples as a “commodity exchange.” Do you agree with the author?<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Correlation as investment tool==<br />
[http://online.wsj.com/article/SB10001424052748704129204575505550134652416.html?KEYWORDS=jonnelle+marte “Why the Math of Correlation Matters”]<br><br />
by Jonnelle Marte, <i>The Wall Street Journal</i>, October 4, 2010<br><br />
<br />
This article discusses how a mutual-fund investor might employ the concept of correlation in aiming to diversify, and/or reduce volatility in, an investment portfolio. <br />
<br />
<blockquote>“If your investments move in lock step, or are highly correlated, "you'll either be all right or all wrong," says [an equity market strategist].</blockquote><br />
<br />
It describes how correlation is measured in comparing two investments: <br />
<blockquote>A correlation close to zero means the performance of one asset has little or no connection to that of the other. A correlation of 1 is a perfect positive correlation, meaning the two assets always move in sync—in the same direction, and at a scale that doesn't vary. For instance, Asset A will always move at twice the magnitude of Asset B. A correlation of minus 1 is a perfect negative correlation. The assets move in opposite directions at a scale that doesn't vary.</blockquote><br />
<br />
And it points out that daily, weekly, or monthly returns can be compared, and provides a table of correlations of various assets to the S&P 500 over a 10-year period. At the extremes are a +0.89 correlation between international stocks and the S&P, versus a -0.39 correlation between intermediate U.S. bonds and the S&P.<br> <br />
<br />
There are two caveats. The term of the analysis is a key consideration; for example, the 10-year correlation of -0.39 referred to above became a +0.08 correlation for an over-80-year period. Also, a crisis, such as the 2008 “crash,” may result in a “surge” in correlations, when investments of all kinds decreased.<br><br />
<br />
The author states that investors may choose assets that are uncorrelated, or negatively correlated, to the S&P 500, in order to balance, or minimize, risk.<br />
<blockquote>Such strategies are only recommended in the short term because they essentially cancel out returns. Holding too many negatively correlated assets can be a little like trying to hit the gas while slamming on the brakes, says [one financial analyst].</blockquote><br />
<br />
Interested readers are directed to the website [http://assetcorrelation.com "Asset Correlations"], where they will find a table of correlations between pairs of asset categories, or they may create their own tables.<br><br />
<br />
Two bloggers commented[http://online.wsj.com/article/SB10001424052748704129204575505550134652416.html?KEYWORDS=jonnelle+marte#articleTabs%3Dcomments]:<br><br />
<br />
(a) "This is NOT the way correlation works!!<br><br />
"A correlation of negative one does NOT mean that when asset class A returns 5%, asset class B returns negative 5%. It means that when asset class A returns greater than its expected return (say expected return of 5% and A is returning 7%), then asset class B will be return less than its expected return (if asset class B also has an expected return of 5%, then it would be returning 3%)."<br><br />
<br />
(b) "Good point. To summarize, correlation indicates if variables tend to move in the same direction, but gives no indication about the amplitude of these movements."<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Money isn’t everything, at least in baseball==<br />
[http://online.wsj.com/article/SB10001424052748703743504575493942146685242.html?KEYWORDS=matthew+futterman “The Year Money Didn’t Matter”]<br><br />
by Matthew Futterman, <i>The Wall Street Journal</i>, September 16, 2010<br><br />
<br />
This article reports that the correlation between Major League Baseball player payrolls and games won will be at its lowest level (0.14) since the 1994 players’ strike, if “current standings hold up through the end of the season.” And it contains a graph of correlations for the period 1995-2010 to date.<br><br />
<br />
http://sg.wsj.net/public/resources/images/WK-AV449_BASEBA_NS_20100916175614.gif<br />
<br />
While all eight teams reaching the playoffs had among the 10 top payrolls in 1999, only three of the highest payroll teams – but four of the lowest – will probably make the 2010 playoffs, if standings hold up through the end of this season.<br><br />
<br />
Despite the fact that top and bottom payrolls have grown farther apart in dollars, one factor in the current situation may be the 2002 revenue-sharing agreement, by which wealthier ball clubs now share increasing amounts of revenue with poorer clubs. Some of the revenue-receiving poorer teams have invested in non-payroll expenses such as scouting, trades, <i>etc</i>., with resulting improvements in performance, while some of the revenue-contributing teams’ performances have been constrained by long-term contracts with under-performing players, as well as by player injuries this year.<br><br />
See more data:<br><br />
(a) <i>Forbes</i> blog on 2010 baseball costs per win in [http://blogs.forbes.com/sportsmoney/2010/10/04/baseballs-most-and-least-efficient-teams-for-the-2010-season/ “Baseball’s Most and Least Efficient Teams for the 2010 Season”]<br><br />
(b) <i>New York Times</i> chart of payrolls vs. win-loss records over the period 2001-2010 in [http://www.nytimes.com/interactive/2010/09/26/sports/20090926-score-graphic.html “Putting a Price Tag on Winning”]<br><br />
(c) ESPN chart and table of payrolls vs. win-loss records over the period 1998-2008 in [http://sports.espn.go.com/espnmag/story?id=3816824 “The Biz: The Price of Winning”]<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Medical misinformation==<br />
[http://www.theatlantic.com/magazine/archive/2010/11/lies-damned-lies-and-medical-science/8269/ Lies, damned lies, and medical science]<br><br />
by David H. Freedman, ''The Atlantic'', November 2010<br />
<br />
This is a long essay on the work of Dr. John Ioannidis. A paper by Ionnidis, entitled <br />
[http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.0020124 Why most published research findings are false] was published in August 2005 in the Public Library of Science (PLoS) Medicine journal. John Gavin gave an excellent summary of this article in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_%28September-October_2005%29#Just_how_reliable_are_scientific_papers.3F Chance News 28]. <br />
<br />
One might imagine that raising serious reservations about the research enterprise might have made Ionnidis unpopular. However, the Atlantic article reports that, far from being ostracized by his colleagues, Ioannidis has become a much-sought-after speaker, and is a frequent co-author on research papers. His original PLoS article has become the most downloaded in the history of that journal.<br />
<br />
The article concludes with this quote from Ioannidis, which might serve as the moral of the story:<br />
<blockquote><br />
Science is a noble endeavor, but it’s also a low-yield endeavor. I’m not sure that more than a very small percentage of medical research is ever likely to lead to major improvements in clinical outcomes and quality of life. We should be very comfortable with that fact.<br />
</blockquote><br />
<br />
Submitted by Bill Peterson<br />
<br />
==World Statistics Day==<br />
<br />
See the U.S. Census Bureau website[http://www.census.gov/newsroom/releases/archives/news_conferences/2010-10-20_worldstats.html] for videos and other information related to the first World Statistics Day: October 20, 2010.<br> <br />
<br />
Note that the date, written in day/month/year format, is 20/10/2010. It will be interesting to see how the day is chosen in year 2013 or subsequent years.<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Racial disparity in Wikimedia Commons photos==<br />
<br />
A short article was [http://www.examiner.com/wiki-edits-in-national/racist-undertones-on-wikipedia published October 20] on Examiner.com, drawing attention to a racial disparity found in two distinct sections of freely-licensed visual content published at Wikimedia Commons (a sister site of Wikipedia). While the subject matter of the photos may make some uncomfortable, the parent Wikimedia Foundation did in fact [http://www.examiner.com/wiki-edits-in-national/wikimedia-foundation-rules-on-naughty-bits hire a consultant] to evaluate the situation from an independent perspective. <br />
<br />
What it boils down to is that the consultant said he evaluated 1,000 images of male sex organs that are found on Wikimedia Commons, and (by his count) not a single one was of a non-white male. In another (much smaller) category of photos and illustrations called "[http://commons.wikimedia.org/wiki/Category:Topless_adolescent_girls topless adolescent girls]", some 25 of the 26 images portray non-white subjects. <br />
<br />
As the Examiner article asks, is this a tacit form of racism? The odds that these two categories ''coincidentally'' ending up 99.9% white and 96.2% non-white, respectively, seem too hard to imagine.<br />
<br />
===Discussion===<br />
<br />
# What other factors might explain why a racial disparity is found in these categories?<br />
# Do you see any problematic factors in how a collection of encyclopedic images are gathered, when there is no editorial board guiding acquisition?<br />
<br />
Submitted by Gregory Kohs<br />
<br />
==Age has its rewards?== [http://online.wsj.com/article/SB10001424052748703545604575407242263991882.html?KEYWORDS=david+biderman “Trust the Wisdom of Older Managers”]<br><br />
by David Biderman, <i>The Wall Street Journal</i>, August 4, 2010<br><br />
<br />
The article provides a table of baseball managers’ age ranges and corresponding average winning percentages. Data is taken from the records of anyone who has managed since 2000 and has had a minimum of 5 years managing. There were 44 such managers over 539 seasons.<br><br />
<br />
Age: Average winning percentage<br><br />
35-37: 0.477<br><br />
38-40: 0.474<br><br />
41-43: 0.493<br><br />
44-46: 0.506<br><br />
47-49: 0.499<br><br />
50-52: 0.491<br><br />
53-55: 0.492<br><br />
56-58: 0.537<br><br />
59-61: 0.523<br><br />
62-64: 0.541<br><br />
65+: 0.515<br><br />
<br />
===Questions===<br />
<br />
1. How do you think that the author counted “539 seasons”?<br><br />
<br />
2. What is the average number of managers in each age category? Do you think that there would be enough managers in each age category to do a statistical comparison of the average winning percentages?<br><br />
<br />
3. The correlation between age and average winning percentage is about 0.8 (using age interval midpoints, and 70 for the oldest category). Suppose that you knew the average number of years managed for each age category. How would you expect its correlation with average winning percentage to compare to 0.8 – weaker, the same, stronger?<br><br />
<br />
4. Explain the author’s statements: “This idea that managers get better with age, though, might be somewhat self-fulfilling. Managers who perform poorly in their youth aren't able to drag down older managers' average[s] since they probably got canned.”<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Statisticians’ arithmetic==<br />
[http://www.nytimes.com/2010/10/17/opinion/17gilbert.html?_r=1&hp “Magic by Numbers”]<br><br />
by Daniel Gilbert, <i>The New York Times</i>, October 16, 2010<br><br />
<br />
The author cites a 2006 randomized double-blind study, [http://www.bmj.com/content/332/7554/1355.full/reply%232 “Effectiveness of discontinuing antibiotic treatment after three days instead of eight days in mild to moderate-severe community acquired pneumonia”]. The study concluded that the three-day period was "not inferior" to the eight-day period.<br><br />
<br />
A New Zealand medical student responded to the study with a number of criticisms[http://www.bmj.com/content/332/7554/1355.full/reply#2], including one about the researchers’ arithmetic: <br />
<blockquote>“In the per protocol analysis the cure rates were 93% (50/54) in the three day treatment group compared with 93% (56/60) in the eight day treatment group (difference 0.1% ….”</blockquote><br />
<br />
===Questions===<br />
1. Do you agree with the “difference” stated in the report?<br><br />
2. Can you suggest an arithmetic reason for the report’s 0.1% figure, assuming that it's not a typographical error?<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Crystal Ball Competition==<br />
The RSS and <i>Significance</i> magazine held their first Crystal Ball Competition in 2010. It consisted of 10 questions, asking for quantitative predictions about future events. Each answer was required to be both a number, and a standard deviation suggesting the accuracy of the number.<br><br />
<br />
The contest was open to anyone, including school and college teams, and the deadline for entries was May 28, 2010. The top prize was £200 and a year’s free membership in the RSS.<br> <br />
<br />
See [http://www.blackwellpublishing.com/pdf/crystal_ball_comp_2010.pdf “The 2010 Crystal Ball Competition”], [http://www.blackwellpublishing.com/pdf/crystal_ball_comp_2010_scoring.pdf “The RSS Crystal Ball 2010 scoring rule”], and [http://www.rssenews.org.uk/articles/20100731_6 “Crystal Ball competition – preliminary results”].<br />
<br />
A full report about the results of the contest will appear in the December 2010 issue of <i>Significance</i>.<br><br />
<br />
Submitted by Margaret Cibes</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_67&diff=11333Chance News 672010-10-22T15:44:45Z<p>Thekohser: /* Discussion */</p>
<hr />
<div>==Quotations==<br />
==Forsooth==<br />
An article describes two brands of athletic wear that are claimed to optimize performance via embedded holograms (Power Balance) and water-soluble titanium (Phiten).<br />
<blockquote>“A lot of these products are a sort of merchandized superstition. …. [A French surfer states,] ‘But if wearing the thing makes you think you feel or perform better, who cares?’”<br><br />
<div align="right"><br />
[http://www.time.com/time/magazine/article/0,9171,2021057,00.html “Wrist Watch”], <i>TIME</i>, October 4, 2010<br />
</div><br />
</blockquote><br />
Submitted by Margaret Cibes<br />
<br />
-----<br />
<blockquote>"A scant 1,391 people live in 91008 ZIP code, and only 12 homes are currently on the market. So a single high-priced listing (like the mammoth nine-bedroom, built this year, that's selling for $19.8 million) is enough to skew the median price skyward."<br><br />
<div align="right">[http://realestate.yahoo.com/promo/americas-most-expensive-zip-codes-2010.html America’s Most Expensive ZIP Codes 2010], <br><i>Yahoo! Real Estate</i>, September 27, 2010<br />
</div></blockquote><br />
Note that someone at Forbes must have spotted the potential error in the last 8 words. While the original sentence remains on the Yahoo website, the sentence now ends “may not adequately represent how everyone in the area lives” at the Forbes website[http://www.forbes.com/2010/09/27/most-expensive-zip-codes-2010-lifestyle-real-estate-zip-codes-10-intro.html].<br><br />
<br />
Submitted by Margaret Cibes at the suggestion of Cris Wellington<br />
<br />
----<br />
<blockquote><br />
"The relationship between an area's income and mortality is so striking," the report says, "that on average, every $10,000 increase in an area's median income appears to buy its residents another year of life."<br />
<br><br />
<div align="right"> <br />
[http://www.startribune.com/lifestyle/health/104540289.html?elr=KArksLckD8EQDUoaEyqyP4O:DW3ckUiD3aPc:_Yyc:aUUs Key to long life? It may be in ... your ZIP code]<br>Minneapolis Star Tribune, 7 October 2010 </div><br />
</blockquote><br />
<br />
Submitted by Paul Alper<br />
<br />
==More fuel to feed the fiery controversy over mammograms==<br />
<br />
[http://www.nytimes.com/2010/09/30/health/research/30mammogram.html Mammogram Benefit Seen for Women in Their 40s], Gina Kolata, The New York Times, September 29, 2010.<br />
<br />
One of the most contentious debates in medicine is whether mammograms are beneficial to women between 40 and 50 years old. Earlier commentaries about this controversy appear in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_8#Mammograms_Validated_as_Key_in_Cancer_Fight Chance News 8], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_12#Screening Chance News 12], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_14#Gerd_Gigerenzer.27s_Calculated_Risks_Revisited Chance News 14], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_47#Bayes_theorem_in_the_news Chance News 47], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_58#Mammogram_Math Chance News 58], and [http://www.causeweb.org/wiki/chance/index.php/Chance_News_59#Ill_health_news Chance News 59].<br />
<br />
The first sentence in the latest article about mammography makes a bold claim...<br />
<br />
<blockquote>Researchers reported Wednesday that mammograms can cut the breast cancer death rate by 26 percent for women in their 40s.</blockquote><br />
<br />
...and the second sentence contradicts this claim.<br />
<br />
<blockquote>But their results were greeted with skepticism by some experts who say they may have overestimated the benefit.</blockquote><br />
<br />
The data set on which these bold claims were based is quite good.<br />
<br />
<blockquote>The new study took advantage of circumstances in Sweden, where since 1986 some counties have offered mammograms to women in their 40s and others have not, according to the lead author, Hakan Jonsson, professor of cancer epidemiology at Umea University in Sweden. The researchers compared breast cancer deaths in women who had a breast cancer diagnosis in counties that had screening with deaths in counties that did not. The rate was 26 percent lower in counties with screening.</blockquote><br />
<br />
Why the skepticism?<br />
<br />
<blockquote>One problem, said Dr. Peter C. Gotzsche of the Nordic Cochrane Center in Copenhagen, a nonprofit group that reviews health care research, is that the investigators counted the number of women who received a diagnosis of breast cancer and also died of it. They did not compare the broader breast cancer death rates in the counties.</blockquote><br />
<br />
A prominent statistician, Donald Berry, is also quoted in this article.<br />
<br />
===Questions===<br />
<br />
1. The research design in the current study was not randomized. Is this an issue?<br />
<br />
2. What are the barriers to conducting a randomized trial for mammography?<br />
<br />
==Even more fuel!==<br />
[http://www.healthnewsreview.org/blog/2010/10/this-is-the-way-the-swedish-mammography-study-couldshould-have-been-analyzed.html This is the way the Swedish mammography study could/should have been analyzed]<br><br />
by Gary Schwitzer, HealthNewsReview Blog, 4 October 2010<br />
<br />
Schwitzer's blog (which we first mentioned in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_59#Ill_health_news Chance News 59]) discusses news reports on public health issues, rating the stories according to a set [http://www.healthnewsreview.org/review-criteria.php rubric]. <br />
<br />
His present post concerns the Swedish mammogram study. He reviews the New York Times article described above, as well as reports from the <br />
[http://articles.latimes.com/2010/sep/29/news/la-heb-mammography-20100929 Los Angeles Times], the <br />
[http://www.npr.org/templates/story/story.php?storyId=130053888 Associated Press] and <br />
[http://news.health.com/2010/09/29/mammograms-save-lives-for-women-in-their-40s-study-says/ Health Day]. The last is singled out as the only one of the four that fails to make any mention of methodological concerns. However, Schwitzer goes on to argue that none of the articles does an adequate job explaining the methodological issues or their implications for the conclusions of the study. Read the full post for an interesting extended discussion on this.<br />
<br />
'''Question'''<br><br />
<br />
The discussion in the post notwithstanding, the individual HealthNewsReview ratings cited there give the [http://www.healthnewsreview.org/review.html?review_id=3203 NYT], <br />
the [http://www.healthnewsreview.org/review.html?review_id=3204 LA Times] <br />
and [http://www.healthnewsreview.org/review.html?review_id=3205 AP] <br />
stories 4 stars, 5 stars, and 5 stars (out of 5) respectively. What do you make of this?<br />
<br />
Submitted by Bill Peterson<br />
<br />
==Proofiness==<br />
<br />
Charles Seife is a marvelous writer of serious, interesting topics for the lay reader:<br />
<ul><br />
<li>''Zero: The Biography of a Dangerous Idea'', 2000<br />
<li>''Alpha & Omega: The Search for the Beginning and End of the Universe'', 2004<br />
<li>''Decoding The Universe'', 2007<br />
<li>''Sun in a Bottle: The Strange History of Fusion and the Science of Wishful Thinking'', 2008<br />
</ul><br />
His latest book, ''Proofiness: The Dark Arts of Mathematical Deception'', 2010, makes for especially good reading for students and teachers of statistics. The following web sites all comment on the book: The New York Times has a [http://www.nytimes.com/2010/09/19/books/review/Strogatz-t.html?_r=1&ref=bookreviews review] and an [http://www.nytimes.com/2010/09/16/books/excerpt-proofiness.html?ref=review excerpt]; NPR ran a story, [http://www.npr.org/templates/story/story.php?storyId=129972868 Lies, Damned Lies, And 'Proofiness']; additional reviews appeared<br />
in [http://www.nyjournalofbooks.com/2010/09/proofiness-dark-arts-of-mathematical.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+NewYorkJournalOfBooks+(NEW+YORK+JOURNAL+OF+BOOKS) New York Journal of Books] and [http://www.politicsdaily.com/2010/08/01/proofiness-using-numbers-to-fool-people-and-shape-political-deb/ Politics Daily].<br />
<br />
The reviews are entirely favorable, but don’t quite do justice to his presentation, so readers of Chance News are encouraged to read the book as well as the above commentaries.<br />
<br />
Seife defines proofiness as “the art of using bogus mathematical arguments to prove something that you know in your heart is true — even when it’s not.” However, he never makes the connection to [http://www.innumeracy.com/ Innumeracy] <br />
<blockquote><br />
A term meant to convey a person's inability to make sense of the numbers that run their lives. Innumeracy was coined by cognitive scientist Douglas R Hofstadter in one of his Metamagical Thema columns for Scientific American in the early nineteen eighties. Later that decade mathematician John Allen Paulos published the book Innumeracy. In it he includes the notion of chance as well to that of numbers.<br />
</blockquote><br />
Seife also does not refer to Stephen Colbert’s even more famous neologism, [http://en.wikipedia.org/wiki/Truthiness truthiness] which<br />
<br />
<blockquote><br />
is a "truth" that a person claims to know intuitively "from the gut" without regard to evidence, logic, intellectual examination, or facts.<br />
</blockquote><br />
<br />
Colbert himself put truthiness this way:<br />
"We're not talking about truth, we're talking about something that seems like truth – the truth we want to exist."<br />
<br />
Seife begins his Introduction with the famous quotation of Senator Joseph McCarthy on February 9, 1950:<br />
<br />
<blockquote><br />
"I have here in my hand a list of 205--a list of names that were made known to the Secretary of State as being members of the Communist party and who nevertheless are still working and shaping policy in the State Department."<br />
<blockquote><br />
</blockquote><br />
The 205 later became 57 and then 81. “It really didn’t matter whether the list had 205 or 57 or 81 names. The very fact that McCarthy had attached a number to his accusations imbued them with an aura of truth.” This “outrageous falsehood was given the appearance of absolute fact.”<br />
</blockquote><br />
<br />
Seife attempts to categorize the types of proofiness:<br />
<br />
A. Potemkin numbers--numerical facades that look like real numbers such as crowd estimates or the number of communists in the State Department.<br><br />
B. Disestimation, another neologism--“the act of taking a number too literally, understating or ignoring the uncertainties that surround it.”<br><br />
C. Fruit packing--“it’s not the individual numbers that are false; it is the presentation of the data that creates the proofiness.”<br><br />
D. Cherry picking--a form of fruit packing in which there is a “careful selection of data, choosing those that support the argument you wish to make while underplaying or ignoring data that undermine it.”<br><br />
E. Apples to oranges comparison--another form of fruit packing, for example, comparing dollar amounts without taking into account inflation.<br><br />
F. Apple polishing--another form of fruit packing, for example, deceptive graphs where the origin is missing; or, algebraically, misuse of mean and median.<br><br />
G. Causuistry, another neologism and a pun on the word casuistry--“a specialized form of casuistry where the fault in the argument comes from implying that there is a causal relationship between two things when in fact there isn’t any such linkage.”<br><br />
H. Randumbness, another neologism--“insisting that there is order where there is only chaos” or, “creating a pattern where there is none to see.”<br><br />
I. Regression to the moon--for example, extrapolating instead of interpolating regression results.<br><br />
<br />
None of these categories are new to teachers of statistics but his examples of the above forms of proofiness are detailed and when not frightening, are amusing; these examples include: the O.J. Simpson trial; the Franken-Coleman Minnesota Senate election and Bush vs. Gore in 2000 (he terms them “electile dysfunctions”); nuclear testing; risk analysis; the space program; the Vietnam war; and, determination of the perfect butt (page 66 contains the formula for callipygianness--a word which is '''not''' a neologism). He is particularly incisive when he discusses systematic error when it overwhelms and confuses the notion of error due to sampling, and thus, invalidating the so-called margin of error in polling. <br />
<br />
===Discussion===<br />
<br />
1. If it is so obvious today that McCarthy was fabricating the numbers -- in the parlance of today, he was fact-free -- why was he so successful so long in the 1950s? And why did his allegations and point of view live on well after his death in 1957?<br />
<br />
2. Seife devotes a great deal of time to convince the reader that the U.S. census would be more accurate if it did not attempt to count everyone but rather did statistical sampling and avoid many of the systematic errors. Why would this be true? Why did the U.S. Supreme Court deem otherwise?<br />
<br />
3. Some of his strongest criticism is directed at journalists and polling organizations. The chapter entitled, “Poll Cats.” On page 120 he says, “Internet polls have no basis in reality whatsoever.” Why? “Yet, CNN.com has an Internet poll on its front page every day.” Again, why? Non Internet polls do not come off much better due to flagrant non-statistical faults.<br />
<br />
4. With regard to the O.J. Simpson murder trial, Seife paraphrases one of Simpson's defense attorney's claim that “only one in a thousand wife-beaters winds up murdering his spouse. One in a thousand! Such a small probability means that O.J. Simpson almost certainly isn’t the murderer, right? “ Use Bayes theorem along with reasonable numbers about the number of wives being murdered to indicate that Simpson’s probability of being the culprit is much higher.<br />
<br />
5. Regression to the moon also refers to totally nonsensical use of regression. A more detailed look (page 66) at callipygianness reveals<br />
<center><br />
Callipygianness = (S + C) x (B + F) / (T - V) ,<br />
</center><br />
where S is shape, C is circularity, B is bounciness, F is firmness, T is texture, and V is waist-to-hip ratio. Seife found this regression result, not surprisingly, on <br />
[http://www.foxnews.com/story/0,2933,191622,00.html Fox News] and the reporter was from another Murdoch enterprise, The New York Post. Why does Seife find this regression result so ridiculous? On the same page, there is a regression result for “Misery” which depends upon weather, debt, motivation, “the need to take action,” and some other variables. “[I]t proved --scientifically--that the most miserable day of the year [2005] was January 24.” The regression result for “Happiness” appears on the preceding page. Why does Seife claim that these three are examples of Potemkin numbers?<br />
<br />
6. To return to McCarthy’s proofiness, his original speech about the 205 communists in the State Department was made in Wheeling, West Virginia to the Republican Women’s Club and made no waves whatsoever for days. Seife does not mention this, but only after the New York Times and the Washington Post publicized the speech did it ignite his fame. Contrast that time lag with today’s instant communication.<br />
<br />
7. Seife on page 226 repeats a famous adage of the journalism world: “If your mother says she loves you, check it out.” He then looks at the Pentagon’s weekly body counts and monthly hamlet evaluations during the Vietnam War. By page 228 he describes an auto-industry market research report which shows that driving a Hummer H3 is “better for the environment than driving the energy-efficient Toyota Prius hybrid.” Why did he juxtapose these two examples?<br />
<br />
8. The last paragraph of the book is: “Mathematical sophistication is the only antidote to proofiness and our degree of knowledge will determine whether we succumb to proofiness or fight against it. It’s more than mere rhetoric; our democracy may well rise or fall by the numbers.” Why might his “antidote” be insufficient?<br />
<br />
Submitted by Paul Alper<br />
<br />
==Sampling saliva==<br />
[http://www.thenation.com/article/154596/freshmen-specimen “Freshmen Specimen”]<br><br />
by Patricia J. Williams, <i>The Nation</i>, September 27, 2010<br> <br />
<br />
In this column, law professor Williams describes reactions to the University of California’s Berkeley project [http://onthesamepage.berkeley.edu/ “Bring Your Genes to Cal”], in which 5500 incoming freshmen were asked to provide saliva samples for the purpose of “bring[ing] the student body together in the same manner that reading To Kill a Mockingbird might have in the past.” More than 700 students submitted their samples to an uncertified Berkeley lab, and the samples were analyzed for “susceptibility to alcoholism, lactose intolerance and relative metabolism of folic acid.”<br><br />
<br />
<blockquote>[T]he California Department of Public Health barred the university from dispensing individual profiles on the grounds that genetic analysis is correlative only and is neither necessarily predictive nor diagnostic at this point. A collective comparison of the class's genetic data was permitted, however, and circulated in "anonymized" form at orientation.</blockquote><br />
<br />
Some ethical issues that have been raised include:<br><br />
(a) privacy, despite the “anonymizing” of results;<br><br />
(b) ownership of the data with respect to commercialization, patentability, remuneration, <i>etc.</i>;<br><br />
(c) promotion of the concept that a genetic correlation is a “100 percent infallible guarantee” of anything;<br><br />
(d) motive with respect to promoting sales of swab kits.<br><br />
<br />
The article refers to a Stanford University medical school class “spit party” and to a University of Minnesota [http://www.peds.umn.edu/gopherkids/ "Gopher Kids"] program (free gifts for saliva swabs at a state fair).<br />
<br />
Readers might be interested in a paper from ETC Group, a Canadian-based international organization, [http://www.etcgroup.org/upload/publication/675/02/genomixspitkits_03march08.pdf "Direct-to-Consumer DNA Testing and the Myth of Personalized Medicine: Spit Kits, SNP Chips and Human Genomics"]. Or they might want to google "spit party" to see how widespread these activities are.<br />
<br />
===Discussion===<br />
<br />
1. Explain what the Public Health Department meant by the clause "genetic analysis is correlative only." <br />
<br />
2. Comment on the following statement in the article: “The university advertises participation as altruistic, a contribution to public health and human knowledge.”<br><br />
<br />
3. The author of the article refers to the process of collecting saliva samples as a “commodity exchange.” Do you agree with the author?<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Correlation as investment tool==<br />
[http://online.wsj.com/article/SB10001424052748704129204575505550134652416.html?KEYWORDS=jonnelle+marte “Why the Math of Correlation Matters”]<br><br />
by Jonnelle Marte, <i>The Wall Street Journal</i>, October 4, 2010<br><br />
<br />
This article discusses how a mutual-fund investor might employ the concept of correlation in aiming to diversify, and/or reduce volatility in, an investment portfolio. <br />
<br />
<blockquote>“If your investments move in lock step, or are highly correlated, "you'll either be all right or all wrong," says [an equity market strategist].</blockquote><br />
<br />
It describes how correlation is measured in comparing two investments: <br />
<blockquote>A correlation close to zero means the performance of one asset has little or no connection to that of the other. A correlation of 1 is a perfect positive correlation, meaning the two assets always move in sync—in the same direction, and at a scale that doesn't vary. For instance, Asset A will always move at twice the magnitude of Asset B. A correlation of minus 1 is a perfect negative correlation. The assets move in opposite directions at a scale that doesn't vary.</blockquote><br />
<br />
And it points out that daily, weekly, or monthly returns can be compared, and provides a table of correlations of various assets to the S&P 500 over a 10-year period. At the extremes are a +0.89 correlation between international stocks and the S&P, versus a -0.39 correlation between intermediate U.S. bonds and the S&P.<br> <br />
<br />
There are two caveats. The term of the analysis is a key consideration; for example, the 10-year correlation of -0.39 referred to above became a +0.08 correlation for an over-80-year period. Also, a crisis, such as the 2008 “crash,” may result in a “surge” in correlations, when investments of all kinds decreased.<br><br />
<br />
The author states that investors may choose assets that are uncorrelated, or negatively correlated, to the S&P 500, in order to balance, or minimize, risk.<br />
<blockquote>Such strategies are only recommended in the short term because they essentially cancel out returns. Holding too many negatively correlated assets can be a little like trying to hit the gas while slamming on the brakes, says [one financial analyst].</blockquote><br />
<br />
Interested readers are directed to the website [http://assetcorrelation.com "Asset Correlations"], where they will find a table of correlations between pairs of asset categories, or they may create their own tables.<br><br />
<br />
Two bloggers commented[http://online.wsj.com/article/SB10001424052748704129204575505550134652416.html?KEYWORDS=jonnelle+marte#articleTabs%3Dcomments]:<br><br />
<br />
(a) "This is NOT the way correlation works!!<br><br />
"A correlation of negative one does NOT mean that when asset class A returns 5%, asset class B returns negative 5%. It means that when asset class A returns greater than its expected return (say expected return of 5% and A is returning 7%), then asset class B will be return less than its expected return (if asset class B also has an expected return of 5%, then it would be returning 3%)."<br><br />
<br />
(b) "Good point. To summarize, correlation indicates if variables tend to move in the same direction, but gives no indication about the amplitude of these movements."<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Money isn’t everything, at least in baseball==<br />
[http://online.wsj.com/article/SB10001424052748703743504575493942146685242.html?KEYWORDS=matthew+futterman “The Year Money Didn’t Matter”]<br><br />
By Matthew Futterman, <i>The Wall Street Journal</i>, September 16, 2010<br><br />
<br />
This article reports that the correlation between Major League Baseball player payrolls and games won will be at its lowest level (0.14) since the 1994 players’ strike, if “current standings hold up through the end of the season.” And it contains a graph of correlations for the period 1995-2010 to date.<br><br />
<br />
http://sg.wsj.net/public/resources/images/WK-AV449_BASEBA_NS_20100916175614.gif<br />
<br />
While all eight teams reaching the playoffs had among the 10 top payrolls in 1999, only three of the highest payroll teams – but four of the lowest – will probably make the 2010 playoffs, if standings hold up through the end of this season.<br><br />
<br />
Despite the fact that top and bottom payrolls have grown farther apart in dollars, one factor in the current situation may be the 2002 revenue-sharing agreement, by which wealthier ball clubs now share increasing amounts of revenue with poorer clubs. Some of the revenue-receiving poorer teams have invested in non-payroll expenses such as scouting, trades, <i>etc</i>., with resulting improvements in performance, while some of the revenue-contributing teams’ performances have been constrained by long-term contracts with under-performing players, as well as by player injuries this year.<br><br />
See more data:<br><br />
(a) <i>Forbes</i> blog on 2010 baseball costs per win in [http://blogs.forbes.com/sportsmoney/2010/10/04/baseballs-most-and-least-efficient-teams-for-the-2010-season/ “Baseball’s Most and Least Efficient Teams for the 2010 Season”]<br><br />
(b) <i>New York Times</i> chart of payrolls vs. win-loss records over the period 2001-2010 in [http://www.nytimes.com/interactive/2010/09/26/sports/20090926-score-graphic.html “Putting a Price Tag on Winning”]<br><br />
(c) ESPN chart and table of payrolls vs. win-loss records over the period 1998-2008 in [http://sports.espn.go.com/espnmag/story?id=3816824 “The Biz: The Price of Winning”]<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Medical misinformation==<br />
[http://www.theatlantic.com/magazine/archive/2010/11/lies-damned-lies-and-medical-science/8269/ Lies, damned lies, and medical science]<br><br />
by David H. Freedman, ''The Atlantic'', November 2010<br />
<br />
To be continued...<br />
<br />
==World Statistics Day==<br />
<br />
See the U.S. Census Bureau website[http://www.census.gov/newsroom/releases/archives/news_conferences/2010-10-20_worldstats.html] for videos and other information related to the first World Statistics Day: October 20, 2010.<br> <br />
<br />
Note that the date, written in day/month/year format, is 20/10/2010. It will be interesting to see how the day is chosen in year 2013 or subsequent years.<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Racial disparity in Wikimedia Commons photos==<br />
<br />
A short article was [http://www.examiner.com/wiki-edits-in-national/racist-undertones-on-wikipedia published October 20] on Examiner.com, drawing attention to a racial disparity found in two distinct sections of freely-licensed visual content published at Wikimedia Commons (a sister site of Wikipedia). While the subject matter of the photos may make some uncomfortable, the parent Wikimedia Foundation did in fact [http://www.examiner.com/wiki-edits-in-national/wikimedia-foundation-rules-on-naughty-bits hire a consultant] to evaluate the situation from an independent perspective. <br />
<br />
What is boils down to is that the consultant said he evaluated 1,000 images of male sex organs that are found on Wikimedia Commons, and (by his count) not a single one was of a non-white male. In another (much smaller) category of photos and illustrations called "[http://commons.wikimedia.org/wiki/Category:Topless_adolescent_girls topless adolescent girls]", some 25 of the 26 images portray non-white subjects. <br />
<br />
As the Examiner article asks, is this a tacit form of racism? The odds that these two categories ''coincidentally'' ending up 99.9% white and 96.2% non-white, respectively, seem too hard to imagine.<br />
<br />
===Discussion===<br />
<br />
# What other factors might explain why a racial disparity is found in these categories?<br />
# Do you see any problematic factors in how a collection of encyclopedic images are gathered, when there is no editorial board guiding acquisition?<br />
<br />
Submitted by Gregory Kohs</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_67&diff=11332Chance News 672010-10-22T15:44:07Z<p>Thekohser: /* Discussion */ spacing</p>
<hr />
<div>==Quotations==<br />
==Forsooth==<br />
An article describes two brands of athletic wear that are claimed to optimize performance via embedded holograms (Power Balance) and water-soluble titanium (Phiten).<br />
<blockquote>“A lot of these products are a sort of merchandized superstition. …. [A French surfer states,] ‘But if wearing the thing makes you think you feel or perform better, who cares?’”<br><br />
<div align="right"><br />
[http://www.time.com/time/magazine/article/0,9171,2021057,00.html “Wrist Watch”], <i>TIME</i>, October 4, 2010<br />
</div><br />
</blockquote><br />
Submitted by Margaret Cibes<br />
<br />
-----<br />
<blockquote>"A scant 1,391 people live in 91008 ZIP code, and only 12 homes are currently on the market. So a single high-priced listing (like the mammoth nine-bedroom, built this year, that's selling for $19.8 million) is enough to skew the median price skyward."<br><br />
<div align="right">[http://realestate.yahoo.com/promo/americas-most-expensive-zip-codes-2010.html America’s Most Expensive ZIP Codes 2010], <br><i>Yahoo! Real Estate</i>, September 27, 2010<br />
</div></blockquote><br />
Note that someone at Forbes must have spotted the potential error in the last 8 words. While the original sentence remains on the Yahoo website, the sentence now ends “may not adequately represent how everyone in the area lives” at the Forbes website[http://www.forbes.com/2010/09/27/most-expensive-zip-codes-2010-lifestyle-real-estate-zip-codes-10-intro.html].<br><br />
<br />
Submitted by Margaret Cibes at the suggestion of Cris Wellington<br />
<br />
----<br />
<blockquote><br />
"The relationship between an area's income and mortality is so striking," the report says, "that on average, every $10,000 increase in an area's median income appears to buy its residents another year of life."<br />
<br><br />
<div align="right"> <br />
[http://www.startribune.com/lifestyle/health/104540289.html?elr=KArksLckD8EQDUoaEyqyP4O:DW3ckUiD3aPc:_Yyc:aUUs Key to long life? It may be in ... your ZIP code]<br>Minneapolis Star Tribune, 7 October 2010 </div><br />
</blockquote><br />
<br />
Submitted by Paul Alper<br />
<br />
==More fuel to feed the fiery controversy over mammograms==<br />
<br />
[http://www.nytimes.com/2010/09/30/health/research/30mammogram.html Mammogram Benefit Seen for Women in Their 40s], Gina Kolata, The New York Times, September 29, 2010.<br />
<br />
One of the most contentious debates in medicine is whether mammograms are beneficial to women between 40 and 50 years old. Earlier commentaries about this controversy appear in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_8#Mammograms_Validated_as_Key_in_Cancer_Fight Chance News 8], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_12#Screening Chance News 12], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_14#Gerd_Gigerenzer.27s_Calculated_Risks_Revisited Chance News 14], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_47#Bayes_theorem_in_the_news Chance News 47], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_58#Mammogram_Math Chance News 58], and [http://www.causeweb.org/wiki/chance/index.php/Chance_News_59#Ill_health_news Chance News 59].<br />
<br />
The first sentence in the latest article about mammography makes a bold claim...<br />
<br />
<blockquote>Researchers reported Wednesday that mammograms can cut the breast cancer death rate by 26 percent for women in their 40s.</blockquote><br />
<br />
...and the second sentence contradicts this claim.<br />
<br />
<blockquote>But their results were greeted with skepticism by some experts who say they may have overestimated the benefit.</blockquote><br />
<br />
The data set on which these bold claims were based is quite good.<br />
<br />
<blockquote>The new study took advantage of circumstances in Sweden, where since 1986 some counties have offered mammograms to women in their 40s and others have not, according to the lead author, Hakan Jonsson, professor of cancer epidemiology at Umea University in Sweden. The researchers compared breast cancer deaths in women who had a breast cancer diagnosis in counties that had screening with deaths in counties that did not. The rate was 26 percent lower in counties with screening.</blockquote><br />
<br />
Why the skepticism?<br />
<br />
<blockquote>One problem, said Dr. Peter C. Gotzsche of the Nordic Cochrane Center in Copenhagen, a nonprofit group that reviews health care research, is that the investigators counted the number of women who received a diagnosis of breast cancer and also died of it. They did not compare the broader breast cancer death rates in the counties.</blockquote><br />
<br />
A prominent statistician, Donald Berry, is also quoted in this article.<br />
<br />
===Questions===<br />
<br />
1. The research design in the current study was not randomized. Is this an issue?<br />
<br />
2. What are the barriers to conducting a randomized trial for mammography?<br />
<br />
==Even more fuel!==<br />
[http://www.healthnewsreview.org/blog/2010/10/this-is-the-way-the-swedish-mammography-study-couldshould-have-been-analyzed.html This is the way the Swedish mammography study could/should have been analyzed]<br><br />
by Gary Schwitzer, HealthNewsReview Blog, 4 October 2010<br />
<br />
Schwitzer's blog (which we first mentioned in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_59#Ill_health_news Chance News 59]) discusses news reports on public health issues, rating the stories according to a set [http://www.healthnewsreview.org/review-criteria.php rubric]. <br />
<br />
His present post concerns the Swedish mammogram study. He reviews the New York Times article described above, as well as reports from the <br />
[http://articles.latimes.com/2010/sep/29/news/la-heb-mammography-20100929 Los Angeles Times], the <br />
[http://www.npr.org/templates/story/story.php?storyId=130053888 Associated Press] and <br />
[http://news.health.com/2010/09/29/mammograms-save-lives-for-women-in-their-40s-study-says/ Health Day]. The last is singled out as the only one of the four that fails to make any mention of methodological concerns. However, Schwitzer goes on to argue that none of the articles does an adequate job explaining the methodological issues or their implications for the conclusions of the study. Read the full post for an interesting extended discussion on this.<br />
<br />
'''Question'''<br><br />
<br />
The discussion in the post notwithstanding, the individual HealthNewsReview ratings cited there give the [http://www.healthnewsreview.org/review.html?review_id=3203 NYT], <br />
the [http://www.healthnewsreview.org/review.html?review_id=3204 LA Times] <br />
and [http://www.healthnewsreview.org/review.html?review_id=3205 AP] <br />
stories 4 stars, 5 stars, and 5 stars (out of 5) respectively. What do you make of this?<br />
<br />
Submitted by Bill Peterson<br />
<br />
==Proofiness==<br />
<br />
Charles Seife is a marvelous writer of serious, interesting topics for the lay reader:<br />
<ul><br />
<li>''Zero: The Biography of a Dangerous Idea'', 2000<br />
<li>''Alpha & Omega: The Search for the Beginning and End of the Universe'', 2004<br />
<li>''Decoding The Universe'', 2007<br />
<li>''Sun in a Bottle: The Strange History of Fusion and the Science of Wishful Thinking'', 2008<br />
</ul><br />
His latest book, ''Proofiness: The Dark Arts of Mathematical Deception'', 2010, makes for especially good reading for students and teachers of statistics. The following web sites all comment on the book: The New York Times has a [http://www.nytimes.com/2010/09/19/books/review/Strogatz-t.html?_r=1&ref=bookreviews review] and an [http://www.nytimes.com/2010/09/16/books/excerpt-proofiness.html?ref=review excerpt]; NPR ran a story, [http://www.npr.org/templates/story/story.php?storyId=129972868 Lies, Damned Lies, And 'Proofiness']; additional reviews appeared<br />
in [http://www.nyjournalofbooks.com/2010/09/proofiness-dark-arts-of-mathematical.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+NewYorkJournalOfBooks+(NEW+YORK+JOURNAL+OF+BOOKS) New York Journal of Books] and [http://www.politicsdaily.com/2010/08/01/proofiness-using-numbers-to-fool-people-and-shape-political-deb/ Politics Daily].<br />
<br />
The reviews are entirely favorable, but don’t quite do justice to his presentation, so readers of Chance News are encouraged to read the book as well as the above commentaries.<br />
<br />
Seife defines proofiness as “the art of using bogus mathematical arguments to prove something that you know in your heart is true — even when it’s not.” However, he never makes the connection to [http://www.innumeracy.com/ Innumeracy] <br />
<blockquote><br />
A term meant to convey a person's inability to make sense of the numbers that run their lives. Innumeracy was coined by cognitive scientist Douglas R Hofstadter in one of his Metamagical Thema columns for Scientific American in the early nineteen eighties. Later that decade mathematician John Allen Paulos published the book Innumeracy. In it he includes the notion of chance as well to that of numbers.<br />
</blockquote><br />
Seife also does not refer to Stephen Colbert’s even more famous neologism, [http://en.wikipedia.org/wiki/Truthiness truthiness] which<br />
<br />
<blockquote><br />
is a "truth" that a person claims to know intuitively "from the gut" without regard to evidence, logic, intellectual examination, or facts.<br />
</blockquote><br />
<br />
Colbert himself put truthiness this way:<br />
"We're not talking about truth, we're talking about something that seems like truth – the truth we want to exist."<br />
<br />
Seife begins his Introduction with the famous quotation of Senator Joseph McCarthy on February 9, 1950:<br />
<br />
<blockquote><br />
"I have here in my hand a list of 205--a list of names that were made known to the Secretary of State as being members of the Communist party and who nevertheless are still working and shaping policy in the State Department."<br />
<blockquote><br />
</blockquote><br />
The 205 later became 57 and then 81. “It really didn’t matter whether the list had 205 or 57 or 81 names. The very fact that McCarthy had attached a number to his accusations imbued them with an aura of truth.” This “outrageous falsehood was given the appearance of absolute fact.”<br />
</blockquote><br />
<br />
Seife attempts to categorize the types of proofiness:<br />
<br />
A. Potemkin numbers--numerical facades that look like real numbers such as crowd estimates or the number of communists in the State Department.<br><br />
B. Disestimation, another neologism--“the act of taking a number too literally, understating or ignoring the uncertainties that surround it.”<br><br />
C. Fruit packing--“it’s not the individual numbers that are false; it is the presentation of the data that creates the proofiness.”<br><br />
D. Cherry picking--a form of fruit packing in which there is a “careful selection of data, choosing those that support the argument you wish to make while underplaying or ignoring data that undermine it.”<br><br />
E. Apples to oranges comparison--another form of fruit packing, for example, comparing dollar amounts without taking into account inflation.<br><br />
F. Apple polishing--another form of fruit packing, for example, deceptive graphs where the origin is missing; or, algebraically, misuse of mean and median.<br><br />
G. Causuistry, another neologism and a pun on the word casuistry--“a specialized form of casuistry where the fault in the argument comes from implying that there is a causal relationship between two things when in fact there isn’t any such linkage.”<br><br />
H. Randumbness, another neologism--“insisting that there is order where there is only chaos” or, “creating a pattern where there is none to see.”<br><br />
I. Regression to the moon--for example, extrapolating instead of interpolating regression results.<br><br />
<br />
None of these categories are new to teachers of statistics but his examples of the above forms of proofiness are detailed and when not frightening, are amusing; these examples include: the O.J. Simpson trial; the Franken-Coleman Minnesota Senate election and Bush vs. Gore in 2000 (he terms them “electile dysfunctions”); nuclear testing; risk analysis; the space program; the Vietnam war; and, determination of the perfect butt (page 66 contains the formula for callipygianness--a word which is '''not''' a neologism). He is particularly incisive when he discusses systematic error when it overwhelms and confuses the notion of error due to sampling, and thus, invalidating the so-called margin of error in polling. <br />
<br />
===Discussion===<br />
<br />
1. If it is so obvious today that McCarthy was fabricating the numbers -- in the parlance of today, he was fact-free -- why was he so successful so long in the 1950s? And why did his allegations and point of view live on well after his death in 1957?<br />
<br />
2. Seife devotes a great deal of time to convince the reader that the U.S. census would be more accurate if it did not attempt to count everyone but rather did statistical sampling and avoid many of the systematic errors. Why would this be true? Why did the U.S. Supreme Court deem otherwise?<br />
<br />
3. Some of his strongest criticism is directed at journalists and polling organizations. The chapter entitled, “Poll Cats.” On page 120 he says, “Internet polls have no basis in reality whatsoever.” Why? “Yet, CNN.com has an Internet poll on its front page every day.” Again, why? Non Internet polls do not come off much better due to flagrant non-statistical faults.<br />
<br />
4. With regard to the O.J. Simpson murder trial, Seife paraphrases one of Simpson's defense attorney's claim that “only one in a thousand wife-beaters winds up murdering his spouse. One in a thousand! Such a small probability means that O.J. Simpson almost certainly isn’t the murderer, right? “ Use Bayes theorem along with reasonable numbers about the number of wives being murdered to indicate that Simpson’s probability of being the culprit is much higher.<br />
<br />
5. Regression to the moon also refers to totally nonsensical use of regression. A more detailed look (page 66) at callipygianness reveals<br />
<center><br />
Callipygianness = (S + C) x (B + F) / (T - V) ,<br />
</center><br />
where S is shape, C is circularity, B is bounciness, F is firmness, T is texture, and V is waist-to-hip ratio. Seife found this regression result, not surprisingly, on <br />
[http://www.foxnews.com/story/0,2933,191622,00.html Fox News] and the reporter was from another Murdoch enterprise, The New York Post. Why does Seife find this regression result so ridiculous? On the same page, there is a regression result for “Misery” which depends upon weather, debt, motivation, “the need to take action,” and some other variables. “[I]t proved --scientifically--that the most miserable day of the year [2005] was January 24.” The regression result for “Happiness” appears on the preceding page. Why does Seife claim that these three are examples of Potemkin numbers?<br />
<br />
6. To return to McCarthy’s proofiness, his original speech about the 205 communists in the State Department was made in Wheeling, West Virginia to the Republican Women’s Club and made no waves whatsoever for days. Seife does not mention this, but only after the New York Times and the Washington Post publicized the speech did it ignite his fame. Contrast that time lag with today’s instant communication.<br />
<br />
7. Seife on page 226 repeats a famous adage of the journalism world: “If your mother says she loves you, check it out.” He then looks at the Pentagon’s weekly body counts and monthly hamlet evaluations during the Vietnam War. By page 228 he describes an auto-industry market research report which shows that driving a Hummer H3 is “better for the environment than driving the energy-efficient Toyota Prius hybrid.” Why did he juxtapose these two examples?<br />
<br />
8. The last paragraph of the book is: “Mathematical sophistication is the only antidote to proofiness and our degree of knowledge will determine whether we succumb to proofiness or fight against it. It’s more than mere rhetoric; our democracy may well rise or fall by the numbers.” Why might his “antidote” be insufficient?<br />
<br />
Submitted by Paul Alper<br />
<br />
==Sampling saliva==<br />
[http://www.thenation.com/article/154596/freshmen-specimen “Freshmen Specimen”]<br><br />
by Patricia J. Williams, <i>The Nation</i>, September 27, 2010<br> <br />
<br />
In this column, law professor Williams describes reactions to the University of California’s Berkeley project [http://onthesamepage.berkeley.edu/ “Bring Your Genes to Cal”], in which 5500 incoming freshmen were asked to provide saliva samples for the purpose of “bring[ing] the student body together in the same manner that reading To Kill a Mockingbird might have in the past.” More than 700 students submitted their samples to an uncertified Berkeley lab, and the samples were analyzed for “susceptibility to alcoholism, lactose intolerance and relative metabolism of folic acid.”<br><br />
<br />
<blockquote>[T]he California Department of Public Health barred the university from dispensing individual profiles on the grounds that genetic analysis is correlative only and is neither necessarily predictive nor diagnostic at this point. A collective comparison of the class's genetic data was permitted, however, and circulated in "anonymized" form at orientation.</blockquote><br />
<br />
Some ethical issues that have been raised include:<br><br />
(a) privacy, despite the “anonymizing” of results;<br><br />
(b) ownership of the data with respect to commercialization, patentability, remuneration, <i>etc.</i>;<br><br />
(c) promotion of the concept that a genetic correlation is a “100 percent infallible guarantee” of anything;<br><br />
(d) motive with respect to promoting sales of swab kits.<br><br />
<br />
The article refers to a Stanford University medical school class “spit party” and to a University of Minnesota [http://www.peds.umn.edu/gopherkids/ "Gopher Kids"] program (free gifts for saliva swabs at a state fair).<br />
<br />
Readers might be interested in a paper from ETC Group, a Canadian-based international organization, [http://www.etcgroup.org/upload/publication/675/02/genomixspitkits_03march08.pdf "Direct-to-Consumer DNA Testing and the Myth of Personalized Medicine: Spit Kits, SNP Chips and Human Genomics"]. Or they might want to google "spit party" to see how widespread these activities are.<br />
<br />
===Discussion===<br />
<br />
1. Explain what the Public Health Department meant by the clause "genetic analysis is correlative only." <br />
<br />
2. Comment on the following statement in the article: “The university advertises participation as altruistic, a contribution to public health and human knowledge.”<br><br />
<br />
3. The author of the article refers to the process of collecting saliva samples as a “commodity exchange.” Do you agree with the author?<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Correlation as investment tool==<br />
[http://online.wsj.com/article/SB10001424052748704129204575505550134652416.html?KEYWORDS=jonnelle+marte “Why the Math of Correlation Matters”]<br><br />
by Jonnelle Marte, <i>The Wall Street Journal</i>, October 4, 2010<br><br />
<br />
This article discusses how a mutual-fund investor might employ the concept of correlation in aiming to diversify, and/or reduce volatility in, an investment portfolio. <br />
<br />
<blockquote>“If your investments move in lock step, or are highly correlated, "you'll either be all right or all wrong," says [an equity market strategist].</blockquote><br />
<br />
It describes how correlation is measured in comparing two investments: <br />
<blockquote>A correlation close to zero means the performance of one asset has little or no connection to that of the other. A correlation of 1 is a perfect positive correlation, meaning the two assets always move in sync—in the same direction, and at a scale that doesn't vary. For instance, Asset A will always move at twice the magnitude of Asset B. A correlation of minus 1 is a perfect negative correlation. The assets move in opposite directions at a scale that doesn't vary.</blockquote><br />
<br />
And it points out that daily, weekly, or monthly returns can be compared, and provides a table of correlations of various assets to the S&P 500 over a 10-year period. At the extremes are a +0.89 correlation between international stocks and the S&P, versus a -0.39 correlation between intermediate U.S. bonds and the S&P.<br> <br />
<br />
There are two caveats. The term of the analysis is a key consideration; for example, the 10-year correlation of -0.39 referred to above became a +0.08 correlation for an over-80-year period. Also, a crisis, such as the 2008 “crash,” may result in a “surge” in correlations, when investments of all kinds decreased.<br><br />
<br />
The author states that investors may choose assets that are uncorrelated, or negatively correlated, to the S&P 500, in order to balance, or minimize, risk.<br />
<blockquote>Such strategies are only recommended in the short term because they essentially cancel out returns. Holding too many negatively correlated assets can be a little like trying to hit the gas while slamming on the brakes, says [one financial analyst].</blockquote><br />
<br />
Interested readers are directed to the website [http://assetcorrelation.com "Asset Correlations"], where they will find a table of correlations between pairs of asset categories, or they may create their own tables.<br><br />
<br />
Two bloggers commented[http://online.wsj.com/article/SB10001424052748704129204575505550134652416.html?KEYWORDS=jonnelle+marte#articleTabs%3Dcomments]:<br><br />
<br />
(a) "This is NOT the way correlation works!!<br><br />
"A correlation of negative one does NOT mean that when asset class A returns 5%, asset class B returns negative 5%. It means that when asset class A returns greater than its expected return (say expected return of 5% and A is returning 7%), then asset class B will be return less than its expected return (if asset class B also has an expected return of 5%, then it would be returning 3%)."<br><br />
<br />
(b) "Good point. To summarize, correlation indicates if variables tend to move in the same direction, but gives no indication about the amplitude of these movements."<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Money isn’t everything, at least in baseball==<br />
[http://online.wsj.com/article/SB10001424052748703743504575493942146685242.html?KEYWORDS=matthew+futterman “The Year Money Didn’t Matter”]<br><br />
By Matthew Futterman, <i>The Wall Street Journal</i>, September 16, 2010<br><br />
<br />
This article reports that the correlation between Major League Baseball player payrolls and games won will be at its lowest level (0.14) since the 1994 players’ strike, if “current standings hold up through the end of the season.” And it contains a graph of correlations for the period 1995-2010 to date.<br><br />
<br />
http://sg.wsj.net/public/resources/images/WK-AV449_BASEBA_NS_20100916175614.gif<br />
<br />
While all eight teams reaching the playoffs had among the 10 top payrolls in 1999, only three of the highest payroll teams – but four of the lowest – will probably make the 2010 playoffs, if standings hold up through the end of this season.<br><br />
<br />
Despite the fact that top and bottom payrolls have grown farther apart in dollars, one factor in the current situation may be the 2002 revenue-sharing agreement, by which wealthier ball clubs now share increasing amounts of revenue with poorer clubs. Some of the revenue-receiving poorer teams have invested in non-payroll expenses such as scouting, trades, <i>etc</i>., with resulting improvements in performance, while some of the revenue-contributing teams’ performances have been constrained by long-term contracts with under-performing players, as well as by player injuries this year.<br><br />
See more data:<br><br />
(a) <i>Forbes</i> blog on 2010 baseball costs per win in [http://blogs.forbes.com/sportsmoney/2010/10/04/baseballs-most-and-least-efficient-teams-for-the-2010-season/ “Baseball’s Most and Least Efficient Teams for the 2010 Season”]<br><br />
(b) <i>New York Times</i> chart of payrolls vs. win-loss records over the period 2001-2010 in [http://www.nytimes.com/interactive/2010/09/26/sports/20090926-score-graphic.html “Putting a Price Tag on Winning”]<br><br />
(c) ESPN chart and table of payrolls vs. win-loss records over the period 1998-2008 in [http://sports.espn.go.com/espnmag/story?id=3816824 “The Biz: The Price of Winning”]<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Medical misinformation==<br />
[http://www.theatlantic.com/magazine/archive/2010/11/lies-damned-lies-and-medical-science/8269/ Lies, damned lies, and medical science]<br><br />
by David H. Freedman, ''The Atlantic'', November 2010<br />
<br />
To be continued...<br />
<br />
==World Statistics Day==<br />
<br />
See the U.S. Census Bureau website[http://www.census.gov/newsroom/releases/archives/news_conferences/2010-10-20_worldstats.html] for videos and other information related to the first World Statistics Day: October 20, 2010.<br> <br />
<br />
Note that the date, written in day/month/year format, is 20/10/2010. It will be interesting to see how the day is chosen in year 2013 or subsequent years.<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Racial disparity in Wikimedia Commons photos==<br />
<br />
A short article was [http://www.examiner.com/wiki-edits-in-national/racist-undertones-on-wikipedia published October 20] on Examiner.com, drawing attention to a racial disparity found in two distinct sections of freely-licensed visual content published at Wikimedia Commons (a sister site of Wikipedia). While the subject matter of the photos may make some uncomfortable, the parent Wikimedia Foundation did in fact [http://www.examiner.com/wiki-edits-in-national/wikimedia-foundation-rules-on-naughty-bits hire a consultant] to evaluate the situation from an independent perspective. <br />
<br />
What is boils down to is that the consultant said he evaluated 1,000 images of male sex organs that are found on Wikimedia Commons, and (by his count) not a single one was of a non-white male. In another (much smaller) category of photos and illustrations called "[http://commons.wikimedia.org/wiki/Category:Topless_adolescent_girls topless adolescent girls]", some 25 of the 26 images portray non-white subjects. <br />
<br />
As the Examiner article asks, is this a tacit form of racism? The odds that these two categories ''coincidentally'' ending up 99.9% white and 96.2% non-white, respectively, seem too hard to imagine.<br />
<br />
===Discussion===<br />
<br />
* What other factors might explain why a racial disparity is found in these categories?<br />
* Do you see any problematic factors in how a collection of encyclopedic images are gathered, when there is no editorial board guiding acquisition?<br />
<br />
Submitted by Gregory Kohs</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_67&diff=11331Chance News 672010-10-22T15:43:30Z<p>Thekohser: Discussion (sub-heading)</p>
<hr />
<div>==Quotations==<br />
==Forsooth==<br />
An article describes two brands of athletic wear that are claimed to optimize performance via embedded holograms (Power Balance) and water-soluble titanium (Phiten).<br />
<blockquote>“A lot of these products are a sort of merchandized superstition. …. [A French surfer states,] ‘But if wearing the thing makes you think you feel or perform better, who cares?’”<br><br />
<div align="right"><br />
[http://www.time.com/time/magazine/article/0,9171,2021057,00.html “Wrist Watch”], <i>TIME</i>, October 4, 2010<br />
</div><br />
</blockquote><br />
Submitted by Margaret Cibes<br />
<br />
-----<br />
<blockquote>"A scant 1,391 people live in 91008 ZIP code, and only 12 homes are currently on the market. So a single high-priced listing (like the mammoth nine-bedroom, built this year, that's selling for $19.8 million) is enough to skew the median price skyward."<br><br />
<div align="right">[http://realestate.yahoo.com/promo/americas-most-expensive-zip-codes-2010.html America’s Most Expensive ZIP Codes 2010], <br><i>Yahoo! Real Estate</i>, September 27, 2010<br />
</div></blockquote><br />
Note that someone at Forbes must have spotted the potential error in the last 8 words. While the original sentence remains on the Yahoo website, the sentence now ends “may not adequately represent how everyone in the area lives” at the Forbes website[http://www.forbes.com/2010/09/27/most-expensive-zip-codes-2010-lifestyle-real-estate-zip-codes-10-intro.html].<br><br />
<br />
Submitted by Margaret Cibes at the suggestion of Cris Wellington<br />
<br />
----<br />
<blockquote><br />
"The relationship between an area's income and mortality is so striking," the report says, "that on average, every $10,000 increase in an area's median income appears to buy its residents another year of life."<br />
<br><br />
<div align="right"> <br />
[http://www.startribune.com/lifestyle/health/104540289.html?elr=KArksLckD8EQDUoaEyqyP4O:DW3ckUiD3aPc:_Yyc:aUUs Key to long life? It may be in ... your ZIP code]<br>Minneapolis Star Tribune, 7 October 2010 </div><br />
</blockquote><br />
<br />
Submitted by Paul Alper<br />
<br />
==More fuel to feed the fiery controversy over mammograms==<br />
<br />
[http://www.nytimes.com/2010/09/30/health/research/30mammogram.html Mammogram Benefit Seen for Women in Their 40s], Gina Kolata, The New York Times, September 29, 2010.<br />
<br />
One of the most contentious debates in medicine is whether mammograms are beneficial to women between 40 and 50 years old. Earlier commentaries about this controversy appear in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_8#Mammograms_Validated_as_Key_in_Cancer_Fight Chance News 8], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_12#Screening Chance News 12], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_14#Gerd_Gigerenzer.27s_Calculated_Risks_Revisited Chance News 14], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_47#Bayes_theorem_in_the_news Chance News 47], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_58#Mammogram_Math Chance News 58], and [http://www.causeweb.org/wiki/chance/index.php/Chance_News_59#Ill_health_news Chance News 59].<br />
<br />
The first sentence in the latest article about mammography makes a bold claim...<br />
<br />
<blockquote>Researchers reported Wednesday that mammograms can cut the breast cancer death rate by 26 percent for women in their 40s.</blockquote><br />
<br />
...and the second sentence contradicts this claim.<br />
<br />
<blockquote>But their results were greeted with skepticism by some experts who say they may have overestimated the benefit.</blockquote><br />
<br />
The data set on which these bold claims were based is quite good.<br />
<br />
<blockquote>The new study took advantage of circumstances in Sweden, where since 1986 some counties have offered mammograms to women in their 40s and others have not, according to the lead author, Hakan Jonsson, professor of cancer epidemiology at Umea University in Sweden. The researchers compared breast cancer deaths in women who had a breast cancer diagnosis in counties that had screening with deaths in counties that did not. The rate was 26 percent lower in counties with screening.</blockquote><br />
<br />
Why the skepticism?<br />
<br />
<blockquote>One problem, said Dr. Peter C. Gotzsche of the Nordic Cochrane Center in Copenhagen, a nonprofit group that reviews health care research, is that the investigators counted the number of women who received a diagnosis of breast cancer and also died of it. They did not compare the broader breast cancer death rates in the counties.</blockquote><br />
<br />
A prominent statistician, Donald Berry, is also quoted in this article.<br />
<br />
===Questions===<br />
<br />
1. The research design in the current study was not randomized. Is this an issue?<br />
<br />
2. What are the barriers to conducting a randomized trial for mammography?<br />
<br />
==Even more fuel!==<br />
[http://www.healthnewsreview.org/blog/2010/10/this-is-the-way-the-swedish-mammography-study-couldshould-have-been-analyzed.html This is the way the Swedish mammography study could/should have been analyzed]<br><br />
by Gary Schwitzer, HealthNewsReview Blog, 4 October 2010<br />
<br />
Schwitzer's blog (which we first mentioned in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_59#Ill_health_news Chance News 59]) discusses news reports on public health issues, rating the stories according to a set [http://www.healthnewsreview.org/review-criteria.php rubric]. <br />
<br />
His present post concerns the Swedish mammogram study. He reviews the New York Times article described above, as well as reports from the <br />
[http://articles.latimes.com/2010/sep/29/news/la-heb-mammography-20100929 Los Angeles Times], the <br />
[http://www.npr.org/templates/story/story.php?storyId=130053888 Associated Press] and <br />
[http://news.health.com/2010/09/29/mammograms-save-lives-for-women-in-their-40s-study-says/ Health Day]. The last is singled out as the only one of the four that fails to make any mention of methodological concerns. However, Schwitzer goes on to argue that none of the articles does an adequate job explaining the methodological issues or their implications for the conclusions of the study. Read the full post for an interesting extended discussion on this.<br />
<br />
'''Question'''<br><br />
<br />
The discussion in the post notwithstanding, the individual HealthNewsReview ratings cited there give the [http://www.healthnewsreview.org/review.html?review_id=3203 NYT], <br />
the [http://www.healthnewsreview.org/review.html?review_id=3204 LA Times] <br />
and [http://www.healthnewsreview.org/review.html?review_id=3205 AP] <br />
stories 4 stars, 5 stars, and 5 stars (out of 5) respectively. What do you make of this?<br />
<br />
Submitted by Bill Peterson<br />
<br />
==Proofiness==<br />
<br />
Charles Seife is a marvelous writer of serious, interesting topics for the lay reader:<br />
<ul><br />
<li>''Zero: The Biography of a Dangerous Idea'', 2000<br />
<li>''Alpha & Omega: The Search for the Beginning and End of the Universe'', 2004<br />
<li>''Decoding The Universe'', 2007<br />
<li>''Sun in a Bottle: The Strange History of Fusion and the Science of Wishful Thinking'', 2008<br />
</ul><br />
His latest book, ''Proofiness: The Dark Arts of Mathematical Deception'', 2010, makes for especially good reading for students and teachers of statistics. The following web sites all comment on the book: The New York Times has a [http://www.nytimes.com/2010/09/19/books/review/Strogatz-t.html?_r=1&ref=bookreviews review] and an [http://www.nytimes.com/2010/09/16/books/excerpt-proofiness.html?ref=review excerpt]; NPR ran a story, [http://www.npr.org/templates/story/story.php?storyId=129972868 Lies, Damned Lies, And 'Proofiness']; additional reviews appeared<br />
in [http://www.nyjournalofbooks.com/2010/09/proofiness-dark-arts-of-mathematical.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+NewYorkJournalOfBooks+(NEW+YORK+JOURNAL+OF+BOOKS) New York Journal of Books] and [http://www.politicsdaily.com/2010/08/01/proofiness-using-numbers-to-fool-people-and-shape-political-deb/ Politics Daily].<br />
<br />
The reviews are entirely favorable, but don’t quite do justice to his presentation, so readers of Chance News are encouraged to read the book as well as the above commentaries.<br />
<br />
Seife defines proofiness as “the art of using bogus mathematical arguments to prove something that you know in your heart is true — even when it’s not.” However, he never makes the connection to [http://www.innumeracy.com/ Innumeracy] <br />
<blockquote><br />
A term meant to convey a person's inability to make sense of the numbers that run their lives. Innumeracy was coined by cognitive scientist Douglas R Hofstadter in one of his Metamagical Thema columns for Scientific American in the early nineteen eighties. Later that decade mathematician John Allen Paulos published the book Innumeracy. In it he includes the notion of chance as well to that of numbers.<br />
</blockquote><br />
Seife also does not refer to Stephen Colbert’s even more famous neologism, [http://en.wikipedia.org/wiki/Truthiness truthiness] which<br />
<br />
<blockquote><br />
is a "truth" that a person claims to know intuitively "from the gut" without regard to evidence, logic, intellectual examination, or facts.<br />
</blockquote><br />
<br />
Colbert himself put truthiness this way:<br />
"We're not talking about truth, we're talking about something that seems like truth – the truth we want to exist."<br />
<br />
Seife begins his Introduction with the famous quotation of Senator Joseph McCarthy on February 9, 1950:<br />
<br />
<blockquote><br />
"I have here in my hand a list of 205--a list of names that were made known to the Secretary of State as being members of the Communist party and who nevertheless are still working and shaping policy in the State Department."<br />
<blockquote><br />
</blockquote><br />
The 205 later became 57 and then 81. “It really didn’t matter whether the list had 205 or 57 or 81 names. The very fact that McCarthy had attached a number to his accusations imbued them with an aura of truth.” This “outrageous falsehood was given the appearance of absolute fact.”<br />
</blockquote><br />
<br />
Seife attempts to categorize the types of proofiness:<br />
<br />
A. Potemkin numbers--numerical facades that look like real numbers such as crowd estimates or the number of communists in the State Department.<br><br />
B. Disestimation, another neologism--“the act of taking a number too literally, understating or ignoring the uncertainties that surround it.”<br><br />
C. Fruit packing--“it’s not the individual numbers that are false; it is the presentation of the data that creates the proofiness.”<br><br />
D. Cherry picking--a form of fruit packing in which there is a “careful selection of data, choosing those that support the argument you wish to make while underplaying or ignoring data that undermine it.”<br><br />
E. Apples to oranges comparison--another form of fruit packing, for example, comparing dollar amounts without taking into account inflation.<br><br />
F. Apple polishing--another form of fruit packing, for example, deceptive graphs where the origin is missing; or, algebraically, misuse of mean and median.<br><br />
G. Causuistry, another neologism and a pun on the word casuistry--“a specialized form of casuistry where the fault in the argument comes from implying that there is a causal relationship between two things when in fact there isn’t any such linkage.”<br><br />
H. Randumbness, another neologism--“insisting that there is order where there is only chaos” or, “creating a pattern where there is none to see.”<br><br />
I. Regression to the moon--for example, extrapolating instead of interpolating regression results.<br><br />
<br />
None of these categories are new to teachers of statistics but his examples of the above forms of proofiness are detailed and when not frightening, are amusing; these examples include: the O.J. Simpson trial; the Franken-Coleman Minnesota Senate election and Bush vs. Gore in 2000 (he terms them “electile dysfunctions”); nuclear testing; risk analysis; the space program; the Vietnam war; and, determination of the perfect butt (page 66 contains the formula for callipygianness--a word which is '''not''' a neologism). He is particularly incisive when he discusses systematic error when it overwhelms and confuses the notion of error due to sampling, and thus, invalidating the so-called margin of error in polling. <br />
<br />
===Discussion===<br />
<br />
1. If it is so obvious today that McCarthy was fabricating the numbers--in the parlance of today, he was fact-free--why was he so successful so long in the 1950s? And why did his allegations and point of view live on well after his death in 1957?<br />
<br />
2. Seife devotes a great deal of time to convince the reader that the U.S. census would be more accurate if it did not attempt to count everyone but rather did statistical sampling and avoid many of the systematic errors. Why would this be true? Why did the U.S. Supreme Court deem otherwise?<br />
<br />
3. Some of his strongest criticism is directed at journalists and polling organizations. The chapter entitled, “Poll Cats.” On page 120 he says, “Internet polls have no basis in reality whatsoever.” Why? “Yet, CNN.com has an Internet poll on its front page every day.” Again, why? Non Internet polls do not come off much better due to flagrant non-statistical faults.<br />
<br />
4. With regard to the O.J. Simpson murder trial, Seife paraphrases one of Simpson's defense attorney's claim that “only one in a thousand wife-beaters winds up murdering his spouse. One in a thousand! Such a small probability means that O.J. Simpson almost certainly isn’t the murderer, right? “ Use Bayes theorem along with reasonable numbers about the number of wives being murdered to indicate that Simpson’s probability of being the culprit is much higher.<br />
<br />
5. Regression to the moon also refers to totally nonsensical use of regression. A more detailed look (page 66) at callipygianness reveals<br />
<center><br />
Callipygianness = (S + C) x (B + F) / (T - V) ,<br />
</center><br />
where S is shape, C is circularity, B is bounciness, F is firmness, T is texture, and V is waist-to-hip ratio. Seife found this regression result, not surprisingly, on <br />
[http://www.foxnews.com/story/0,2933,191622,00.html Fox News] and the reporter was from another Murdoch enterprise, The New York Post. Why does Seife find this regression result so ridiculous? On the same page, there is a regression result for “Misery” which depends upon weather, debt, motivation, “the need to take action,” and some other variables. “[I]t proved --scientifically--that the most miserable day of the year [2005] was January 24.” The regression result for “Happiness” appears on the preceding page. Why does Seife claim that these three are examples of Potemkin numbers?<br />
<br />
6. To return to McCarthy’s proofiness, his original speech about the 205 communists in the State Department was made in Wheeling, West Virginia to the Republican Women’s Club and made no waves whatsoever for days. Seife does not mention this, but only after the New York Times and the Washington Post publicized the speech did it ignite his fame. Contrast that time lag with today’s instant communication.<br />
<br />
7. Seife on page 226 repeats a famous adage of the journalism world: “If your mother says she loves you, check it out.” He then looks at the Pentagon’s weekly body counts and monthly hamlet evaluations during the Vietnam War. By page 228 he describes an auto-industry market research report which shows that driving a Hummer H3 is “better for the environment than driving the energy-efficient Toyota Prius hybrid.” Why did he juxtapose these two examples?<br />
<br />
8. The last paragraph of the book is: “Mathematical sophistication is the only antidote to proofiness and our degree of knowledge will determine whether we succumb to proofiness or fight against it. It’s more than mere rhetoric; our democracy may well rise or fall by the numbers.” Why might his “antidote” be insufficient?<br />
<br />
Submitted by Paul Alper<br />
<br />
==Sampling saliva==<br />
[http://www.thenation.com/article/154596/freshmen-specimen “Freshmen Specimen”]<br><br />
by Patricia J. Williams, <i>The Nation</i>, September 27, 2010<br> <br />
<br />
In this column, law professor Williams describes reactions to the University of California’s Berkeley project [http://onthesamepage.berkeley.edu/ “Bring Your Genes to Cal”], in which 5500 incoming freshmen were asked to provide saliva samples for the purpose of “bring[ing] the student body together in the same manner that reading To Kill a Mockingbird might have in the past.” More than 700 students submitted their samples to an uncertified Berkeley lab, and the samples were analyzed for “susceptibility to alcoholism, lactose intolerance and relative metabolism of folic acid.”<br><br />
<br />
<blockquote>[T]he California Department of Public Health barred the university from dispensing individual profiles on the grounds that genetic analysis is correlative only and is neither necessarily predictive nor diagnostic at this point. A collective comparison of the class's genetic data was permitted, however, and circulated in "anonymized" form at orientation.</blockquote><br />
<br />
Some ethical issues that have been raised include:<br><br />
(a) privacy, despite the “anonymizing” of results;<br><br />
(b) ownership of the data with respect to commercialization, patentability, remuneration, <i>etc.</i>;<br><br />
(c) promotion of the concept that a genetic correlation is a “100 percent infallible guarantee” of anything;<br><br />
(d) motive with respect to promoting sales of swab kits.<br><br />
<br />
The article refers to a Stanford University medical school class “spit party” and to a University of Minnesota [http://www.peds.umn.edu/gopherkids/ "Gopher Kids"] program (free gifts for saliva swabs at a state fair).<br />
<br />
Readers might be interested in a paper from ETC Group, a Canadian-based international organization, [http://www.etcgroup.org/upload/publication/675/02/genomixspitkits_03march08.pdf "Direct-to-Consumer DNA Testing and the Myth of Personalized Medicine: Spit Kits, SNP Chips and Human Genomics"]. Or they might want to google "spit party" to see how widespread these activities are.<br />
<br />
===Discussion===<br />
<br />
1. Explain what the Public Health Department meant by the clause "genetic analysis is correlative only." <br />
<br />
2. Comment on the following statement in the article: “The university advertises participation as altruistic, a contribution to public health and human knowledge.”<br><br />
<br />
3. The author of the article refers to the process of collecting saliva samples as a “commodity exchange.” Do you agree with the author?<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Correlation as investment tool==<br />
[http://online.wsj.com/article/SB10001424052748704129204575505550134652416.html?KEYWORDS=jonnelle+marte “Why the Math of Correlation Matters”]<br><br />
by Jonnelle Marte, <i>The Wall Street Journal</i>, October 4, 2010<br><br />
<br />
This article discusses how a mutual-fund investor might employ the concept of correlation in aiming to diversify, and/or reduce volatility in, an investment portfolio. <br />
<br />
<blockquote>“If your investments move in lock step, or are highly correlated, "you'll either be all right or all wrong," says [an equity market strategist].</blockquote><br />
<br />
It describes how correlation is measured in comparing two investments: <br />
<blockquote>A correlation close to zero means the performance of one asset has little or no connection to that of the other. A correlation of 1 is a perfect positive correlation, meaning the two assets always move in sync—in the same direction, and at a scale that doesn't vary. For instance, Asset A will always move at twice the magnitude of Asset B. A correlation of minus 1 is a perfect negative correlation. The assets move in opposite directions at a scale that doesn't vary.</blockquote><br />
<br />
And it points out that daily, weekly, or monthly returns can be compared, and provides a table of correlations of various assets to the S&P 500 over a 10-year period. At the extremes are a +0.89 correlation between international stocks and the S&P, versus a -0.39 correlation between intermediate U.S. bonds and the S&P.<br> <br />
<br />
There are two caveats. The term of the analysis is a key consideration; for example, the 10-year correlation of -0.39 referred to above became a +0.08 correlation for an over-80-year period. Also, a crisis, such as the 2008 “crash,” may result in a “surge” in correlations, when investments of all kinds decreased.<br><br />
<br />
The author states that investors may choose assets that are uncorrelated, or negatively correlated, to the S&P 500, in order to balance, or minimize, risk.<br />
<blockquote>Such strategies are only recommended in the short term because they essentially cancel out returns. Holding too many negatively correlated assets can be a little like trying to hit the gas while slamming on the brakes, says [one financial analyst].</blockquote><br />
<br />
Interested readers are directed to the website [http://assetcorrelation.com "Asset Correlations"], where they will find a table of correlations between pairs of asset categories, or they may create their own tables.<br><br />
<br />
Two bloggers commented[http://online.wsj.com/article/SB10001424052748704129204575505550134652416.html?KEYWORDS=jonnelle+marte#articleTabs%3Dcomments]:<br><br />
<br />
(a) "This is NOT the way correlation works!!<br><br />
"A correlation of negative one does NOT mean that when asset class A returns 5%, asset class B returns negative 5%. It means that when asset class A returns greater than its expected return (say expected return of 5% and A is returning 7%), then asset class B will be return less than its expected return (if asset class B also has an expected return of 5%, then it would be returning 3%)."<br><br />
<br />
(b) "Good point. To summarize, correlation indicates if variables tend to move in the same direction, but gives no indication about the amplitude of these movements."<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Money isn’t everything, at least in baseball==<br />
[http://online.wsj.com/article/SB10001424052748703743504575493942146685242.html?KEYWORDS=matthew+futterman “The Year Money Didn’t Matter”]<br><br />
By Matthew Futterman, <i>The Wall Street Journal</i>, September 16, 2010<br><br />
<br />
This article reports that the correlation between Major League Baseball player payrolls and games won will be at its lowest level (0.14) since the 1994 players’ strike, if “current standings hold up through the end of the season.” And it contains a graph of correlations for the period 1995-2010 to date.<br><br />
<br />
http://sg.wsj.net/public/resources/images/WK-AV449_BASEBA_NS_20100916175614.gif<br />
<br />
While all eight teams reaching the playoffs had among the 10 top payrolls in 1999, only three of the highest payroll teams – but four of the lowest – will probably make the 2010 playoffs, if standings hold up through the end of this season.<br><br />
<br />
Despite the fact that top and bottom payrolls have grown farther apart in dollars, one factor in the current situation may be the 2002 revenue-sharing agreement, by which wealthier ball clubs now share increasing amounts of revenue with poorer clubs. Some of the revenue-receiving poorer teams have invested in non-payroll expenses such as scouting, trades, <i>etc</i>., with resulting improvements in performance, while some of the revenue-contributing teams’ performances have been constrained by long-term contracts with under-performing players, as well as by player injuries this year.<br><br />
See more data:<br><br />
(a) <i>Forbes</i> blog on 2010 baseball costs per win in [http://blogs.forbes.com/sportsmoney/2010/10/04/baseballs-most-and-least-efficient-teams-for-the-2010-season/ “Baseball’s Most and Least Efficient Teams for the 2010 Season”]<br><br />
(b) <i>New York Times</i> chart of payrolls vs. win-loss records over the period 2001-2010 in [http://www.nytimes.com/interactive/2010/09/26/sports/20090926-score-graphic.html “Putting a Price Tag on Winning”]<br><br />
(c) ESPN chart and table of payrolls vs. win-loss records over the period 1998-2008 in [http://sports.espn.go.com/espnmag/story?id=3816824 “The Biz: The Price of Winning”]<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Medical misinformation==<br />
[http://www.theatlantic.com/magazine/archive/2010/11/lies-damned-lies-and-medical-science/8269/ Lies, damned lies, and medical science]<br><br />
by David H. Freedman, ''The Atlantic'', November 2010<br />
<br />
To be continued...<br />
<br />
==World Statistics Day==<br />
<br />
See the U.S. Census Bureau website[http://www.census.gov/newsroom/releases/archives/news_conferences/2010-10-20_worldstats.html] for videos and other information related to the first World Statistics Day: October 20, 2010.<br> <br />
<br />
Note that the date, written in day/month/year format, is 20/10/2010. It will be interesting to see how the day is chosen in year 2013 or subsequent years.<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Racial disparity in Wikimedia Commons photos==<br />
<br />
A short article was [http://www.examiner.com/wiki-edits-in-national/racist-undertones-on-wikipedia published October 20] on Examiner.com, drawing attention to a racial disparity found in two distinct sections of freely-licensed visual content published at Wikimedia Commons (a sister site of Wikipedia). While the subject matter of the photos may make some uncomfortable, the parent Wikimedia Foundation did in fact [http://www.examiner.com/wiki-edits-in-national/wikimedia-foundation-rules-on-naughty-bits hire a consultant] to evaluate the situation from an independent perspective. <br />
<br />
What is boils down to is that the consultant said he evaluated 1,000 images of male sex organs that are found on Wikimedia Commons, and (by his count) not a single one was of a non-white male. In another (much smaller) category of photos and illustrations called "[http://commons.wikimedia.org/wiki/Category:Topless_adolescent_girls topless adolescent girls]", some 25 of the 26 images portray non-white subjects. <br />
<br />
As the Examiner article asks, is this a tacit form of racism? The odds that these two categories ''coincidentally'' ending up 99.9% white and 96.2% non-white, respectively, seem too hard to imagine.<br />
<br />
===Discussion===<br />
<br />
* What other factors might explain why a racial disparity is found in these categories?<br />
* Do you see any problematic factors in how a collection of encyclopedic images are gathered, when there is no editorial board guiding acquisition?<br />
<br />
Submitted by Gregory Kohs</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_67&diff=11330Chance News 672010-10-22T15:41:29Z<p>Thekohser: /* Racial disparity in Wikimedia Commons photos */</p>
<hr />
<div>==Quotations==<br />
==Forsooth==<br />
An article describes two brands of athletic wear that are claimed to optimize performance via embedded holograms (Power Balance) and water-soluble titanium (Phiten).<br />
<blockquote>“A lot of these products are a sort of merchandized superstition. …. [A French surfer states,] ‘But if wearing the thing makes you think you feel or perform better, who cares?’”<br><br />
<div align="right"><br />
[http://www.time.com/time/magazine/article/0,9171,2021057,00.html “Wrist Watch”], <i>TIME</i>, October 4, 2010<br />
</div><br />
</blockquote><br />
Submitted by Margaret Cibes<br />
<br />
-----<br />
<blockquote>"A scant 1,391 people live in 91008 ZIP code, and only 12 homes are currently on the market. So a single high-priced listing (like the mammoth nine-bedroom, built this year, that's selling for $19.8 million) is enough to skew the median price skyward."<br><br />
<div align="right">[http://realestate.yahoo.com/promo/americas-most-expensive-zip-codes-2010.html America’s Most Expensive ZIP Codes 2010], <br><i>Yahoo! Real Estate</i>, September 27, 2010<br />
</div></blockquote><br />
Note that someone at Forbes must have spotted the potential error in the last 8 words. While the original sentence remains on the Yahoo website, the sentence now ends “may not adequately represent how everyone in the area lives” at the Forbes website[http://www.forbes.com/2010/09/27/most-expensive-zip-codes-2010-lifestyle-real-estate-zip-codes-10-intro.html].<br><br />
<br />
Submitted by Margaret Cibes at the suggestion of Cris Wellington<br />
<br />
----<br />
<blockquote><br />
"The relationship between an area's income and mortality is so striking," the report says, "that on average, every $10,000 increase in an area's median income appears to buy its residents another year of life."<br />
<br><br />
<div align="right"> <br />
[http://www.startribune.com/lifestyle/health/104540289.html?elr=KArksLckD8EQDUoaEyqyP4O:DW3ckUiD3aPc:_Yyc:aUUs Key to long life? It may be in ... your ZIP code]<br>Minneapolis Star Tribune, 7 October 2010 </div><br />
</blockquote><br />
<br />
Submitted by Paul Alper<br />
<br />
==More fuel to feed the fiery controversy over mammograms==<br />
<br />
[http://www.nytimes.com/2010/09/30/health/research/30mammogram.html Mammogram Benefit Seen for Women in Their 40s], Gina Kolata, The New York Times, September 29, 2010.<br />
<br />
One of the most contentious debates in medicine is whether mammograms are beneficial to women between 40 and 50 years old. Earlier commentaries about this controversy appear in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_8#Mammograms_Validated_as_Key_in_Cancer_Fight Chance News 8], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_12#Screening Chance News 12], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_14#Gerd_Gigerenzer.27s_Calculated_Risks_Revisited Chance News 14], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_47#Bayes_theorem_in_the_news Chance News 47], [http://www.causeweb.org/wiki/chance/index.php/Chance_News_58#Mammogram_Math Chance News 58], and [http://www.causeweb.org/wiki/chance/index.php/Chance_News_59#Ill_health_news Chance News 59].<br />
<br />
The first sentence in the latest article about mammography makes a bold claim...<br />
<br />
<blockquote>Researchers reported Wednesday that mammograms can cut the breast cancer death rate by 26 percent for women in their 40s.</blockquote><br />
<br />
...and the second sentence contradicts this claim.<br />
<br />
<blockquote>But their results were greeted with skepticism by some experts who say they may have overestimated the benefit.</blockquote><br />
<br />
The data set on which these bold claims were based is quite good.<br />
<br />
<blockquote>The new study took advantage of circumstances in Sweden, where since 1986 some counties have offered mammograms to women in their 40s and others have not, according to the lead author, Hakan Jonsson, professor of cancer epidemiology at Umea University in Sweden. The researchers compared breast cancer deaths in women who had a breast cancer diagnosis in counties that had screening with deaths in counties that did not. The rate was 26 percent lower in counties with screening.</blockquote><br />
<br />
Why the skepticism?<br />
<br />
<blockquote>One problem, said Dr. Peter C. Gotzsche of the Nordic Cochrane Center in Copenhagen, a nonprofit group that reviews health care research, is that the investigators counted the number of women who received a diagnosis of breast cancer and also died of it. They did not compare the broader breast cancer death rates in the counties.</blockquote><br />
<br />
A prominent statistician, Donald Berry, is also quoted in this article.<br />
<br />
===Questions===<br />
<br />
1. The research design in the current study was not randomized. Is this an issue?<br />
<br />
2. What are the barriers to conducting a randomized trial for mammography?<br />
<br />
==Even more fuel!==<br />
[http://www.healthnewsreview.org/blog/2010/10/this-is-the-way-the-swedish-mammography-study-couldshould-have-been-analyzed.html This is the way the Swedish mammography study could/should have been analyzed]<br><br />
by Gary Schwitzer, HealthNewsReview Blog, 4 October 2010<br />
<br />
Schwitzer's blog (which we first mentioned in [http://www.causeweb.org/wiki/chance/index.php/Chance_News_59#Ill_health_news Chance News 59]) discusses news reports on public health issues, rating the stories according to a set [http://www.healthnewsreview.org/review-criteria.php rubric]. <br />
<br />
His present post concerns the Swedish mammogram study. He reviews the New York Times article described above, as well as reports from the <br />
[http://articles.latimes.com/2010/sep/29/news/la-heb-mammography-20100929 Los Angeles Times], the <br />
[http://www.npr.org/templates/story/story.php?storyId=130053888 Associated Press] and <br />
[http://news.health.com/2010/09/29/mammograms-save-lives-for-women-in-their-40s-study-says/ Health Day]. The last is singled out as the only one of the four that fails to make any mention of methodological concerns. However, Schwitzer goes on to argue that none of the articles does an adequate job explaining the methodological issues or their implications for the conclusions of the study. Read the full post for an interesting extended discussion on this.<br />
<br />
'''Question'''<br><br />
<br />
The discussion in the post notwithstanding, the individual HealthNewsReview ratings cited there give the [http://www.healthnewsreview.org/review.html?review_id=3203 NYT], <br />
the [http://www.healthnewsreview.org/review.html?review_id=3204 LA Times] <br />
and [http://www.healthnewsreview.org/review.html?review_id=3205 AP] <br />
stories 4 stars, 5 stars, and 5 stars (out of 5) respectively. What do you make of this?<br />
<br />
Submitted by Bill Peterson<br />
<br />
==Proofiness==<br />
<br />
Charles Seife is a marvelous writer of serious, interesting topics for the lay reader:<br />
<ul><br />
<li>''Zero: The Biography of a Dangerous Idea'', 2000<br />
<li>''Alpha & Omega: The Search for the Beginning and End of the Universe'', 2004<br />
<li>''Decoding The Universe'', 2007<br />
<li>''Sun in a Bottle: The Strange History of Fusion and the Science of Wishful Thinking'', 2008<br />
</ul><br />
His latest book, ''Proofiness: The Dark Arts of Mathematical Deception'', 2010, makes for especially good reading for students and teachers of statistics. The following web sites all comment on the book: The New York Times has a [http://www.nytimes.com/2010/09/19/books/review/Strogatz-t.html?_r=1&ref=bookreviews review] and an [http://www.nytimes.com/2010/09/16/books/excerpt-proofiness.html?ref=review excerpt]; NPR ran a story, [http://www.npr.org/templates/story/story.php?storyId=129972868 Lies, Damned Lies, And 'Proofiness']; additional reviews appeared<br />
in [http://www.nyjournalofbooks.com/2010/09/proofiness-dark-arts-of-mathematical.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+NewYorkJournalOfBooks+(NEW+YORK+JOURNAL+OF+BOOKS) New York Journal of Books] and [http://www.politicsdaily.com/2010/08/01/proofiness-using-numbers-to-fool-people-and-shape-political-deb/ Politics Daily].<br />
<br />
The reviews are entirely favorable, but don’t quite do justice to his presentation, so readers of Chance News are encouraged to read the book as well as the above commentaries.<br />
<br />
Seife defines proofiness as “the art of using bogus mathematical arguments to prove something that you know in your heart is true — even when it’s not.” However, he never makes the connection to [http://www.innumeracy.com/ Innumeracy] <br />
<blockquote><br />
A term meant to convey a person's inability to make sense of the numbers that run their lives. Innumeracy was coined by cognitive scientist Douglas R Hofstadter in one of his Metamagical Thema columns for Scientific American in the early nineteen eighties. Later that decade mathematician John Allen Paulos published the book Innumeracy. In it he includes the notion of chance as well to that of numbers.<br />
</blockquote><br />
Seife also does not refer to Stephen Colbert’s even more famous neologism, [http://en.wikipedia.org/wiki/Truthiness truthiness] which<br />
<br />
<blockquote><br />
is a "truth" that a person claims to know intuitively "from the gut" without regard to evidence, logic, intellectual examination, or facts.<br />
</blockquote><br />
<br />
Colbert himself put truthiness this way:<br />
"We're not talking about truth, we're talking about something that seems like truth – the truth we want to exist."<br />
<br />
Seife begins his Introduction with the famous quotation of Senator Joseph McCarthy on February 9, 1950:<br />
<br />
<blockquote><br />
"I have here in my hand a list of 205--a list of names that were made known to the Secretary of State as being members of the Communist party and who nevertheless are still working and shaping policy in the State Department."<br />
<blockquote><br />
</blockquote><br />
The 205 later became 57 and then 81. “It really didn’t matter whether the list had 205 or 57 or 81 names. The very fact that McCarthy had attached a number to his accusations imbued them with an aura of truth.” This “outrageous falsehood was given the appearance of absolute fact.”<br />
</blockquote><br />
<br />
Seife attempts to categorize the types of proofiness:<br />
<br />
A. Potemkin numbers--numerical facades that look like real numbers such as crowd estimates or the number of communists in the State Department.<br><br />
B. Disestimation, another neologism--“the act of taking a number too literally, understating or ignoring the uncertainties that surround it.”<br><br />
C. Fruit packing--“it’s not the individual numbers that are false; it is the presentation of the data that creates the proofiness.”<br><br />
D. Cherry picking--a form of fruit packing in which there is a “careful selection of data, choosing those that support the argument you wish to make while underplaying or ignoring data that undermine it.”<br><br />
E. Apples to oranges comparison--another form of fruit packing, for example, comparing dollar amounts without taking into account inflation.<br><br />
F. Apple polishing--another form of fruit packing, for example, deceptive graphs where the origin is missing; or, algebraically, misuse of mean and median.<br><br />
G. Causuistry, another neologism and a pun on the word casuistry--“a specialized form of casuistry where the fault in the argument comes from implying that there is a causal relationship between two things when in fact there isn’t any such linkage.”<br><br />
H. Randumbness, another neologism--“insisting that there is order where there is only chaos” or, “creating a pattern where there is none to see.”<br><br />
I. Regression to the moon--for example, extrapolating instead of interpolating regression results.<br><br />
<br />
None of these categories are new to teachers of statistics but his examples of the above forms of proofiness are detailed and when not frightening, are amusing; these examples include: the O.J. Simpson trial; the Franken-Coleman Minnesota Senate election and Bush vs. Gore in 2000 (he terms them “electile dysfunctions”); nuclear testing; risk analysis; the space program; the Vietnam war; and, determination of the perfect butt (page 66 contains the formula for callipygianness--a word which is '''not''' a neologism). He is particularly incisive when he discusses systematic error when it overwhelms and confuses the notion of error due to sampling, and thus, invalidating the so-called margin of error in polling. <br />
<br />
===Discussion===<br />
<br />
1. If it is so obvious today that McCarthy was fabricating the numbers--in the parlance of today, he was fact-free--why was he so successful so long in the 1950s? And why did his allegations and point of view live on well after his death in 1957?<br />
<br />
2. Seife devotes a great deal of time to convince the reader that the U.S. census would be more accurate if it did not attempt to count everyone but rather did statistical sampling and avoid many of the systematic errors. Why would this be true? Why did the U.S. Supreme Court deem otherwise?<br />
<br />
3. Some of his strongest criticism is directed at journalists and polling organizations. The chapter entitled, “Poll Cats.” On page 120 he says, “Internet polls have no basis in reality whatsoever.” Why? “Yet, CNN.com has an Internet poll on its front page every day.” Again, why? Non Internet polls do not come off much better due to flagrant non-statistical faults.<br />
<br />
4. With regard to the O.J. Simpson murder trial, Seife paraphrases one of Simpson's defense attorney's claim that “only one in a thousand wife-beaters winds up murdering his spouse. One in a thousand! Such a small probability means that O.J. Simpson almost certainly isn’t the murderer, right? “ Use Bayes theorem along with reasonable numbers about the number of wives being murdered to indicate that Simpson’s probability of being the culprit is much higher.<br />
<br />
5. Regression to the moon also refers to totally nonsensical use of regression. A more detailed look (page 66) at callipygianness reveals<br />
<center><br />
Callipygianness = (S + C) x (B + F) / (T - V) ,<br />
</center><br />
where S is shape, C is circularity, B is bounciness, F is firmness, T is texture, and V is waist-to-hip ratio. Seife found this regression result, not surprisingly, on <br />
[http://www.foxnews.com/story/0,2933,191622,00.html Fox News] and the reporter was from another Murdoch enterprise, The New York Post. Why does Seife find this regression result so ridiculous? On the same page, there is a regression result for “Misery” which depends upon weather, debt, motivation, “the need to take action,” and some other variables. “[I]t proved --scientifically--that the most miserable day of the year [2005] was January 24.” The regression result for “Happiness” appears on the preceding page. Why does Seife claim that these three are examples of Potemkin numbers?<br />
<br />
6. To return to McCarthy’s proofiness, his original speech about the 205 communists in the State Department was made in Wheeling, West Virginia to the Republican Women’s Club and made no waves whatsoever for days. Seife does not mention this, but only after the New York Times and the Washington Post publicized the speech did it ignite his fame. Contrast that time lag with today’s instant communication.<br />
<br />
7. Seife on page 226 repeats a famous adage of the journalism world: “If your mother says she loves you, check it out.” He then looks at the Pentagon’s weekly body counts and monthly hamlet evaluations during the Vietnam War. By page 228 he describes an auto-industry market research report which shows that driving a Hummer H3 is “better for the environment than driving the energy-efficient Toyota Prius hybrid.” Why did he juxtapose these two examples?<br />
<br />
8. The last paragraph of the book is: “Mathematical sophistication is the only antidote to proofiness and our degree of knowledge will determine whether we succumb to proofiness or fight against it. It’s more than mere rhetoric; our democracy may well rise or fall by the numbers.” Why might his “antidote” be insufficient?<br />
<br />
Submitted by Paul Alper<br />
<br />
==Sampling saliva==<br />
[http://www.thenation.com/article/154596/freshmen-specimen “Freshmen Specimen”]<br><br />
by Patricia J. Williams, <i>The Nation</i>, September 27, 2010<br> <br />
<br />
In this column, law professor Williams describes reactions to the University of California’s Berkeley project [http://onthesamepage.berkeley.edu/ “Bring Your Genes to Cal”], in which 5500 incoming freshmen were asked to provide saliva samples for the purpose of “bring[ing] the student body together in the same manner that reading To Kill a Mockingbird might have in the past.” More than 700 students submitted their samples to an uncertified Berkeley lab, and the samples were analyzed for “susceptibility to alcoholism, lactose intolerance and relative metabolism of folic acid.”<br><br />
<br />
<blockquote>[T]he California Department of Public Health barred the university from dispensing individual profiles on the grounds that genetic analysis is correlative only and is neither necessarily predictive nor diagnostic at this point. A collective comparison of the class's genetic data was permitted, however, and circulated in "anonymized" form at orientation.</blockquote><br />
<br />
Some ethical issues that have been raised include:<br><br />
(a) privacy, despite the “anonymizing” of results;<br><br />
(b) ownership of the data with respect to commercialization, patentability, remuneration, <i>etc.</i>;<br><br />
(c) promotion of the concept that a genetic correlation is a “100 percent infallible guarantee” of anything;<br><br />
(d) motive with respect to promoting sales of swab kits.<br><br />
<br />
The article refers to a Stanford University medical school class “spit party” and to a University of Minnesota [http://www.peds.umn.edu/gopherkids/ "Gopher Kids"] program (free gifts for saliva swabs at a state fair).<br />
<br />
Readers might be interested in a paper from ETC Group, a Canadian-based international organization, [http://www.etcgroup.org/upload/publication/675/02/genomixspitkits_03march08.pdf "Direct-to-Consumer DNA Testing and the Myth of Personalized Medicine: Spit Kits, SNP Chips and Human Genomics"]. Or they might want to google "spit party" to see how widespread these activities are.<br />
<br />
===Discussion===<br />
<br />
1. Explain what the Public Health Department meant by the clause "genetic analysis is correlative only." <br />
<br />
2. Comment on the following statement in the article: “The university advertises participation as altruistic, a contribution to public health and human knowledge.”<br><br />
<br />
3. The author of the article refers to the process of collecting saliva samples as a “commodity exchange.” Do you agree with the author?<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Correlation as investment tool==<br />
[http://online.wsj.com/article/SB10001424052748704129204575505550134652416.html?KEYWORDS=jonnelle+marte “Why the Math of Correlation Matters”]<br><br />
by Jonnelle Marte, <i>The Wall Street Journal</i>, October 4, 2010<br><br />
<br />
This article discusses how a mutual-fund investor might employ the concept of correlation in aiming to diversify, and/or reduce volatility in, an investment portfolio. <br />
<br />
<blockquote>“If your investments move in lock step, or are highly correlated, "you'll either be all right or all wrong," says [an equity market strategist].</blockquote><br />
<br />
It describes how correlation is measured in comparing two investments: <br />
<blockquote>A correlation close to zero means the performance of one asset has little or no connection to that of the other. A correlation of 1 is a perfect positive correlation, meaning the two assets always move in sync—in the same direction, and at a scale that doesn't vary. For instance, Asset A will always move at twice the magnitude of Asset B. A correlation of minus 1 is a perfect negative correlation. The assets move in opposite directions at a scale that doesn't vary.</blockquote><br />
<br />
And it points out that daily, weekly, or monthly returns can be compared, and provides a table of correlations of various assets to the S&P 500 over a 10-year period. At the extremes are a +0.89 correlation between international stocks and the S&P, versus a -0.39 correlation between intermediate U.S. bonds and the S&P.<br> <br />
<br />
There are two caveats. The term of the analysis is a key consideration; for example, the 10-year correlation of -0.39 referred to above became a +0.08 correlation for an over-80-year period. Also, a crisis, such as the 2008 “crash,” may result in a “surge” in correlations, when investments of all kinds decreased.<br><br />
<br />
The author states that investors may choose assets that are uncorrelated, or negatively correlated, to the S&P 500, in order to balance, or minimize, risk.<br />
<blockquote>Such strategies are only recommended in the short term because they essentially cancel out returns. Holding too many negatively correlated assets can be a little like trying to hit the gas while slamming on the brakes, says [one financial analyst].</blockquote><br />
<br />
Interested readers are directed to the website [http://assetcorrelation.com "Asset Correlations"], where they will find a table of correlations between pairs of asset categories, or they may create their own tables.<br><br />
<br />
Two bloggers commented[http://online.wsj.com/article/SB10001424052748704129204575505550134652416.html?KEYWORDS=jonnelle+marte#articleTabs%3Dcomments]:<br><br />
<br />
(a) "This is NOT the way correlation works!!<br><br />
"A correlation of negative one does NOT mean that when asset class A returns 5%, asset class B returns negative 5%. It means that when asset class A returns greater than its expected return (say expected return of 5% and A is returning 7%), then asset class B will be return less than its expected return (if asset class B also has an expected return of 5%, then it would be returning 3%)."<br><br />
<br />
(b) "Good point. To summarize, correlation indicates if variables tend to move in the same direction, but gives no indication about the amplitude of these movements."<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Money isn’t everything, at least in baseball==<br />
[http://online.wsj.com/article/SB10001424052748703743504575493942146685242.html?KEYWORDS=matthew+futterman “The Year Money Didn’t Matter”]<br><br />
By Matthew Futterman, <i>The Wall Street Journal</i>, September 16, 2010<br><br />
<br />
This article reports that the correlation between Major League Baseball player payrolls and games won will be at its lowest level (0.14) since the 1994 players’ strike, if “current standings hold up through the end of the season.” And it contains a graph of correlations for the period 1995-2010 to date.<br><br />
<br />
http://sg.wsj.net/public/resources/images/WK-AV449_BASEBA_NS_20100916175614.gif<br />
<br />
While all eight teams reaching the playoffs had among the 10 top payrolls in 1999, only three of the highest payroll teams – but four of the lowest – will probably make the 2010 playoffs, if standings hold up through the end of this season.<br><br />
<br />
Despite the fact that top and bottom payrolls have grown farther apart in dollars, one factor in the current situation may be the 2002 revenue-sharing agreement, by which wealthier ball clubs now share increasing amounts of revenue with poorer clubs. Some of the revenue-receiving poorer teams have invested in non-payroll expenses such as scouting, trades, <i>etc</i>., with resulting improvements in performance, while some of the revenue-contributing teams’ performances have been constrained by long-term contracts with under-performing players, as well as by player injuries this year.<br><br />
See more data:<br><br />
(a) <i>Forbes</i> blog on 2010 baseball costs per win in [http://blogs.forbes.com/sportsmoney/2010/10/04/baseballs-most-and-least-efficient-teams-for-the-2010-season/ “Baseball’s Most and Least Efficient Teams for the 2010 Season”]<br><br />
(b) <i>New York Times</i> chart of payrolls vs. win-loss records over the period 2001-2010 in [http://www.nytimes.com/interactive/2010/09/26/sports/20090926-score-graphic.html “Putting a Price Tag on Winning”]<br><br />
(c) ESPN chart and table of payrolls vs. win-loss records over the period 1998-2008 in [http://sports.espn.go.com/espnmag/story?id=3816824 “The Biz: The Price of Winning”]<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
==Medical misinformation==<br />
[http://www.theatlantic.com/magazine/archive/2010/11/lies-damned-lies-and-medical-science/8269/ Lies, damned lies, and medical science]<br><br />
by David H. Freedman, ''The Atlantic'', November 2010<br />
<br />
To be continued...<br />
<br />
==World Statistics Day==<br />
<br />
See the U.S. Census Bureau website[http://www.census.gov/newsroom/releases/archives/news_conferences/2010-10-20_worldstats.html] for videos and other information related to the first World Statistics Day: October 20, 2010.<br> <br />
<br />
Note that the date, written in day/month/year format, is 20/10/2010. It will be interesting to see how the day is chosen in year 2013 or subsequent years.<br><br />
<br />
Submitted by Margaret Cibes<br />
<br />
<br />
==Racial disparity in Wikimedia Commons photos==<br />
<br />
A short article was [http://www.examiner.com/wiki-edits-in-national/racist-undertones-on-wikipedia published October 20] on Examiner.com, drawing attention to a racial disparity found in two distinct sections of freely-licensed visual content published at Wikimedia Commons (a sister site of Wikipedia). While the subject matter of the photos may make some uncomfortable, the parent Wikimedia Foundation did in fact [http://www.examiner.com/wiki-edits-in-national/wikimedia-foundation-rules-on-naughty-bits hire a consultant] to evaluate the situation from an independent perspective. <br />
<br />
What is boils down to is that the consultant said he evaluated 1,000 images of male sex organs that are found on Wikimedia Commons, and (by his count) not a single one was of a non-white male. In another (much smaller) category of photos and illustrations called "[http://commons.wikimedia.org/wiki/Category:Topless_adolescent_girls topless adolescent girls]", some 25 of the 26 images portray non-white subjects. <br />
<br />
As the Examiner article asks, is this a tacit form of racism? The odds that these two categories ''coincidentally'' ending up 99.9% white and 96.2% non-white, respectively, seem too hard to imagine.<br />
<br />
* What other factors might explain why a racial disparity is found in these categories?<br />
* Do you see any problematic factors in how a collection of encyclopedic images are gathered, when there is no editorial board guiding acquisition?<br />
<br />
Submitted by Gregory Kohs</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=13246Chance News 312010-06-22T15:08:16Z<p>Thekohser: /* The Unbreakable Wikipedia? */ Fixed link</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 are non-white, with Inter fielding, 19,<br> Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
* This issue has been covered in the BBC radio 4 series [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7078555.stm More or Less.]<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/dpp/news/Univ_of_Minnesota_Less_Than_12_Percent_of_Wikipedia_Content_is_Damaged Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state. However, the problem is clearly growing:<br />
<br />
<center>http://www.mywikibiz.com/images/2/21/DamagedViews.jpg</center><br />
<br />
It is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our assessment is that the Minnesota study would have accepted a passage like this as completely "undamaged".<br />
<br />
From the "[http://www.mywikibiz.com/Worst_of_Wikipedia/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
===Potential bias in the study===<br />
'''1. From the study:'''<br />
<blockquote><br />
''We assume that one serving of an article by a Wikipedia server is a reasonable proxy for one view of that article by a user.''</blockquote><br />
:'''Critique:'''<br />
Humans don't read the entire article every time they load one in their browser. [http://www.poynterextra.org/eyetrack2004/main.htm Studies have shown] that readers of web pages tend to focus most of their priority on the top-left portion of the page. Therefore, this study is giving equal weight to words that appear at the bottom of an article, even though there is disproportionate reader emphasis on the first paragraph or two of any Wikipedia article.<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to bury his content in the middle or toward the end of Wikipedia articles, though fewer people being served the article would actually read his content.<br />
<br><br><br />
'''2. From the study:'''<br />
<blockquote><br />
''A tempting proxy for article views is article edits. However, we found essentially no correlation between views and edits in the request logs.''</blockquote><br />
:'''Critique:'''<br />
Why was there "essentially no correlation"? Popular, often-viewed pages on Wikipedia (examples include the articles about [http://en.wikipedia.org/wiki/Wiki wiki], [http://en.wikipedia.org/wiki/Chris_Benoit Chris Benoit], [http://en.wikipedia.org/wiki/Ann_Coulter Ann Coulter], [http://en.wikipedia.org/wiki/List_of_sex_positions List of sex positions], and [http://en.wikipedia.org/wiki/Jeff_Hardy Jeff Hardy]) are frequently semi-protected (only registered users with 4 days of experience may modify the article) or fully-protected (only administrators may access the edit feature). In fact, the above articles have all appeared in Wikipedia's "10 most popular articles of the month" list, and all remain protected from free editing. Therefore, a very powerful ''inverse'' relationship between views and edits would exist for [http://tools.wikimedia.de/~leon/stats/wikicharts/index.php?ns=articles&limit=100&month=08%2F2006&wiki=enwiki Wikipedia's most popular pages]; which probably topples the otherwise intuitive correlation between article views and article edits. Are the study's authors cognizant of this?<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add his content to contentious, popular articles, just before they are "locked down" from further editing. A Wikipedia administrator would have the capacity to make substantial edits to an article just before himself locking down (or asking an admin colleague to lock down) the very same article.<br />
<br><br><br />
'''3. From the study:'''<br />
<blockquote><br />
''...if a contribution is viewed many times without being changed or deleted, it is likely to be <s>a</s> valuable.''</blockquote><br />
:'''Critique:'''<br />
Or, equally likely, the contribution is not being read critically, or even read at all. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add content that is wordy, boring, and dense. Prose that intimidates or sedates the reader would be so bland as to encourage skimming (rather than editing!), every time it is viewed.<br />
<br><br><br />
'''4. From the study:'''<br />
<blockquote><br />
''Our software does not track persistent words if text is "cut-and-pasted" from one article to another. If an editor moves a block of text from one article to another, PWVs after the move will be credited to the moving editor, not to the original editors.''</blockquote><br />
:'''Critique:'''<br />
Large credit goes, then, to "text movers" rather than "text creators". People who move a lot of text around will typically be busy-body administrators, rather than the careful scholars who painstakingly wrote the material in the first place. It is a known fact that the busiest administrators do a lot of "tidying" of major articles which lack any trace of their own content. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to become an administrator, then move a bunch of well-written content from article to article, which is frequently done among articles like "History of Tuscany" to "History of Italy" to "History of the Mediterranean" to "History of Europe" to the God-awful "History of western Eurasia".<br />
<br><br><br />
'''5. From the study:'''<br />
<blockquote><br />
''We exclude anonymous editors from some analyses, because IPs are not stable: multiple edits by the same human might be recorded under different IPs, and multiple humans can share an IP.''</blockquote><br />
:'''Critique:'''<br />
The same could be said for registered user accounts, which can be used from different IP addresses, by different people who know the password. It is a fact that some contributors to this very Chance News wiki are known to share registered Wikipedia user accounts. Regardless, the study itself found that anonymous IPs made 9 trillion edits out of a total of 34 trillion. Why would the study therefore exclude over 26% of the sample? This would have the effect of elevating the relative strength of contributions by a finite number of registered accounts, which is exactly what the study concludes. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to set up an account that he then shares with other like-minded individuals, so that more round-the-clock editing is possible, thereby building credibility in the community as a "dedicated Wikipedian". <br />
<br><br><br />
'''6. From the study:'''<br />
<blockquote><br />
''Reverts take two forms: '''identity revert''', where the post-revert revision is identical to a previous version, and '''effective revert''', where the effects of prior edits are removed (perhaps only partially), but the new text is not identical to any prior revision. ...In this paper, we consider only identity reverts.''</blockquote><br />
:'''Critique:'''<br />
Identity reverts, since they are a "button" tool that may seem intimidating to an average user, are probably more likely to be used by administrators, not scholars. Therefore, this study again gives extra strength to the actions of mop-wielding admins, rather than earnest shapers of Wikipedia. <br />
:'''Gaming the system:'''<br />
To count for more in this study, you wouldn't ever want to work to "improve" fixable recent content in Wikipedia. Rather, revert it, then re-write it in your own words.<br />
<br><br><br />
'''7. From the study:'''<br />
<blockquote><br />
''We believe it is reasonable to assume that essentially all damage is repaired within 15 revisions.''</blockquote><br />
:'''Critique:'''<br />
This may be so, but Figure 8 in the report also shows that 20% of the "Damaged-Loose" content incidents in Wikipedia are viewed by at least 30 people before they get fixed. Ten percent of such mistakes are viewed by well over 100 people before repaired. <br />
:'''Gaming the system:'''<br />
Learning to write mistaken or vandalistic prose in such a way that many, many people read it without "noticing" that it is wrong would be a way to further extend the time and views until detection. The libelous content written about [http://en.wikipedia.org/wiki/Seigenthaler_controversy John Seigenthaler, Sr.] and about [http://en.wikipedia.org/wiki/Fuzzy_Zoeller#Controversies Fuzzy Zoeller] went unnoticed for a number of weeks or months without causing any alarm. An effective way to make unsuspecting readers believe a lie in Wikipedia is to show a reference citation next to the false content. The reference need not even link to a source making the same claim you are making.<br />
<br />
==Rudy wrong on cancer survival chances==<br />
The [http://blog.washingtonpost.com/fact-checker/2007/10/rudy_miscalculates_cancer_surv.html ''Washington Post Fact Checker'', Oct. 30, 2007]<br><br />
Michael Dobbs<br />
<br />
This Blog describes its goal as follows:<br />
<br />
<blockquote>Our goal is to shed as much light as possible on controversial claims and counter-claims involving important national issues and the records of the various presidential candidates.</blockquote><br />
<br />
Here they discuss Giuliani’s New Hampshire radio advertisement, October 29, 2007.<br />
<br />
<blockquote>I had prostate cancer, five, six years ago. My chances of surviving prostate cancer and thank God I was cured of it, in the United States, 82 percent. My chances of surviving prostate cancer in England, only 44 percent under socialized medicine.</blockquote><br />
<br />
It is not clear what is being compared here. It is probably meant to be the survival rate. This is defined by the National Cancer Institution as: <br />
<br />
<blockquote>The percentage of people in a study or treatment group who are alive for a given period of time after diagnosis. This is commonly expressed as 5-year survival.</blockquote><br />
<br />
The Giuliani campaign reports that these percentages came from an article in [http://www.city-journal.org/html/17_3_canadian_healthcare.html ''City Journal''], a publication of the Manhattan Institute, a conservative research organization. This article, ''The Ugly Truth About Canadian Health Care'', was written by Dr. Lavid Gratzer, a senior fellow at the Manhattan Institute and an adviser for the Giuliani campaign. While the article did not say where the numbers came from, Dr. Gratzer has now explained that they came from a Commonwealth Fund article<br />
''Multination Comparisons of Health Systems Data, 2000'' by Gerard F. Anderson and Peter S. Hussey of Johns Hopkins University. Specifically they came from this graphic in the Commenwealth Fund article:<br />
<br />
<center> http://www.dartmouth.edu/~chance/forwiki/prostate.jpg</center><br />
<br />
The Commonweath Fund provided a [http://www.commonwealthfund.org/newsroom/newsroom_show.htm?doc_id=568333 a Statement] in repsonse to Giuliani’s advertisement. They say:<br />
<br />
<blockquote>The incidence rates simply report the number of men diagnosed with prostate cancer in a given year. Prostate cancer mortality rates report the number of men who died of the disease in a given year. Neither speaks to length of survival, and that figure can not be calculated using the others. </blockquote> <br />
<br />
But Dr. Gratzer defends Guiliani's ad in an article "On cancer survival rates, Rudy’s right and his critics are wrong" ''City Journal'', 31 October 2007. Here we read: <br />
<br />
<blockquote>Let me be very clear about why the Giuliani campaign is correct: the percentage of people diagnosed with prostate cancer who die from it is much higher in Britain than in the United States. The Organization for Economic Co-operation and Development reports on both the incidence of prostate cancer in member nations and the number of resultant deaths. According to OECD data published in 2000, 49 Britons per 100,000 were diagnosed with prostate cancer, and 28 per 100,000 died of it. This means that 57 percent of Britons diagnosed with prostate cancer died of it; and, consequently, that just 43 percent survived.</blockquote><br />
<br />
Finally, from the Washington Post Blog we read:<br />
<br />
<blockquote>UPDATE: Maria Comella, deputy communications manager for the Giuliani campaign, sent us the following e-mail explaining the mayor's mistake without quite acknowledging it: <blockquote>Mayor Giuliani is an avid reader of ''City Journal'' and found the passage in the Gratzer article himself. He cited the statistics at a campaign stop, and the campaign used a recording from that appearance in the radio ad. The citation is an article in a highy respected intellectual journal written by an expert at a highly respected think tank which the mayor read because he is an intellectually engaged human being.</blockquote><br />
<br />
===Discussion===<br />
<br />
(1) Do you agree with the Commonwealth Fund statement?<br />
<br />
(2) Do you agree with Gretzer's explanation?<br />
<br />
(3) Others say that the difference is caused by the fact that the United States screens for Prostate Cancer earlier than England does so of course the survival rate will be longer. Is this relevant to this controversy?<br />
<br />
==More or less==<br />
[http://www.ft.com/cms/s/0/52e30ae6-9191-11dc-9590-0000779fd2ac.html Lunch with the FT: Andrew Dilnot,] by Tim Harford, The Financial Times, 16 Nov 2007.<br />
<br />
Chance readers may be interested in a BBC Radio 4 series called [http://news.bbc.co.uk/1/hi/programmes/more_or_less/ <em>More or less</em>,] which is about numbers in the news.<br />
(The original presenter [http://en.wikipedia.org/wiki/Andrew_Dilnot Andrew Dilnot] recently <br />
[http://www.ft.com/cms/s/0/52e30ae6-9191-11dc-9590-0000779fd2ac.html stepped down]<br />
to be replaced by [http://www.timharford.com/ Tim Hartford,] <br />
who writes the 'Dear Economist' column for the Financial Times.)<br />
<br />
The website for the programme gives a hint at the topics covered:<br />
* [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7101633.stm predicting bird flu]<br />
* [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7090524.stm measuring happiness]<br />
* [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7078555.stm migrant figures that do not add up] (covered in a Chance news article in this issue)<br />
* [http://open2.net/sciencetechnologynature/maths/coincidence.html The dangers of spotting patterns in random things]<br />
<br />
Dilnot says that in the radio show<br />
<blockquote><br />
We are trying to show people how they can interpret the numbers that are thrown at them.<br />
</blockquote><br />
He advises people to ask simple questions, such as: <em>Is that a big number?</em><br />
In the interview by Harford, Dilnot claims that <br />
the worst social statistic of all time was that <br />
<em>the number of children killed in the United States has doubled every year since 1953</em>.<br />
<br />
One simple trick is to try to humanize statistics, Dilnot claims:<br />
<blockquote><br />
Faced with a question such as: <em>how many petrol (gasoline in the US) stations are there in the UK?</em>, ask yourself how many petrol stations there are in your town, and how many people. It’s the first step towards grasping a sensible answer to the bigger question.<br />
</blockquote><br />
<br />
Dilnot has written that just about the only question that can’t be partially answered with reference to personal experience is: <em>how many penguins are there in Antarctica?</em> due to the difficulties of a credible penguin census.<br />
<br />
===Questions===<br />
* What is wrong with the claim that <em>the number of children killed in the United States has doubled every year since 1953</em>? <br />
* What is your estimate of how many penguins there are in Antarctica? What bounds do you wish to put around your estimate?<br />
<br />
===Further reading===<br />
* More or Less can be heard on Mondays on BBC Radio 4 at 16:30 BST and is presented by Tim Harford.<br />
** More or Less is a permanent part of the schedule with two series annually, one in the summer, one in winter. <br />
** Here is a link to [http://www.bbc.co.uk/radio/aod/mainframe.shtml?http://www.bbc.co.uk/radio/aod/radio4_aod.shtml?radio4/moreorless the most recent version].<br />
** Since January 2005, it has been produced in association with [http://www.open2.net/moreorless/ the Open University,] who provide links to related webpages, such as: [http://open2.net/sciencetechnologynature/maths/statisticsmedia.html Statistics and the media] and [http://open2.net/sciencetechnologynature/maths/statistics.html Guide to statistics.]<br />
* [http://plus.maths.org/issue45/features/tiger/index.html The Tiger That Isn’t,] Andrew Dilnot's recent book covering similar topics to the radio show.<br />
** Plus Magazine offer a [http://plus.maths.org/issue45/reviews/book2/ review of this book.]<br />
* [http://www.amazon.co.uk/Undercover-Economist-Tim-Harford/dp/0316732931 The Undercover Economist,] a recent book by the new presenter, Tim Harford.<br />
<br />
Submitted by John Gavin.<br />
<br />
==Name-Letter-Effect==<br />
An article in Psychological Science, Volume 18 Issue 12 Page 1106-1112, December 2007 by Nelson and Simmons has received much attention in the lay press, including, Sports Illustrated, Newsweek and USA Today. From the abstract of the article: "we found that people like their names enough to unconsciously pursue consciously avoided outcomes that resemble their names." In other words, as USA Today put it in its headline, "My name made me do it." Put another way, instead of astrology with its alignment of the stars at birth causing your success or failure, it is the name given to you that predicts behavior.<br />
<br />
The article discusses five studies. The "it" in the first study refers to Major League Baseball players who have an initial "K"-the symbol for recording strikeouts--strike out more often, 18.8%, than players with other initials, 17.2%. This study looked at 6397 players who had at least 100 at bats. A hypothesis test was performed and the authors state that "t(6395) = 3.08," yielding a p-value of ".002." However, using the same database, a [http://sabermetricresearch.blogspot.com Blogger] found otherwise; in particular, for 1960s to 2000s: Ks 14.5%, non-Ks 14.2%. This blogger concludes with, "So the big question remains: why did the authors get such a high strikeout rate difference?"<br />
<br />
Here is why: Nelson and Simmons did not do the customary hypothesis test of difference in proportions but instead did a hypothesis test of the difference in means. That is, a batter's strikeout to at bat ratio was not weighted by the number of at bats.<br />
<br />
The "it" in the second study refers to MBA academic performance at an unnamed institution. Looking at about 15,000 students, "As predicted, students whose names begin with a C or D earned lower GPAs than students whose names begin with A or B, F(4, 14348) = 4.55" yielding a p-value of ".001." The effect size is teeny and somehow, those whose initials are E through Z actually have the highest average GPAs.<br />
<br />
===Discussion===<br />
<br />
1. Baseball is full of slang. Two common terms for striking out are "fanning" and "whiffing." Obtain [http://www.baseball-databank.org/ the data set] and do a test for F or W to see what p-value ensues.<br />
<br />
2. The figure below is Fig. 1 in the original paper where the GPAs of A, B, C, D, and Other are displayed. Why is the graph misleading?<br />
<br />
<center> http://www.dartmouth.edu/~chance/forwiki/Figure1.jpg</center><br />
<br />
<center>Fig. 1. Results of Study 2: grade point average <br><br />
as a function of the student's initial. Error bars in...</center><br />
<br />
3. The "it" in a third study looks at 492,458 lawyers at 170 law schools. The dependent variable is law-school quality which varies from Tier 1 (best), Tier 2, Tier 3, Tier 4 (worst). The independent variable is "the proportion of lawyers with initials A and B (relative to lawyers with initials C and D)." The regression result was a slope of -.17 yielding a p-value of .036. The authors conclude, "It seems that people with names like Adlai and Bill tend to go to better law schools that do those with names like Chester and Dwight." Comment on the qualitative nature of the dependent variable and how regression might be affected. Comment on Bill.<br />
<br />
4. The Newsweek writer notes that "the GPA gap is tiny-3.34 versus 3.36." She then claims, "But there is a saying in science that if you discover a way to levitate objects with your thoughts by one millimeter, you don't focus on the millimeter-the size of the effect-but on the fact that something happened at all." Defend and criticize her statement.<br />
<br />
Submitted by Paul Alper</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_49&diff=7724Chance News 492009-06-16T15:22:12Z<p>Thekohser: /* Meteorite hits boy */</p>
<hr />
<div>==Quotations==<br />
<blockquote>Probability arises from an opposition of contrary chances or causes, by which the mind is not allowed to fix on either side, but is incessantly tost [sic] from one to another, and at one moment is determined to consider an object as existent, and at another moment as the contrary.</blockquote><br />
<div align=right>David Hume<br><br />
<br />
</div align=right><br><br />
<br />
Submitted by Margaret Cibes <br />
<br />
After reading the above, I coincidentally came across this David Hume quotation on page 72 of Gould's ''The Mismeasure of Man,'' second edition:<br><br />
<br />
<blockquote>I am apt to suspect the negroes and in general all the other species of men...to be naturally inferior to the whites. There never was a civilized nation of any other complexion than white, nor an individual eminent either in action or speculation. No ingenious manufacturers amongst them, <br />
no arts, no sciences.</blockquote><br />
The quotation continues on in the same vein and makes one's head spin at the attitudes and prejudices of the famous philosophers.<br />
<br />
Submitted by Paul Alper<br />
<br />
==Forsooths==<br />
<br />
<center>http://www.dartmouth.edu/~chance/forwiki/poll.gif</center><br />
-----<br />
[http://freakonomics.blogs.nytimes.com/2009/06/05/when-to-rob-a-bank/ Steven J. Dubner of the New York Times] writes about Bernice Geiger, a person who "never took vacations" for fear of her embezzlement being discovered by a fill-in employee; she "was arrested in 1961 for embezzling more than $2 million over the course of many years." Eventually, "after prison Geiger went to work for a banking oversight agency to help stop embezzlement."<br />
<br />
Geiger's "biggest contribution: looking for employees who failed to take vacation. This simple metric turned out to have strong predictive power in stopping embezzlement."<br />
<br />
Submitted by Paul Alper<br />
<br />
-----<br />
<br />
==Infuse and Kuklo II==<br />
<br />
[http://plus.maths.org/issue9/features/benford/ This web site provides a wonderful pun] regarding Benford’s Law, “Looking out for number one.” The authors write:<br />
“Go and look up some numbers. A whole variety of naturally-occurring numbers will do. Try the lengths of some of the world's rivers, or the cost of gas bills in Moldova; try the population sizes in Peruvian provinces, or even the figures in Bill Clinton's tax return. Then, when you have a sample of numbers, look at their first digits (ignoring any leading zeroes). Count how many numbers begin with 1, how many begin with 2, how many begin with 3, and so on - what do you find? <br />
You might expect that there would be roughly the same number of numbers beginning with each different digit: that the proportion of numbers beginning with any given digit would be roughly 1/9. However, in very many cases, you'd be wrong!”<br />
<br />
Instead, we get <br />
<br />
<center>http://www.dartmouth.edu/~chance/forwiki/LeedingDidgit.gif</center><br />
<center> Figure 1: The proportional frequency of each leading digit predicted by Benford's Law.</center><br />
<br />
Should somebody try “to falsify, say, their tax return then invariably they will have to invent some data. When trying to do this, the tendency is for people to use too many numbers starting with digits in the mid range, 5,6,7 and not enough numbers starting with 1. This violation of Benford's Law sets the alarm bells ringing.”<br />
<br />
It is a pity that unlike for accounting data, there is no forensic counterpart to Benford’s Law for determining when a journal article is entirely fraudulent. As stated in [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_48#Infuse_and_Kuklo Infuse and Kuklo] you won’t be able to read [on the JBJS website] the fraudulent article, “Recombinant human morphogenetic protein-2 for type grade III open segmental tibial fractures from combat injuries in Iraq” by Timothy Kuklo, et al, which appeared in the JBJS in August, 2008 because it has been retracted. However, [http://graphics8.nytimes.com/packages/pdf/business/20090513kuklo-journal-article.pdf it is available here.] The immediate impression is that as far as statistics is concerned, it looks like any other article in the health field.<br />
<br />
The important statistics appear in Tables 1 and III <br />
<br />
http://www.dartmouth.edu/~chance/forwiki/Table1.jpg <br />
<br />
http://www.dartmouth.edu/~chance/forwiki/Table3.gif<br />
<br />
Note that there is no claim that everyone in Group 2 (the group using Infuse) did well or that everyone in Group 1 fared poorly. Further, as in legitimate studies, there are patients who were not included because of an additional problem (head injury) or were lost to follow up. The data is there for reviewers and others to do the calculations which in this paper are the difference in proportions, a standard statistical technique. Small but not immodest p-values indicate that statistical significance is obtained; detailed discussion about the fractures indicates that practical significance is also realized. The bibliography has 39 entries, only one of which has Kuklo as the author; the same entry includes one of the ghost co-authors in the retracted paper. Nothing statistically or otherwise suspicious whatsoever.<br />
<br />
Freudian psychology is currently out of favor but Freud's notion of a [http://www.thetruthseeker.co.uk/article.asp?ID=1602 death wish] still seems plausible. How else to explain the pushing of the envelope past falsification of data, denial of connection to the manufacturers of Infuse, and forging of not one, not two but four ghost authors? The aptly titled 1995 book by Feinberg and Tarrant, ''Why Smart People Do Dumb Things,'' attributes such behavior to what they deem “the four pillars of stupidity”: hubris, arrogance, narcissism and unconscious need to fail. The first three are overwhelmingly obvious, but the last named cause sounds deeply Freudian.<br />
<br />
[http://www.nytimes.com/2009/06/06/business/06surgeon.html A New York Times update] appears on June 5, 2009 and shows how Kuklo forged the signatures; “He used a distinctively different handwriting style for each of them, a form he submitted to the British journal shows.”<br />
<br />
http://www.dartmouth.edu/~chance/forwiki/Kuklosignatures.jpg <br><br />
<br />
Dr. Timothy R. Kuklo and copies of the signatures of other Army doctors on his study that authorities say he forged.<br />
<br />
A putative co-author “suspected that Dr. Kuklo had fabricated the comparison groups, because many soldiers had received both Infuse and a bone graft — not one or the other.” This person said, “It was like he was comparing apples and oranges. But there weren’t any apples or oranges to compare.”<br />
<br />
Returning to the statistical aspect of the paper, Table III says 19 of 67 (28%) in Group 1 were patients who had further surgery while 5 of 62 (8%) in Group 2 (Infuse group) had further surgery. Presumably, via a chi-square test, the p-value is listed as .003. Minitab produces the same numerical result of .003 via the Fisher exact test:<br />
<br />
<br />
Sample X N Sample p<br><br />
1 5 62 0.080645<br><br />
2 19 67 0.283582<br><br />
<br />
<br />
Difference = p (1) - p (2)<br><br />
Estimate for difference: -0.202937<br><br />
95% CI for difference: (-0.330382, -0.0754923)<br><br />
Test for difference = 0 (vs not = 0): Z = -3.12 P-Value = 0.002<br><br />
<br />
Fisher's exact test: P-Value = 0.003<br />
<br />
Some numerical discrepancies arise, however, for Table I. Table I says 51 of 67 (76%) in Group 1 had a successful “union” while 57 of 62 (92%) in Group 2 (Infuse group) had a successful union. Presumably, via a chi-square test, the p-value is listed as .015. Minitab produces the following indicating that because of the small sample sizes, the Fisher exact test yields .017 instead:<br />
<br />
Sample X N Sample p<br><br />
1 57 62 0.919355<br><br />
2 51 67 0.761194<br><br />
<br />
<br />
Difference = p (1) - p (2)<br><br />
Estimate for difference: 0.158161<br><br />
95% CI for difference: (0.0356210, 0.280701)<br><br />
Test for difference = 0 (vs not = 0): Z = 2.53 P-Value = 0.011<br><br />
<br />
Fisher's exact test: P-Value = 0.017<br />
<br />
Table I also says 10 of 67 (14%) in Group 1 had post-operative infections while 2 of 62 (3.2%) in Group 2 (Infuse group) had post-operative infections. Presumably, via a chi-square test, the p-value is listed as .001. Minitab produces the following quite different p-value of .032:<br />
<br />
Sample X N Sample p<br><br />
1 10 67 0.149254<br><br />
2 2 62 0.032258<br><br />
<br />
<br />
Difference = p (1) - p (2)<br><br />
Estimate for difference: 0.116996<br><br />
95% CI for difference: (0.0210037, 0.212988)<br><br />
Test for difference = 0 (vs not = 0): Z = 2.39 P-Value = 0.017<br><br />
<br />
Fisher's exact test: P-Value = 0.032<br />
<br />
However, these discrepancies are hardly in the Benford class. They may merely indicate what happens when a non-statistician medical doctor acts alone.<br />
<br />
Submitted by Paul Alper<br />
<br />
==Emotional biases in financial decisions==<br />
[http://online.wsj.com/article/SB10001424052970203334304574161431391944464.html "Control Yourself"], by Veronica Dagher, The Wall Street Journal, June 8, 2009<br><br />
<br />
This article describes 5 "biases", or emotional issues, that affect investment decisions and that are studied in the field of "behavioral finance."<br><br />
<br />
(1) "Anchoring" bias refers to being "overly attached to a particular investment."<br><br />
(2) "Recency" bias refers to assuming that "events or patterns in the past will continue into the future."<br><br />
(3) "Loss aversion" bias refers to "hoping inaction [will] eventually make the losses go away."<br> <br />
(4) "Endowment effect" bias refers to assigning a "greater value to what [one] own[s] than to what [one doesn't] own, whether that value is warranted or not."<br><br />
(5) "Overconfidence" bias refers to excessive trading in an attempt to "beat the market."<br><br />
<br />
<blockquote>“One could try to explain all the events of the last several months with models and ratios, but it’s become more and more difficult to do so,” says Richard Thaler, professor of behavioral science and economics at the Booth School of Business at the University of Chicago.</blockquote><br />
<br />
Submitted by Margaret Cibes<br><br />
<br />
==Guesstimation==<br />
[http://www.nytimes.com/2009/03/31/science/31angi.html?scp=1&sq=biggest%20puzzles&st=cse The biggest of puzzles brought down to size]. <br><br />
New York Times, 30 March 2009 <br><br />
Natalie Angier<br />
<br />
The article opens by reminding us that with bank bailouts running hundreds of billions of dollars the national debt passing ten trillion, the public need help comparing the magnitudes of really large numbers. For practice, the author recommends so-called &quot;Fermi problems,&quot;. Named for Enrico Fermi, these are estimation problems that physicists and engineers like to use to sharpen their intuition. Two examples cited in the article are: <br />
<br />
<blockquote><br />
What is the total volume of human blood in the world? or, If you put all the miles that Americans drive every year end to end, how far into space could you travel?<br />
</blockquote><br />
<br />
Readers may recall that a number of such problems were described by John Allen Paulos in his classic, ''Innumeracy'', where he lamented the fact that estimation skills were not being taught in the schools. A more recent source, featured in the present article, is ''Guesstimation: Solving the World’s Problems on the Back of a Cocktail Napkin'' (Princeton University Press, 2008). A companion article on 31 March gives an [http://www.nytimes.com/interactive/2009/03/31/science/20090331-angier-quiz.html online quiz] based on the book.<br />
<br />
The book serves as the text for course at Princeton in Spring, 2009, &quot;Physics 309: Physics on the Back of an Envelope&quot;, which was offered by one of the book's co-authors, Professor Lawrence Weinstein. His [http://www.lions.odu.edu/~lweinste/courses/309s09.html course website]<br />
links to sample midterms and to similar courses at MIT and CalTech.<br />
<br />
Submitted by Bill Peterson<br />
<br />
==Measuring drivers' drunken-ness==<br />
[http://online.wsj.com/article/SB124459653821000673.html#articleTabs%3Darticle "Drunk Driver Data Don't Walk Straight Line Either"], by Carl Bialik (The Numbers Guy), The Wall Street Journal, June 10, 2009<br><br />
<br />
This article describes a disagreement between Mothers Against Drunk Driving and a liquor-industry-funded group, Century Council, about the blood alcohol level that would trigger a proposed penalty requiring convicted drunk drivers to install an ignition interlock to prevent them driving when their breath alcohol level is "too high."<br> <br />
<br />
Century Council has stated that it wants to limit the level to a minimum of 0.15 grams per deciliter of blood, based on 2007 government studies that show that 3 out of 5 drivers involved in alcohol-related fatal crashes had a BACof at least 0.15, in contrast to about 1 out of 5 with BACs of 0.01 to 0.08 and 1 out of 5 with BACs of 0.09 to 0.14.<br><br />
<br />
According the article's author, a Weststat statistician believes that "the same personality traits that lead to driving while highly intoxicated are probably tied to other risky behavior behind the wheel" and that <br />
<blockquote>these heavy drinkers are far more dangerous than other drunken drivers on the road. [He] compared the blood-alcohol levels of drivers killed in crashes with levels of drivers stopped for random roadside testing during peak drunken-driving hours. .... Compared with sober drivers, drivers at 0.15 or higher were about 400 times more likely to die in a crash. Drivers with levels between 0.10 and 0.14 were 50 times more likely than sober drivers to die in a crash.</blockquote> <br />
<br />
MADD prefers a minimum "high" that is the legal limit of 0.08. A 2002 study at Johns Hopkins University, based on interviews with surviving family members of over 800 victims of fatal crashes, found that 55% of dead drivers with BAC levels of 0.15 or higher, and 35% of those with BAC levels between 0.10 and 0.14, drank at least monthly, leading a study co-author to state, "We shouldn't simply be focusing on 'hard-core' drivers."<br> <br />
<br />
According to the article's author, "some researchers would prefer to see a lower limit, with penalties tied to the blood-alcohol level, like with speeding penalties. .... Complicating matters, people's alcohol-metabolism varies, as does the relationship between their breath alcohol ... and their blood alcohol."<br> <br />
A blogger wrote, "I recall several years ago, a drunk was let go free because he was able to prove the variability in the gage [sic]."<br><br />
See [http://blogs.wsj.com/numbersguy/the-number-all-drivers-should-know-721/ "The Numbers All Drivers Should Know"] for more information on this topic from The Numbers Guy.<br><br />
Submitted by Margaret Cibes<br><br />
<br />
==Variables lurk in Wal-Mart study==<br />
[http://www.forbes.com/forbes/2009/0608/024-opinions-retail-health-on-my-mind.html "Wal-Mart's Weight Effect"], by Art Carden, Forbes Magazine, June 8, 2009<br><br />
<br />
This story reports preliminary findings from a University of NC-Greensboro study of big retail stores and obesity. The author of the article is a co-author of the study.<br />
<blockquote>In [the] first round of statistical analysis we found that greater consumer access to a Wal-Mart ... store was associated with lower body-mass indexes and a lower probability of being obese. ... [T]he correlation holds up under a variety of different circumstances, with a clear relationship between warehouse clubs and better eating habits emerging over time. Further, ... Wal-Mart's effect on weight is largest for women, the poor, African-Americans and people who live in urban areas. .... [W]hile we found a statistically significant effect on body mass index, the effect is very, very small.</blockquote><br />
<br />
[http://rate.forbes.com/comments/CommentServlet?op=cpage&sourcename=story&StoryURI=forbes/2009/0608/024-opinions-retail-health-on-my-mind.html&com=68666 Bloggers comment.]<br><br />
<br />
One blogger suggests that the observed effect of big retail stores on obesity may be a result of the fact that shoppers who purchase fresh fruits and vegetables at stores like Costco have to eat lots of these healthy foods in shorter periods of time because the packages are very large and the contents are perishable.<br><br />
<br />
A second blogger writes, "I notice that people who live within a 2-3 mile radius of my local Wal-Mart are better educated, have better access to health care (... a hospital), have more parks in close proximity, join more adult softball teams, and probably go to the dentist more often.<br />
.... This is a correlation [that] has to do with where Wal-Mart locates stores."<br><br />
<br />
A third blogger suggests an "exercise effect" due to long walks through large parking lots for large retail stores.<br><br />
<br />
Submitted by Margaret Cibes<br><br />
<br />
==A New Math War?==<br />
<br />
[http://chronicle.com/free/2009/06/19910n.htm?utm_source=at&utm_medium=en The Chronicle of Higher Education]<br />
June 12, 2009<br />
Jeffrey R. Young<br />
<br />
This article suggests that Wolfram's new [http://www.wolframalpha.com/ WolframAlpha] will create a war over whether their calculus students should be allowed to have WolframAlpha solve their homework. Of course their is nothing special about calculus because Alpha can also solve problems in other math courses, for example statistics. In addition to giving the answer to a problem but Alpha also tells how it found the solution. There is disagreement about whether they should allow the students to use Alpha, but it does not seem that it will lead to war as suggested by the title.<br />
<br />
Those who do not want to change their way of teaching will probably say that students cannot use Alpha while those who are willing to change their ways will figure out a way to take advantage of their students use Alpha. Or they can follow the advice of David Bressoud, president of the Mathematical Association of America who says:<br />
<br />
<blockquote>Most math instructors now realize that the end-all and be-all of math instruction is not to give students algorithmic facility, but it really is to understand the mathematical ideas and understand how to use them. </blockquote><br />
<br />
Submitted by Laurie Snell<br><br />
<br />
==Lead "paint"?==<br />
[http://www.nytimes.com/2009/05/28/fashion/28skin.html?_r=2 "A Simple Smooch or a Toxic Smack?"], by Abby Ellin, The New York Times, May 28, 2009<br><br />
<br />
This article discusses concerns about lead content in lipsticks. Some doctors and others believe that lipsticks contain high levels of lead, while the FDA believes that any lead content would merely be a harmless trace. Doctors also disagree about whether there is any "safe" level of lead.<br> <br />
<br />
In 2007 a study by a citizens' advocacy group found that "one-third of 33 lipsticks had lead in excess of 0.1 parts per million, the federal limit for candy."<br />
<blockquote>Among the worst offenders were L’Oreal Colour Riche “True Red” lipstick (with a lead content of 0.65 parts per million) and Cover Girl’s Incredifull Lipcolor “Maximum Red” (0.56 p.p.m.). Price had nothing to do with lead levels: less expensive brands, like a $1.99 tube of Wet and Wild Mega Colors “Cherry Blossom,” contained no lead, whereas a $24 tube of Dior Addict “Positive Red” [since discontinued] contained 0.21 p.p.m.</blockquote><br />
<br />
Manufacturers claim that their cosmetics are safe because they satisfy FDA requirements: manufacturers are only required to list "intended ingredients," not "unintended byproducts" of a manufacturing process, such as lead. Nevertheless, the advocacy group wants the FDA to release its data and to set a safety standard for lead in lipstick, not wait for a "peer-reviewed journal to publish its study of lead in lipstick."<br><br />
<br />
The editor of [http://www.stats.org Stats], at George Mason University's Center for Health and Risk Communication, says, "These things sound terribly scary, but there’s a massive disconnect between how toxicologists evaluate risks and how activist groups evaluate risk, and even then there are debates.” In a March survey of over 900 members of the Society of Toxicology, 66% disagreed that cosmetics are a "significant source of chemical health risk," while 26% agreed and 8% "didn't know."<br><br />
<br />
Submitted by Margaret Cibes<br><br />
<br />
==Swine flu pandemonium==<br />
[http://www.courant.com/health/hc-swine-flu-pandemic-0612.artjun12,0,3556431.story "Connecticut Records Its Second Swine Flu Death"], by Arielle Levin Becker, The Hartford Courant, June 12, 2009<br><br />
<br />
On June 11, a 6-year-old Connecticut boy died, and his death was "linked" to the H1N1 virus; it was the 2nd recorded Connecticut death attributed to swine flu. This was also the day that the World Health Organization declared swine flu a pandemic.<br><br />
<br />
<blockquote>The boy had underlying medical conditions and had not attended school this year, according to the state Department of Public Health. .... The first person who died, a Waterbury resident over 50 whose death was announced last week, also had underlying medical problems.</blockquote><br />
<br />
The state health commissioner stated that "this death underscores the seriousness of influenza and the devastating impact it can have." He also said that ordinary seasonal flu kills about 36,000 people a year in the U.S.<br> <br />
<br />
<blockquote>Worldwide, there have been nearly 30,000 confirmed cases of the H1N1 virus in 74 countries. Nearly half of the confirmed cases were reported in the U.S. .... So far, swine flu has caused 144 deaths worldwide, compared with ordinary flu, which kills up to 500,000 people a year. .... In Connecticut, there have been 637 confirmed cases of swine flu, though health officials say the number of cases is likely much higher.</blockquote> <br />
<br />
The World Health Organization director-general stated that "the overwhelming majority of patients experience mild symptoms and make a rapid and full recovery, often in the absence of any form of medical treatment." According to the article's author, "The pandemic designation refers to the virus's sustained geographic spread, not its severity."<br><br />
<br />
There is a 1 to 5 scale for measuring pandemics, depending upon "what portion of the population becomes ill and what portion of those with the illness die." The 1918 Spanish flu was a category 5 pandemic, in which "30 percent of the population became ill and 3 percent of those died." It is said to have caused 650,000 deaths in the U.S., and 20-40 million deaths worldwide. The 1968 pandemic was a category 2 pandemic, with 34,000 U.S. deaths ("similar to a typical seasonal flu") and 1 million worldwide deaths.<br><br />
<br />
Submitted by Margaret Cibes<br><br />
<br />
==Meteorite hits boy==<br />
[http://www.telegraph.co.uk/scienceandtechnology/science/space/5511619/14-year-old-hit-by-30000-mph-space-meteorite.html "14-year-old hit by 30,000 mph space meteorite"], The Telegraph, June 12, 2009<br><br />
<br />
Gerrit Blank survived a direct hit to his hand by a meteorite as it hurtled to Earth at "more than 30,000 miles per hour".<br><br />
<br />
<blockquote>A red hot, pea-sized piece of rock then hit his hand before bouncing off and causing a foot wide crater in the ground.<br />
<br />
The teenager survived the strike, '''the chances of which are just 1 in a million''' - but with a nasty three-inch long scar on his hand.</blockquote><br />
<br />
From [http://www.wired.com/images_blogs/wiredscience/2009/06/meteorite-nearmisses.jpg Wired magazine], some meteorite "near misses" in history:<br />
<br />
<center> http://www.wired.com/images_blogs/wiredscience/2009/06/meteorite-nearmisses.jpg </center><br />
<br />
Discussion<br><br />
<br />
1. How do you think the speed of 30,000 miles per hour was determined?<br> <br />
<br />
2. Is surviving being struck by a meteorite a "1 in a million" chance, or is this rather poetic license? What are the actual probabilities associated with being struck by a meteorite? What about surviving such a strike?<br><br />
<br />
Submitted by Gregory Kohs<br></div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=File:Meteorite_near_misses.jpg&diff=13294File:Meteorite near misses.jpg2009-06-16T15:20:02Z<p>Thekohser: Fix link</p>
<hr />
<div>From Wired magazine, web page: [http://www.wired.com/images_blogs/wiredscience/2009/06/meteorite-nearmisses.jpg link to image]. Fair use entitlement.</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=File:Meteorite_near_misses.jpg&diff=7721File:Meteorite near misses.jpg2009-06-16T15:19:33Z<p>Thekohser: From Wired magazine, web page: http://www.wired.com/images_blogs/wiredscience/2009/06/meteorite-nearmisses.jpg Fair use entitlement.</p>
<hr />
<div>From Wired magazine, web page: http://www.wired.com/images_blogs/wiredscience/2009/06/meteorite-nearmisses.jpg Fair use entitlement.</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=User_talk:Bill_Peterson&diff=13284User talk:Bill Peterson2009-03-31T14:09:25Z<p>Thekohser: Thank you!</p>
<hr />
<div>Bill, thanks for helping to copyedit the Issue 45 of Chance News. It was sort of my idea for Snell to issue a "pre-publication alert", so that we have a chance to get in there and tighten up the typography, grammar, links, etc. I'm glad that the idea didn't go unheeded. -- [[User:Thekohser|Thekohser]] 10:09, 31 Mar 2009 (EDT)</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_45&diff=10659Chance News 452009-03-25T15:26:04Z<p>Thekohser: Editorial fixes</p>
<hr />
<div>==Quotations==<br />
<blockquote>Science is not the arbiter of truth. All it can do is offer opinions about the answers to certain questions that we ask of nature. And it reserves the right to revise those opinions in the light of future discoveries.<br><br><br />
<br />
Even mathematics loses touch with any notion of truth once it steps into the real world. Last May, the director of the Max Planck Institute for Mathematics in Germany, warned that financial systems were operating in dangerous territory because traders were transferring their naive notions of the truth of mathematics on to the "black box" models used to predict and control trading. A few months later, we all found out just how dangerous that territory was.</blockquote><br />
<div align=right><br><br />
Michael Brooks</div><br><br />
[http://www.guardian.co.uk/commentisfree/2009/jan/24/science-cern-particle-collider The Guardian]<br> <br />
Saturday, 24 January, 2009<br><br />
<br />
Submitted by Laurie Snell<br><br />
<br />
==Forsooths==<br />
<br />
<center>College Kids and Monkeys About Equal on Math </center><br />
<br />
<div align="right">Robert Preidt <br> [http://health.msn.com/health-topics/articlepage.aspx?cp-documentid=100233038 MSN Health & Fitness] headline<br></div><br />
Submitted by Paul Alper<br />
-----<br />
The following Forsooth is from the March 2009 RSS NEWS:<br />
<br />
<blockquote>The other kind of variable is called a quantitative variable in which numbers are used to order or to represent increasing levels of that variable. The simplest example of a quantitative variable is a dichotomous variable such as sex or genre, where one category is seen as representing more of that quality than the other. For example, if females are coded as 1 and males as 2, then this variable may be seen as reflecting maleness in which the higher score indicates maleness. The next simplest example is a variable consisting of three categories such as social class, which may comprise the three categories of upper, middle and lower. Upper class may be coded as 1, middle as 2 and lower as 3, in which case lower values represent higher social statuses. These numbers may be treated as a ratio measure or scale. Someone who is coded as 1 is ranked twice as high as someone who is coded as 2 giving a ratio of 1 to 2.</blockquote><br />
<br />
<div align = "right">Advanced Quantitative Data Analysis<br><br />
<br />
Open University Press, 2003</div><br />
<br />
==Fixing a "failed" airplane?==<br />
<blockquote>The financial engineers are at it again.<br><br><br />
<br />
Critics may complain that these math wizards started the trouble in the first place by designing securities that couldn't withstand the market's turbulence. But they also may have the expertise to help fix the problem.<br><br><br />
<br />
"Airplanes fail, too," says Peter Cotton, founder of Julius Finance, a structured-finance firm in New York. "That doesn't mean you don't fix them."</blockquote><br />
<br />
<div align=right><br><br />
The [http://online.wsj.com/article/SB123534685897644327.html Wall Street Journal], February 23, 2009<br><br />
"Math Wizards Working On Spells to 'Cure'"<br><br />
Scott Patterson</div><br><br />
Submitted by Margaret Cibes<br />
<br />
==Intelligent dice?==<br />
<blockquote>March 4 [http://online.wsj.com/article/SB123612357581623583.html headline] = "Charts Suggest Dow Is Due For a Bounce"<br><br><br />
<br />
March 13 [http://online.wsj.com/article/SB123691682862416587.html headline] = "The Dangerous Game of Predicting When Stocks Have Bottomed Out: Good Luck, Because Market Doesn't Care About Your Call"<br><br><br />
<br />
<div align=right><br><br />
The Wall Street Journal 2009<br><br />
<div align=left><br><br />
Submitted by Margaret Cibes<br><br />
<br />
==Is an intelligent mutual fund manager worth the cost==<br />
<br />
[http://www.nytimes.com/2009/02/22/your-money/stocks-and-bonds/22stra.html The Index Funds Win Again] Mark Hulbert, The New York Times, February 21, 2009.<br />
<br />
We pay mutual fund managers a substantial fee to invest our money intelligently. Hedge fund managers ask for even larger fees. Do we get value in return for this money? An alternative, the index fund, simply tries to match the return of the overall market and does not try to pick stocks that are expected to perform better than average. You could, for example, buy one share of every stock represented in the Standard and Poor's 500. Such a fund would never do better than average, but it would cost a lot less to administer because you would not be paying for a team of researchers to comb through the news reports to try to identify individual stocks or broad market sectors that are expected to perform better than average.<br />
<br />
Most index funds do not purchase all 500 stocks in the S&P 500 (or all 3,000 stocks in the Russell 3000) but rather select a representative sample.<br />
<br />
The data seems to indicate that actively managed funds do not do much better than index funds, especially after expenses are accounted for. A new study by Mark Kritzman appears to confirm this belief.<br />
<br />
Expenses associated with a mutual fund are surprisingly difficult to calculate. <br />
<br />
<blockquote>"The bite taken out by taxes, for example, depends on the specific combination of positive years and losing ones, as well as the order in which they occur. That combination and order also affect the performance fees charged by hedge funds."</blockquote><br />
<br />
The average actively managed fund and the average hedge fund did outperform the index fund before expenses, but<br />
<br />
<blockquote>"For both the actively managed fund and the hedge fund, those expenses more than ate up the large amounts — 3.5 and 9 percentage points a year, respectively — by which they beat the index fund before expenses."</blockquote><br />
<br />
Of course, no one expects to select an average fund. If you pick a very well managed fund, is it likely to pay off?<br />
<br />
<blockquote>"Mr. Kritzman calculates that just to break even with the index fund, net of all expenses, the actively managed fund would have to outperform it by an average of 4.3 percentage points a year on a pre-expense basis. For the hedge fund, that margin would have to be 10 points a year. The chances of finding such funds are next to zero, said Russell Wermers, a finance professor at the University of Maryland. Consider the 452 domestic equity mutual funds in the Morningstar database that existed for the 20 years through January of this year. Morningstar reports that just 13 of those funds beat the Standard & Poor’s 500-stock index by at least four percentage points a year, on average, over that period. That’s less than 3 out of every 100 funds."</blockquote><br />
<br />
What makes it worse is that these 3% of the funds were only obvious in hindsight. Picking a fund that will perform well in the future is a very difficult task. Keep in mind the warning that appears in most investment literature "past performance is no guarantee of future results".<br />
<br />
The first popular criticism of the expenses associated with actively managed funds was a book by Burton Malkiel, "A Random Walk Down Main Street." Dr. Malkiel argues for the efficient market hypothesis, which states that the current prices of a stock represents all that is currently known about a stock, and that any changes represent a random walk.<br />
<br />
The [http://en.wikipedia.org/wiki/Index_fund Wikipedia article on index funds] offers a historical perspective on index funds. John Bogle started the first index fund in 1975. It was widely derided at the time.<br />
<br />
<blockquote>"At the time, it was heavily derided by competitors as being 'un-American' and the fund itself was seen as 'Bogle's folly'. Fidelity Investments Chairman Edward Johnson was quoted as saying that he '[couldn't] believe that the great mass of investors are going to be satisfied with receiving just average returns'."</blockquote><br />
<br />
The fund, now called the Vanguard 500 Index Fund, is the most popular mutual fund available to the general public.<br />
<br />
Submitted by Steve Simon<br />
<br />
===Questions===<br />
<br />
1. How would you pick a representative sample from the Standard and Poor's 500 or any other stock index?<br />
<br />
2. What statistical principle is behind the saying that past performance does not guarantee future results?<br />
<br />
3. Is it possible for a "great mass of investors" to experience above average returns?<br />
<br />
==Autism Statistics Lesson==<br />
<br />
Autism is a devastating disease. Recent attempts to pinpoint a cause have been recently in the news in the United States: [http://www.nytimes.com/2009/02/13/health/13vaccine.html?scp=1&sq=donald%20g.%20mcneil%20autism&st=cse New York Times article] by Donald G. McNeil, Jr. and [http://www.nytimes.com/2009/02/13/opinion/13fri2.html?scp=1&sq=editorial%20vaccines&st=cse a follow-on New York Times editorial]. The focus of these articles is on law suits regarding the measles, mumps and rubella (MMR) vaccine “or its combination with thimerosal, a mercury-based preservative that was used in most childhood vaccines until 2001,” as a cause of autism. After “5000 pages of testimony from experts and 939 medical articles,” judges concluded the plaintiffs failed to prove their assertions. One judge “ruled that the evidence was ‘overwhelmingly contrary’ to their argument.” <br />
<br />
Coincidentally, in England autism was also in the news in February, [http://briandeer.com/mmr/lancet-summary.htm here] and [http://briandeer.com/mmr-lancet.htm here]. In this instance, the story begins back in 1998 [http://download.videohelp.com/vitualis/downloads/Wakefield_%20LancetVolume%20351(9103)February28-1998.pdf The Lancet, February, 1998] and ignores thimerosal but introduces a problem additional to autism due to the MMR vaccine, Crohn’s disease (inflammatory bowel disease). The Lancet article had an extraordinary impact on the general public in England as the following graph indicates:<br />
<br />
<br />
http://www.dartmouth.edu/~chance/forwiki/autism.gif<br />
<br />
<br />
MMR inoculation rates fall off sharply after the Lancet article and start to rise in 2004 because of a (London) Sunday Times investigation which revealed serious deficiencies in the Lancet study. These deficiencies often fall under the rubric of “follow the money,” a concept not given enough attention when discussing what constitutes statistical literacy.<br />
<br />
The phrase, “follow the money,” is often thought to have originated in the book, All the President’s Men. According to [http://newsmine.org/content.php?ol=deceptions/deep-throat/follow-the-money-phrase-written-by-princess-bride-author.txt Frank Rich] the book never uses that phrase. It is however, from the film of the same name. Obviously, the pharmaceutical industry has a vested financial interest in vaccines and [http://www.huffingtonpost.com/deirdre-imus/on-vaccinations-consider_b_165347.html?show_comment_id=20767201 Deirdre Imus] is suspicious of any “big pharma” vaccine and any doctor who sides with it. The main author of the Lancet article, Andrew Wakefield, unbeknownst to the twelve other authors of the Lancet study, had been paid “about $780,000 plus expenses, for his role in backing the generic case against MMR.” Further, he had a patent on “a single vaccine against measles—a potential competitor to MMR” which he claimed would cure “both inflammatory bowel disease and autism.” As cited by [http://www.washingtonpost.com/wp-dyn/articles/A41450-2004Jul10.htm Glenn Frankel] ten of the twelve other authors in 2004 issued a “Retraction of an interpretation” because “no causal link was established between MMR vaccine and autism.” Wakefield has since moved to the U.S. and according to a supporter of Wakefield, “The United States, with its privatized health care system and entrepreneurial spirit is much more fertile ground than Britain for a medical pioneer like Wakefield.” According to [http://www.timesonline.co.uk/tol/life_and_style/health/article5683671.ece Brian Deer] official figures showed that 1,348 confirmed cases of measles in England and Wales were reported last year [2008], compared with 56 in 1998. Two children have died of the disease.”<br />
<br />
===Discussion===<br />
<br />
1. If the medical profession overwhelmingly believes the MMR vaccine to be safe, why are parents of autistic children actively seeking litigation? That is, what element of emotional guilt might there be?<br />
<br />
2. Although there were 13 authors of the Lancet article, there were only twelve children in the study. A multiplicity of authors is a common phenomenon in medical journals. Why is this so?<br />
<br />
3. The Lancet article claims that in eight of the twelve children, “the average exposure to first behavioral symptoms was 6.3 days (range 1-14)” after receiving the MMR vaccine. An earlier version of the paper, not unearthed until 2005, puts the average at 14 days with the maximum time as 56 days. Further, it was later revealed that there was “no trace of measles virus [or mumps and rubella viruses] in any of the children.” Subsequent investigation indicated that instead of Crohn’s disease, the children were suffering from a benign condition, severe constipation. Moreover, the children were not randomly referred by general practitioners but were recruited from a lawyer “who had been attempting to raise a speculative lawsuit.” In 2007, Wakefield abandoned a libel claim, and agreed to pay costs, “estimated at about £500,000.” Assuming all of this is factually correct, explain why some parents still view Wakefield as a hero.<br />
<br />
Submitted by Paul Alper<br />
<br />
==BBC Six-Part Primer on Understanding Statistics in the News==<br />
On the [http://www.amstat.org/news/archive.cfm News & Announcements] page from the American Statistical Association we read:<br />
<br />
Last year, the BBC ran a [http://www.amstat.org/news/blastland_bbcprimer.cfm six-part primer] by Michael Blastland on understanding statistics in the news. Blastland takes on the media’s handling of surveys/polls, counting, percentages, averages, causation and doubt. “Wouldn't it be good,” Blastland said, “to have the mental agility to separate the wheat from the chaff?” He then proceeds, in six weekly articles, to point out the obvious vs. the correct ways to interpret the data.<br />
<br />
Follow the links below to the BBC web site to read Michael Blastland’s six-part primer on understanding statistics in<br />
the news.<br />
<br />
[http://news.bbc.co.uk/1/hi/magazine/7542886.stm Surveys:]<br />
<br />
[http://news.bbc.co.uk/2/hi/uk_news/magazine/7554022.stm Counting: ]<br />
<br />
[http://news.bbc.co.uk/2/hi/uk_news/magazine/7568929.stm Percentages:]<br />
<br />
[http://news.bbc.co.uk/2/hi/uk_news/magazine/7581120.stm Averages:]<br />
<br />
[http://news.bbc.co.uk/2/hi/uk_news/magazine/7592579.stm Causation:]<br />
<br />
[http://news.bbc.co.uk/2/hi/uk_news/magazine/7605118.stm Doubt:]<br />
<br />
Michael Blastland and Andrew Dilnot have written a book, ''What Are the Odds a Handy, Quotable Statistic Is Lying? Better Than Even'' which was recently [http://www.nytimes.com/2009/02/03/books/03gewen.html reviewed] in the New York Times by Barry Gewen. The review begins with: <br />
<br />
<blockquote>It’s hard to resist a book that tells you that most people have more than the average number of feet. Or that researchers have found that Republicans enjoy sex more than Democrats do. Michael Blastland and Andrew Dilnot delight in bringing such facts to our attention — and then in explaining them away.</blockquote><br />
<br />
===Discussion===<br />
<br />
How do you think the authors "explained away" these two examples?<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Most basketball statistics are worthless==<br />
<br />
[http://www.nytimes.com/2009/02/15/magazine/15Battier-t.html The No-Stats All-Star] Michael Lewis, The New York Times, February 15, 2009.<br />
<br />
One of the best NBA basketball stars may have some of the worst statistics. Shane Battier of the Houston Rockets specializes in defense.<br />
<br />
<blockquote>Battier has routinely guarded the league’s most dangerous offensive players — LeBron James, Chris Paul, Paul Pierce — and has usually managed to render them, if not entirely ineffectual, then a lot less effectual than they normally are. He has done it so quietly that no one really notices what exactly he is up to.</blockquote><br />
<br />
Shane Battier does not do any of the things that are likely to gain him public recognition.<br />
<br />
<blockquote>His conventional statistics are unremarkable: he doesn’t score many points, snag many rebounds, block many shots, steal many balls or dish out many assists. On top of that, it is easy to see what he can never do: what points he scores tend to come from jump shots taken immediately after receiving a pass. “That’s the telltale sign of someone who can’t ramp up his offense,” Morey says. “Because you can guard that shot with one player. And until you can’t guard someone with one player, you really haven’t created an offensive situation. Shane can’t create an offensive situation. He needs to be open.” For fun, Morey shows me video of a few rare instances of Battier scoring when he hasn’t exactly been open. Some large percentage of them came when he was being guarded by an inferior defender — whereupon Battier backed him down and tossed in a left jump-hook. “This is probably, to be honest with you, his only offensive move,” Morey says. “But look, see how he pump fakes.” Battier indeed pump faked, several times, before he shot over a defender. “He does that because he’s worried about his shot being blocked.” Battier’s weaknesses arise from physical limitations. Or, as Morey puts it, “He can’t dribble, he’s slow and hasn’t got much body control.”</blockquote><br />
<br />
But he does help in the statistic that counts the most, wins.<br />
<br />
<blockquote>The Grizzlies went from 23-59 in Battier’s rookie year to 50-32 in his third year, when they made the NBA playoffs, as they did in each of his final three seasons with the team. Before the 2006-07 season, Battier was traded to the Houston Rockets, who had just finished 34-48. In his first season with the Rockets, they finished 52-30, and then, last year, went 55-27 — including one stretch of 22 wins in a row.</blockquote><br />
<br />
The person who recognized Shane Battier's influence is Daryl Morey.<br />
<br />
<blockquote>In 2005, the Houston Rockets’ owner, Leslie Alexander, decided to hire new management for his losing team and went looking specifically for someone willing to rethink the game. “We now have all this data,” Alexander told me. “And we have computers that can analyze that data. And I wanted to use that data in a progressive way. When I hired Daryl, it was because I wanted somebody that was doing more than just looking at players in the normal way. I mean, I’m not even sure we’re playing the game the right way.”</blockquote><br />
<br />
The first step in using statistics in basketball is recognizing which statistics are helpful and which ones are deceptive. <br />
<br />
<blockquote>[T]he big challenge on any basketball court is to measure the right things. The five players on any basketball team are far more than the sum of their parts; the Rockets devote a lot of energy to untangling subtle interactions among the team’s elements. To get at this they need something that basketball hasn’t historically supplied: meaningful statistics. For most of its history basketball has measured not so much what is important as what is easy to measure — points, rebounds, assists, steals, blocked shots — and these measurements have warped perceptions of the game. (“Someone created the box score,” Morey says, “and he should be shot.”) How many points a player scores, for example, is no true indication of how much he has helped his team. Another example: if you want to know a player’s value as a rebounder, you need to know not whether he got a rebound but the likelihood of the team getting the rebound when a missed shot enters that player’s zone.</blockquote><br />
<br />
There is a wealth of discussion about selfish statistics, statistics that a player amasses to his own benefit, but to the detriment of the team. Shane Battier is effective because he is a very selfless player -- he makes choices that help his team rather than choices that pad his own statistics.<br />
<br />
Submitted by Steve Simon<br />
<br />
==A rare event==<br />
<br />
Roger Woodard, Statistician at North Carolina University, wrote to [http://www.lawrence.edu/fast/jordanj/isostat.html Isostat] :<br />
<br />
<blockquote> It is rare that we see an article in the news that is willing to give you its data. There is an article in "The Big Money" that has a very nice graphic relating the ratings by critics and box office take of big blockbuster movies. It presents scatterplots, discusses correlations and regression lines. It is an article that should hold general interest for many students.<br><br><br />
<br />
But more importantly this article allows you to download the data the<br />
authors used. And more amazingly, this article's last lines are "E-mail us, too, if you have any insights, questions, or complaints about the data or methodology. We're eager for as many people to play with these data as possible."<br />
<br />
You can get the article (and link to the data) <br />
<br />
[http://www.thebigmoney.com/articles/impressions/2009/03/05/we-know-watchmen- here]</blockquote><br />
<br />
Submitted by Laurie Snell<br />
<br />
==Videos on the economic crisis==<br />
<br />
In Chance News 43 we discussed an [http://www.nytimes.com/2009/01/04/magazine/04risk-t.html article] in the New York Times entitled "Risk Mismanagement". This article introduced Nassim Nicholas Taleb, author of ''Fooled by Randomness'' and the ''Black Swan'' and gave his explanation for the world's current financial crisis. The article did not mention the well known mathematician Benoit Mandelbrot whose work on fractals provides the mathematics for Taleb's theories. Mandelbrot is the author of the book ''The (Mis) Behavior of Markets (A Fractal View of Financial Turbulence)''. They are good friends and you can listen [http://openanthropology.vodspot.tv/watch/1879134-taleb-and-mandelbrot-on-the-economic-crisis here] to an interview they gave on the economic crisis. You can find other interesting interviews on the state of the economic crisis at the same place, including one by Noam Chomsky.<br />
<br />
==Serious Medical Fraud==<br />
<br />
In [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_22#I_wasn.27t_making_up_data.2C_I_was_imputing.21 an earlier Chance News wiki] can be found a detailed treatment of the scientific fraud perpetrated by Eric Poehlman of the University of Vermont. In [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_22#Predecessors_of_Poehlman that same issue of Chance News] there is a discussion of Poehlman predecessors who, it is claimed, were even more egregious producers of fraudulent data. But now we have another contender for the title, Scott S. Reuben of Tufts University and Baystate Medical Center.<br />
<br />
According to [http://www.anesthesiologynews.com/index.asp?ses=ogst&section_id=3&show=dept&article_id=12634 Anesthesiology News], <br />
<br />
Scott S. Reuben, MD, of Baystate Medical Center in Springfield, Mass., a pioneer in the area of multimodal analgesia, is said to have fabricated his results in at least 21, and perhaps many more, articles dating back to 1996. The confirmed articles were published in Anesthesiology, Anesthesia and Analgesia, the Journal of Clinical Anesthesia and other titles, which have retracted the papers or will soon do so, according to people familiar with the scandal. The journals stressed that Dr. Reuben's co-authors on those papers have not been accused of wrongdoing.<br />
<br />
In addition to allegedly falsifying data, Dr. Reuben seems to have committed publishing forgery. Evan Ekman, MD, an orthopedic surgeon in Columbia, S.C., said his name appeared as a co-author on at least two of the retracted papers, despite his having had no hand in the manuscripts. "My names were forgeries on the documents," Dr. Ekman told Anesthesiology News.<br />
<br />
The reason Reuben’s fraud is so serious is because<br />
<br />
1. Dr. Reuben has been an extremely active and visible figure in multimodal analgesia, particularly as an advocate for its use in minimally invasive orthopedic and spine procedures. His research has provided support for several mainstays of current anesthetic practice, such as the use of nonsteroidal anti-inflammatory drugs [NSAIDs] and neuropathic agents instead of opioids and preemptive analgesia. Dr. Reuben has also published and presented data suggesting that multimodal analgesia can significantly improve long-term outcomes for patients.<br />
<br />
2. In a recent [http://www.sciam.com/article.cfm?id=a-medical-madoff-anesthestesiologist-faked-data Scientific American article], which dubbed Scott "A Medical Madoff", we read: "We are talking about millions of patients worldwide, where postoperative pain management has been affected by the research findings of Dr. Reuben," says Steven Shafer, editor in chief of the journal Anesthesia & Analgesia, which published 10 of Reuben's fraudulent papers.<br />
<br />
Paul White, another editor at the journal, estimates that Reuben's studies led to the sale of billions of dollars worth of the potentially dangerous drugs known as COX2 inhibitors, Pfizer's Celebrex (celecoxib) and Merck's Vioxx (rofecoxib), for applications whose therapeutic benefits are now in question. Reuben was a member of Pfizer's speaker's bureau and received five independent research grants from the company. The editors do not believe patients were significantly harmed by the short-term use of these COX2 inhibitors for pain management but they say it's possible the therapy may have prolonged recovery periods. <br />
<br />
From [http://online.wsj.com/article/SB123672510903888207.html the Wall Street Journal]: <br />
<br />
The [Baystate Medical Center] hospital has asked the medical journals to retract the 21 studies, some of which reported favorable results from the use of painkillers like Pfizer Inc.'s Bextra and Merc & Co.'s Vioxx -- both since withdrawn -- as well as Pfizer's Celebrex and Lyrica. Dr. Reuben's research work also claimed positive findings for Wyeth's antidepressant Effexor XR as a pain killer. And he wrote to the Food and Drug Administration, urging the agency not to restrict the use of many of the painkillers he studied, citing his own data on their safety and effectiveness.<br />
<br />
Discussion<br />
<br />
1. The Anesthesiology News article provided this intriguing statistical insight: "Interestingly, when you look at Scott's output over the last 15 years, he never had a negative study," said one colleague, who spoke on the condition of anonymity. "In fact, they were all very robust results--where others had failed to show much difference. I just don't understand why anyone would do this or how anyone could pull this off for so long." How is this similar to the Madoff scandal?<br />
<br />
2. The fraud was uncovered in a strange way. During a routine audit at Baystate, two of Reuben’s abstracts had not been approved by the hospital’s institutional review board (IRB), causing a possible breach of ethics because, whenever patients are involved, IRB approval is required. It turned out that IRB approval was not needed “because the data were fabricated” according to Dr. Jenson, chief academic officer of Baystate. “He told Anesthesiology News that simply put, Dr. Reuben had concocted the data—and in many cases the patients themselves—out of vapor.” Use Google to see the similarity and differences between this and that of the famous Cyril Burt fraud involving identical twins putatively separated at birth. <br />
<br />
3. From [http://www.sciam.com/article.cfm?id=a-medical-madoff-anesthestesiologist-faked-data Scientific American]: In hindsight, Anesthesia & Analgesia editors Shafer and White admit that it should have been a "red flag" that Reuben's studies were consistently favorable to the drugs he studied. White, who has also received drug company educational grants, says that such funding comes with "subtle pressure" to give the companies the results they want. For now, at least, neither the drug companies nor Reuben's co-authors are officially sharing in the blame, but that's expected to change. "There's a lot of responsibility to pass around," White says, "It's all being focused on Scott Reuben, but the reality is there are many other responsible parties." What might be the subtle and not-so-subtle pressures of the sponsoring agencies and the institution itself?<br />
<br />
4. Reuben’s journal articles are full of very small p-values and clinically significant effect sizes indicating that NSAIDs are safe and effective for pain medication after surgery. Indeed, his journal articles have the exquisite appearance of how proper comparisons should be presented. Below is a figure taken from an article supposedly co-authored with Ekman. What does this indicate about the peer review process? <br />
<br />
<center>http://www.dartmouth.edu/~chance/forwiki/cn451.gif </center><br />
<center> <span style="color:#ff0000"> This article has been retracted </span></center><br />
<br />
Fig. 1 Illustration depicting the dose of morphine at each postoperative time-interval. The placebo group is represented by the straight line, and the celecoxib group is represented by the dashed line. The boxes represent the twenty-fifth to seventy-fifth percentiles, the horizontal lines represent the means, and the extended I-bars represent the fifth to ninety-fifth percentiles. Outliers, as shown by the solid circles, represent values that are >1.5 times the box length. The mean morphine dose at the first six postoperative time-intervals was significantly increased in the placebo group compared with the celecoxib group, as indicated by the double asterisks (p < 0.0001). The mean morphine dose at twenty-four hours was significantly increased in the placebo group compared with the celecoxib group, as indicated by the single asterisk (p < 0.003).<br />
<br />
Submitted by Paul Alper<br />
<br />
==Losing at the half, winning in the end==<br />
<br />
The popular New York Times column [http://freakonomics.blogs.nytimes.com/2009/03/17/when-losing-leads-to-winning/ Freakonomics] had an interesting piece on basketball recently. Even more interesting is the academic article cited there: [http://qbox.wharton.upenn.edu/documents/mktg/research/Losing_and_Winning.pdf When Losing Leads to Winning], by Jonah Berger and Devin Pope of the University of Pennsylvania. The following graph illustrates their main point:<br />
<br />
http://www.dartmouth.edu/~chance/forwiki/cn45.gif<br />
<br />
That is, based on about 6500 NCAA basketball games, although being behind at the half is usually more likely to produce a loss, a one-point deficit at the half has a (surprisingly) higher probability of a win (51.3%) than being tied at the half (50%). They postulate that losing can lead to winning and cite a concept of “loss aversion.”<br />
<br />
Discussion<br />
<br />
1. Why is the above graph symmetrical about zero (game tied at the half)?<br />
<br />
2. The following graph is not in the article itself but is courtesy of the authors:<br />
<br />
<center>http://www.dartmouth.edu/~chance/forwiki/CN45-2.gif</center><br />
<br />
This graph, unlike the previous one, is not symmetrical about zero. However, regarding “When Losing Leads to Winning,” how is this graph similar to the previous one regarding the concept of “loss aversion”? What new ingredient makes it different?<br />
<br />
3. The following punch line is from the New York Times: “It’s an intriguing finding: being behind by a little yields the greatest possible effort. And while these researchers measure these effects on the basketball court, or on pounding keyboards [other investigations done by Berger and Pope in their article], their implications for the rest of our lives are even more intriguing. Want your workers to work harder? Tell them that they are running a close second in the race for promotion.” Google Niccolò Machiavelli and see what he wrote on the subject of inspiring underlings to perform better.<br />
<br />
Submitted by Paul Alper</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=10770Chance News 312009-01-25T00:59:34Z<p>Thekohser: /* The Unbreakable Wikipedia? */ Replacing broken link</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 are non-white, with Inter fielding, 19,<br> Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
* This issue has been covered in the BBC radio 4 series [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7078555.stm More or Less.]<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state. However, the problem is clearly growing:<br />
<br />
<center>http://www.mywikibiz.com/images/2/21/DamagedViews.jpg</center><br />
<br />
It is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our assessment is that the Minnesota study would have accepted a passage like this as completely "undamaged".<br />
<br />
From the "[http://www.mywikibiz.com/Worst_of_Wikipedia/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
===Potential bias in the study===<br />
'''1. From the study:'''<br />
<blockquote><br />
''We assume that one serving of an article by a Wikipedia server is a reasonable proxy for one view of that article by a user.''</blockquote><br />
:'''Critique:'''<br />
Humans don't read the entire article every time they load one in their browser. [http://www.poynterextra.org/eyetrack2004/main.htm Studies have shown] that readers of web pages tend to focus most of their priority on the top-left portion of the page. Therefore, this study is giving equal weight to words that appear at the bottom of an article, even though there is disproportionate reader emphasis on the first paragraph or two of any Wikipedia article.<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to bury his content in the middle or toward the end of Wikipedia articles, though fewer people being served the article would actually read his content.<br />
<br><br><br />
'''2. From the study:'''<br />
<blockquote><br />
''A tempting proxy for article views is article edits. However, we found essentially no correlation between views and edits in the request logs.''</blockquote><br />
:'''Critique:'''<br />
Why was there "essentially no correlation"? Popular, often-viewed pages on Wikipedia (examples include the articles about [http://en.wikipedia.org/wiki/Wiki wiki], [http://en.wikipedia.org/wiki/Chris_Benoit Chris Benoit], [http://en.wikipedia.org/wiki/Ann_Coulter Ann Coulter], [http://en.wikipedia.org/wiki/List_of_sex_positions List of sex positions], and [http://en.wikipedia.org/wiki/Jeff_Hardy Jeff Hardy]) are frequently semi-protected (only registered users with 4 days of experience may modify the article) or fully-protected (only administrators may access the edit feature). In fact, the above articles have all appeared in Wikipedia's "10 most popular articles of the month" list, and all remain protected from free editing. Therefore, a very powerful ''inverse'' relationship between views and edits would exist for [http://tools.wikimedia.de/~leon/stats/wikicharts/index.php?ns=articles&limit=100&month=08%2F2006&wiki=enwiki Wikipedia's most popular pages]; which probably topples the otherwise intuitive correlation between article views and article edits. Are the study's authors cognizant of this?<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add his content to contentious, popular articles, just before they are "locked down" from further editing. A Wikipedia administrator would have the capacity to make substantial edits to an article just before himself locking down (or asking an admin colleague to lock down) the very same article.<br />
<br><br><br />
'''3. From the study:'''<br />
<blockquote><br />
''...if a contribution is viewed many times without being changed or deleted, it is likely to be <s>a</s> valuable.''</blockquote><br />
:'''Critique:'''<br />
Or, equally likely, the contribution is not being read critically, or even read at all. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add content that is wordy, boring, and dense. Prose that intimidates or sedates the reader would be so bland as to encourage skimming (rather than editing!), every time it is viewed.<br />
<br><br><br />
'''4. From the study:'''<br />
<blockquote><br />
''Our software does not track persistent words if text is "cut-and-pasted" from one article to another. If an editor moves a block of text from one article to another, PWVs after the move will be credited to the moving editor, not to the original editors.''</blockquote><br />
:'''Critique:'''<br />
Large credit goes, then, to "text movers" rather than "text creators". People who move a lot of text around will typically be busy-body administrators, rather than the careful scholars who painstakingly wrote the material in the first place. It is a known fact that the busiest administrators do a lot of "tidying" of major articles which lack any trace of their own content. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to become an administrator, then move a bunch of well-written content from article to article, which is frequently done among articles like "History of Tuscany" to "History of Italy" to "History of the Mediterranean" to "History of Europe" to the God-awful "History of western Eurasia".<br />
<br><br><br />
'''5. From the study:'''<br />
<blockquote><br />
''We exclude anonymous editors from some analyses, because IPs are not stable: multiple edits by the same human might be recorded under different IPs, and multiple humans can share an IP.''</blockquote><br />
:'''Critique:'''<br />
The same could be said for registered user accounts, which can be used from different IP addresses, by different people who know the password. It is a fact that some contributors to this very Chance News wiki are known to share registered Wikipedia user accounts. Regardless, the study itself found that anonymous IPs made 9 trillion edits out of a total of 34 trillion. Why would the study therefore exclude over 26% of the sample? This would have the effect of elevating the relative strength of contributions by a finite number of registered accounts, which is exactly what the study concludes. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to set up an account that he then shares with other like-minded individuals, so that more round-the-clock editing is possible, thereby building credibility in the community as a "dedicated Wikipedian". <br />
<br><br><br />
'''6. From the study:'''<br />
<blockquote><br />
''Reverts take two forms: '''identity revert''', where the post-revert revision is identical to a previous version, and '''effective revert''', where the effects of prior edits are removed (perhaps only partially), but the new text is not identical to any prior revision. ...In this paper, we consider only identity reverts.''</blockquote><br />
:'''Critique:'''<br />
Identity reverts, since they are a "button" tool that may seem intimidating to an average user, are probably more likely to be used by administrators, not scholars. Therefore, this study again gives extra strength to the actions of mop-wielding admins, rather than earnest shapers of Wikipedia. <br />
:'''Gaming the system:'''<br />
To count for more in this study, you wouldn't ever want to work to "improve" fixable recent content in Wikipedia. Rather, revert it, then re-write it in your own words.<br />
<br><br><br />
'''7. From the study:'''<br />
<blockquote><br />
''We believe it is reasonable to assume that essentially all damage is repaired within 15 revisions.''</blockquote><br />
:'''Critique:'''<br />
This may be so, but Figure 8 in the report also shows that 20% of the "Damaged-Loose" content incidents in Wikipedia are viewed by at least 30 people before they get fixed. Ten percent of such mistakes are viewed by well over 100 people before repaired. <br />
:'''Gaming the system:'''<br />
Learning to write mistaken or vandalistic prose in such a way that many, many people read it without "noticing" that it is wrong would be a way to further extend the time and views until detection. The libelous content written about [http://en.wikipedia.org/wiki/Seigenthaler_controversy John Seigenthaler, Sr.] and about [http://en.wikipedia.org/wiki/Fuzzy_Zoeller#Controversies Fuzzy Zoeller] went unnoticed for a number of weeks or months without causing any alarm. An effective way to make unsuspecting readers believe a lie in Wikipedia is to show a reference citation next to the false content. The reference need not even link to a source making the same claim you are making.<br />
<br />
==Rudy wrong on cancer survival chances==<br />
The [http://blog.washingtonpost.com/fact-checker/2007/10/rudy_miscalculates_cancer_surv.html ''Washington Post Fact Checker'', Oct. 30, 2007]<br><br />
Michael Dobbs<br />
<br />
This Blog describes its goal as follows:<br />
<br />
<blockquote>Our goal is to shed as much light as possible on controversial claims and counter-claims involving important national issues and the records of the various presidential candidates.</blockquote><br />
<br />
Here they discuss Giuliani’s New Hampshire radio advertisement, October 29, 2007.<br />
<br />
<blockquote>I had prostate cancer, five, six years ago. My chances of surviving prostate cancer and thank God I was cured of it, in the United States, 82 percent. My chances of surviving prostate cancer in England, only 44 percent under socialized medicine.</blockquote><br />
<br />
It is not clear what is being compared here. It is probably meant to be the survival rate. This is defined by the National Cancer Institution as: <br />
<br />
<blockquote>The percentage of people in a study or treatment group who are alive for a given period of time after diagnosis. This is commonly expressed as 5-year survival.</blockquote><br />
<br />
The Giuliani campaign reports that these percentages came from an article in [http://www.city-journal.org/html/17_3_canadian_healthcare.html ''City Journal''], a publication of the Manhattan Institute, a conservative research organization. This article, ''The Ugly Truth About Canadian Health Care'', was written by Dr. Lavid Gratzer, a senior fellow at the Manhattan Institute and an adviser for the Giuliani campaign. While the article did not say where the numbers came from, Dr. Gratzer has now explained that they came from a Commonwealth Fund article<br />
''Multination Comparisons of Health Systems Data, 2000'' by Gerard F. Anderson and Peter S. Hussey of Johns Hopkins University. Specifically they came from this graphic in the Commenwealth Fund article:<br />
<br />
<center> http://www.dartmouth.edu/~chance/forwiki/prostate.jpg</center><br />
<br />
The Commonweath Fund provided a [http://www.commonwealthfund.org/newsroom/newsroom_show.htm?doc_id=568333 a Statement] in repsonse to Giuliani’s advertisement. They say:<br />
<br />
<blockquote>The incidence rates simply report the number of men diagnosed with prostate cancer in a given year. Prostate cancer mortality rates report the number of men who died of the disease in a given year. Neither speaks to length of survival, and that figure can not be calculated using the others. </blockquote> <br />
<br />
But Dr. Gratzer defends Guiliani's ad in an article "On cancer survival rates, Rudy’s right and his critics are wrong" ''City Journal'', 31 October 2007. Here we read: <br />
<br />
<blockquote>Let me be very clear about why the Giuliani campaign is correct: the percentage of people diagnosed with prostate cancer who die from it is much higher in Britain than in the United States. The Organization for Economic Co-operation and Development reports on both the incidence of prostate cancer in member nations and the number of resultant deaths. According to OECD data published in 2000, 49 Britons per 100,000 were diagnosed with prostate cancer, and 28 per 100,000 died of it. This means that 57 percent of Britons diagnosed with prostate cancer died of it; and, consequently, that just 43 percent survived.</blockquote><br />
<br />
Finally, from the Washington Post Blog we read:<br />
<br />
<blockquote>UPDATE: Maria Comella, deputy communications manager for the Giuliani campaign, sent us the following e-mail explaining the mayor's mistake without quite acknowledging it: <blockquote>Mayor Giuliani is an avid reader of ''City Journal'' and found the passage in the Gratzer article himself. He cited the statistics at a campaign stop, and the campaign used a recording from that appearance in the radio ad. The citation is an article in a highy respected intellectual journal written by an expert at a highly respected think tank which the mayor read because he is an intellectually engaged human being.</blockquote><br />
<br />
===Discussion===<br />
<br />
(1) Do you agree with the Commonwealth Fund statement?<br />
<br />
(2) Do you agree with Gretzer's explanation?<br />
<br />
(3) Others say that the difference is caused by the fact that the United States screens for Prostate Cancer earlier than England does so of course the survival rate will be longer. Is this relevant to this controversy?<br />
<br />
==More or less==<br />
[http://www.ft.com/cms/s/0/52e30ae6-9191-11dc-9590-0000779fd2ac.html Lunch with the FT: Andrew Dilnot,] by Tim Harford, The Financial Times, 16 Nov 2007.<br />
<br />
Chance readers may be interested in a BBC Radio 4 series called [http://news.bbc.co.uk/1/hi/programmes/more_or_less/ <em>More or less</em>,] which is about numbers in the news.<br />
(The original presenter [http://en.wikipedia.org/wiki/Andrew_Dilnot Andrew Dilnot] recently <br />
[http://www.ft.com/cms/s/0/52e30ae6-9191-11dc-9590-0000779fd2ac.html stepped down]<br />
to be replaced by [http://www.timharford.com/ Tim Hartford,] <br />
who writes the 'Dear Economist' column for the Financial Times.)<br />
<br />
The website for the programme gives a hint at the topics covered:<br />
* [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7101633.stm predicting bird flu]<br />
* [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7090524.stm measuring happiness]<br />
* [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7078555.stm migrant figures that do not add up] (covered in a Chance news article in this issue)<br />
* [http://open2.net/sciencetechnologynature/maths/coincidence.html The dangers of spotting patterns in random things]<br />
<br />
Dilnot says that in the radio show<br />
<blockquote><br />
We are trying to show people how they can interpret the numbers that are thrown at them.<br />
</blockquote><br />
He advises people to ask simple questions, such as: <em>Is that a big number?</em><br />
In the interview by Harford, Dilnot claims that <br />
the worst social statistic of all time was that <br />
<em>the number of children killed in the United States has doubled every year since 1953</em>.<br />
<br />
One simple trick is to try to humanize statistics, Dilnot claims:<br />
<blockquote><br />
Faced with a question such as: <em>how many petrol (gasoline in the US) stations are there in the UK?</em>, ask yourself how many petrol stations there are in your town, and how many people. It’s the first step towards grasping a sensible answer to the bigger question.<br />
</blockquote><br />
<br />
Dilnot has written that just about the only question that can’t be partially answered with reference to personal experience is: <em>how many penguins are there in Antarctica?</em> due to the difficulties of a credible penguin census.<br />
<br />
===Questions===<br />
* What is wrong with the claim that <em>the number of children killed in the United States has doubled every year since 1953</em>? <br />
* What is your estimate of how many penguins there are in Antarctica? What bounds do you wish to put around your estimate?<br />
<br />
===Further reading===<br />
* More or Less can be heard on Mondays on BBC Radio 4 at 16:30 BST and is presented by Tim Harford.<br />
** More or Less is a permanent part of the schedule with two series annually, one in the summer, one in winter. <br />
** Here is a link to [http://www.bbc.co.uk/radio/aod/mainframe.shtml?http://www.bbc.co.uk/radio/aod/radio4_aod.shtml?radio4/moreorless the most recent version].<br />
** Since January 2005, it has been produced in association with [http://www.open2.net/moreorless/ the Open University,] who provide links to related webpages, such as: [http://open2.net/sciencetechnologynature/maths/statisticsmedia.html Statistics and the media] and [http://open2.net/sciencetechnologynature/maths/statistics.html Guide to statistics.]<br />
* [http://plus.maths.org/issue45/features/tiger/index.html The Tiger That Isn’t,] Andrew Dilnot's recent book covering similar topics to the radio show.<br />
** Plus Magazine offer a [http://plus.maths.org/issue45/reviews/book2/ review of this book.]<br />
* [http://www.amazon.co.uk/Undercover-Economist-Tim-Harford/dp/0316732931 The Undercover Economist,] a recent book by the new presenter, Tim Harford.<br />
<br />
Submitted by John Gavin.<br />
<br />
==Name-Letter-Effect==<br />
An article in Psychological Science, Volume 18 Issue 12 Page 1106-1112, December 2007 by Nelson and Simmons has received much attention in the lay press, including, Sports Illustrated, Newsweek and USA Today. From the abstract of the article: "we found that people like their names enough to unconsciously pursue consciously avoided outcomes that resemble their names." In other words, as USA Today put it in its headline, "My name made me do it." Put another way, instead of astrology with its alignment of the stars at birth causing your success or failure, it is the name given to you that predicts behavior.<br />
<br />
The article discusses five studies. The "it" in the first study refers to Major League Baseball players who have an initial "K"-the symbol for recording strikeouts--strike out more often, 18.8%, than players with other initials, 17.2%. This study looked at 6397 players who had at least 100 at bats. A hypothesis test was performed and the authors state that "t(6395) = 3.08," yielding a p-value of ".002." However, using the same database, a [http://sabermetricresearch.blogspot.com Blogger] found otherwise; in particular, for 1960s to 2000s: Ks 14.5%, non-Ks 14.2%. This blogger concludes with, "So the big question remains: why did the authors get such a high strikeout rate difference?"<br />
<br />
Here is why: Nelson and Simmons did not do the customary hypothesis test of difference in proportions but instead did a hypothesis test of the difference in means. That is, a batter's strikeout to at bat ratio was not weighted by the number of at bats.<br />
<br />
The "it" in the second study refers to MBA academic performance at an unnamed institution. Looking at about 15,000 students, "As predicted, students whose names begin with a C or D earned lower GPAs than students whose names begin with A or B, F(4, 14348) = 4.55" yielding a p-value of ".001." The effect size is teeny and somehow, those whose initials are E through Z actually have the highest average GPAs.<br />
<br />
===Discussion===<br />
<br />
1. Baseball is full of slang. Two common terms for striking out are "fanning" and "whiffing." Obtain [http://www.baseball-databank.org/ the data set] and do a test for F or W to see what p-value ensues.<br />
<br />
2. The figure below is Fig. 1 in the original paper where the GPAs of A, B, C, D, and Other are displayed. Why is the graph misleading?<br />
<br />
<center> http://www.dartmouth.edu/~chance/forwiki/Figure1.jpg</center><br />
<br />
<center>Fig. 1. Results of Study 2: grade point average <br><br />
as a function of the student's initial. Error bars in...</center><br />
<br />
3. The "it" in a third study looks at 492,458 lawyers at 170 law schools. The dependent variable is law-school quality which varies from Tier 1 (best), Tier 2, Tier 3, Tier 4 (worst). The independent variable is "the proportion of lawyers with initials A and B (relative to lawyers with initials C and D)." The regression result was a slope of -.17 yielding a p-value of .036. The authors conclude, "It seems that people with names like Adlai and Bill tend to go to better law schools that do those with names like Chester and Dwight." Comment on the qualitative nature of the dependent variable and how regression might be affected. Comment on Bill.<br />
<br />
4. The Newsweek writer notes that "the GPA gap is tiny-3.34 versus 3.36." She then claims, "But there is a saying in science that if you discover a way to levitate objects with your thoughts by one millimeter, you don't focus on the millimeter-the size of the effect-but on the fact that something happened at all." Defend and criticize her statement.<br />
<br />
Submitted by Paul Alper</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_40&diff=13280Chance News 402008-10-13T02:40:00Z<p>Thekohser: /* Wikipedia vandalism to U.S. Senators */ Discussion welcomed</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote>When I worked at the Labor Party think tank, trying to talk about these issues [oppression of Muslim women], people always accused me of failing to back up my arguments with data. But hard numbers were completely unavailable. When I tried to find out about honor killings, for instance-how many girls were killed every year in Holland by their fathers and brothers because of their precious family honor-civil servants at the Ministry of Justice would tell me, "We don't register murders based on that category of motivation. It would stigmatize one group in society." The Dutch government registered the number of drug-related killings and traffic accidents every year, but not the number of honor killings, because no Dutch official wanted to recognize that this kind of murder happened on a regular basis.</blockquote><br />
<br />
<div align=right>Aayan Hirsi Ali<br><b>Infidel</b>, Free Press: New York NY<br> pages 295-296.</div><br />
<br />
Suggested by Steve Simon<br />
<br />
==Forsooth==<br />
<br />
From the [http://www.independent.co.uk/ Independent], 13/09/08:<br />
<blockquote>Last week, a formatting error led to us inadvertently suggesting that there was a one in 1,019 chance of the world ending before this edition. That should have read, er, one in 10<SUP>19</SUP> – rather less likely. Sorry. Feel free to remove the crash helmet.</blockquote><br />
<br />
Suggested by Gareth Hagger-Johnson<br />
<br />
----<br />
From SEED Magazine (Sept/Oct 2008 issue pg 89)<br />
<br />
<blockquote>If you play golf, you could be adding five years to your life. A new study<br />
shows that the death rate for Scandanavian golfers is 40% lower than for<br />
those who don't golf. The reason may be simple: Golfers walk, spend time<br />
outdoors, and developing social relationships. The social interaction can<br />
be especially important for the older age groups. Researchers have not<br />
ruled out the possibility that golfers simply live healthy lives in<br />
general, but they believe that the game itself does have health benefits.</blockquote><br />
<br />
Submitted by William Montante<br />
<br />
----<br />
<br />
<blockquote> "We're off by a factor of a lot."--Tony Miller, founder of Carol.com a company that hoped to sell about 200 healthcare policies a month but after eight months sold but a total of 160.<br />
<div align="right">Minneapolis Star Tribune. <br><br />
September 28, 2008</div><br></blockquote><br />
<br />
Submitted by Paul Alper<br />
----<br />
<br />
The following Forsooths are from the October 2008 RRS<br />
<br />
<blockquote>If you do not have so many players, what can you do? There are 95 registered Brazilian players in the Championship League, 94 French players and 45 English players. When you have twice as few players as other countries it is difficult.<br />
<br />
<div align="right"> Dailey Telegraph'<br><br />
27 November 2007</div></blockquote><br />
----<br />
<blockquote>England have been drawn against their Euro 2008 nemeses Croatia for the 2010 World Cup South Africa qualifiers<br />
...It was almost inevitable that Sunday's World Cup draw would throw the two nations together again...<br />
----<br />
<div align="right"> BBC Neews Sport<br><br />
5 December 2007</div></blockquote><br />
----<br />
<blockquote>Michael Ballack's heart must have skipped a beat for a microsecond.<br />
<br />
<div align="right"> Sky Sports<br><br />
26 April 2008</div></blockquote><br />
<br />
==Discussion==<br />
<br />
Explain why each of these RSS Forsooths are Forsooths.<br />
<br />
== Understanding Uncertainty ==<br />
<br />
The website [http://understandinguncertainty.org/about Understanding Uncertainty] is maintained by [http://www.mrc-bsu.cam.ac.uk/BSUsite/AboutUs/People/davids.xml David Spiegelhalter ] at Cambridge University. The website provides modules that analize uncertainty issues written by Spiegelhalter with help by others. So far they have provided the following modules:<br />
<br />
Coincidences<br><br />
National Lottery<br><br />
Premier League<br><br />
What is Probability?<br><br />
Risk in the media<br><br />
How long are you going to live?<br><br />
<br />
When they are completed, a more detailed discussion appears in [http://plus.maths.org/issue48/index.html Cambridge Math Journal Plus]<br />
<br />
The most recent issue of Plus includes the article [http://plus.maths.org/issue48/risk/index.htmlUnderstanding uncertainty: How long will you live?] by Mike Pearson and David Spiegelhalter. As in previous modules this module includes elegent animations provided by Mike Pearson. <br />
<br />
The data for this module consists of UK interim life tables 1982-2006.<br />
<br />
In the first animation we see the age and the % Hazard = Chance of death before next birthday and the age of the individual lives evolve through time.<br />
<br />
In the second animation we can find the chance of death before our next birthday. We put in 83 and found that there is a 9.1% chance that we will die before our next birthday, <br />
<br />
From the third animation we find that our life expectance is 89. However in the fourth animation we find that, since we are:<br />
<br />
Non smoker<br> <br />
5 day a week Fruit/Veg<br> <br />
Moderate Alcohol<br> <br />
Physically Active<br><br />
<br />
our Expected Age of death is 91<br />
<br />
We think you will enjoy this and other of their modules.<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Are bad models to blame?==<br />
<br />
[http://bits.blogs.nytimes.com/2008/09/18/how-wall-streets-quants-lied-to-their-computers How Wall Street Lied to Its Computers], Saul Hansell, New York Times Technology Blog, September 18, 2008.<br />
<br />
There is a lot of speculation on why major Wall Street firms are reeling from piles of bad debt. These firms hire some of the best and brightest financial experts. These experts are supposed to manage risk to avoid this sort of problem.<br />
<br />
There is some speculation that this is just bad luck.<br />
<br />
<blockquote>the level of financial distress is “the equivalent of the 100-year flood,” in the words of Leslie Rahl, the president of Capital Market Risk Advisors, a consulting firm.</blockquote><br />
<br />
But that's only part of the story. Some of the blame comes from bad models.<br />
<br />
<blockquote>"There was a willful designing of the systems to measure the risks in a certain way that would not necessarily pick up all the right risks," said Gregg Berman, the co-head of the risk-management group at RiskMetrics, a software company spun out of JPMorgan.</blockquote><br />
<br />
Why would anyone deliberately use a bad model?<br />
<br />
<blockquote>Lying to your risk-management computer is like lying to your doctor. You just aren’t going to get the help you really need.</blockquote><br />
<br />
This may be a case of the fox being in charge of the hen house. Higher risk investments are attractive during good times because they offer greater levels of return than low risk investments. They have to offer greater returns, because they wouldn't be able to attract investors otherwise. But these greater returns will disappear if you have to hold back a large financial reserve to cover the downside risk. So there is a great temptation to pretend that high risk investments are really not high risk.<br />
<br />
How were these models flawed? One thought is that they used the wrong time horizon.<br />
<br />
<blockquote>One way they did this, Mr. Berman said, was to make sure the computer models looked at several years of trading history instead of just the last few months. The most important models calculate a measure known as Value at Risk — the amount of money you might lose in the worst plausible situation. They try to figure out what that worst case is by looking at how volatile markets have been in the past.</blockquote><br />
<br />
<blockquote>But since the markets were placid for several years (as mortgage bankers busily lent money to anyone with a pulse), the computers were slow to say that risk had increased as defaults started to rise.</blockquote><br />
<br />
<blockquote>It was like a weather forecaster in Houston last weekend talking about the onset of Hurricane Ike by giving the average wind speed for the previous month. </blockquote><br />
<br />
Another problem is that many new investments are far more complex than in the past.<br />
<br />
<blockquote>"New products, by definition, carry more risk,” [Ms. Rahl] said. The models should penalize investments that are complex, hard to understand and infrequently traded, she said. They didn’t.</blockquote><br />
<br />
Submitted by Steve Simon<br />
<br />
===Questions===<br />
<br />
1. This is just one of many examples of someone being pressured to produce results that skew the numbers in favor of a pre-ordained conclusion. What other examples are there?<br />
<br />
2. What protections need to be put into place to encourage the use of more accurate models?<br />
<br />
==Going for 2 points==<br />
<br />
The New York Times<br><br />
September 21, 2008<br><br> <br />
To the Sports Editor:<br />
<br />
Re ''[http://query.nytimes.com/gst/fullpage.html?res=9C02EFDA113AF935A2575AC0A96E9C8B63&partner=rssnyt&emc=rssIn Denver, a Rare Display of the Go-for-It Mentality],'' Sept. 16: Judy Battista's analysis of Mike Shanahan's decision to go for a late 2-point conversion in Denver's game against San Diego is statistically unsound. The relevant outcome is winning the game, not a successful conversion.<br />
<br />
If the probability of a point after succeeding is 0.99 and the probability of a 2-point conversion succeeding (for the Broncos) is 0.536, the probability of winning in extra time is 0.5 and the probability of another score in regular time is small, then the probability of winning with a 2-point attempt is 0.536. and the probability of winning with a P.A.T (Point After Touchdown). is 0.99 times 0.5, or 0.495. So the odds favor the 2-point attempt, not the P.A.T. Home-field advantage and other factors may change these probabilities, but the fact remains that the 2-point try is hardly a reckless gamble in this situation.<br />
<br />
<div align="right">Rod Little <br><br />
Ann Arbor, Mich</div><br><br />
<br />
===Discussion===<br />
<br />
(1) What do you think of Little's analysis?<br />
<br />
(2) Do you think that any of the probabilities Little mentions are known to three decimal points?<br />
<br />
Submitted by Laurie Snell<br />
<br />
==A chance to get rich==<br />
<br />
The recent wild swings of the stock market suggest a chance to get rich. This reminds me of one of my favorite Chance News articles that appeared in Chance News 5.08.<br />
<br />
Seen From a Rut, the Lottery Is Essential<br><br />
The New York Times<br><br />
July 16, 1996<br />
<br />
To the Editor:<br />
<br />
<blockquote>Your July 14 Week in Review article on lottery advertising repeats stereotypes about lottery players' being poor and uneducated and swept up into a gambling addiction. No doubt many are. But Gov. George E. Pataki's statement that "it has always bothered me to hold up the prospect of instant riches" could also be recast as, "I want to take away the only prospect poor people have of getting out of their rut."<br><br><br />
<br />
Before lotteries, other options existed for people to improve their lives, and the barriers were not so high. Graduate education today is expensive; many professions require training as well as licensing, and investing in stocks requires substantial equity. Most people are not so brilliant that they can start an Apple computer company in their garages. So, playing the lottery becomes a good investment when no alternative is better.<br><br><br />
<br />
Lottery players know that the odds are stacked against them, but they don't have to spend a lot of money. Quite a few win regularly. Many who play Lotto or Take 5 use wheeling systems, which, contrary to statements by lottery officials, do increase the chances of winning. I know; I play Lotto and I've won everything except the jackpot, and I win several times a year.<br><br><br />
<br />
Yes, I have lost more than I've won. But in the tedious world I inhabit along with so many other New Yorkers, I've bought a fantasy. If I ever win the jackpot, I'll wave to you from Sutton Place.</blockquote><br />
<br />
JOHN P. RASH New York, July 14, 1996<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Wikipedia vandalism to U.S. Senators==<br />
<br />
A recent [http://digg.com/politics/McCain_raped_wife_Obama_a_nudist_and_Hillary_has_a_penis methodical study] of Wikipedia's one hundred articles about the 100 U.S. Senators reveals that, on average, any one of these articles is in a state of mild vandalism to egregious defamation for about 1.63 hours per day. The study took data from the 4th quarter, 2007.<br />
<br />
In all, the median duration of a damaged edit was 6 minutes, but the mean duration was 1,440 minutes (exactly 24 hours). These 100 articles were viewed approximately 12.8 million times in the fourth quarter of 2007. Over 378,000 of those views could be considered "damaged", yielding a 2.96% rate of damaged views. There were about 13.2 million article-minutes during the quarter, and over 901,000 of those article-minutes were in a damaged state -- 6.80%.<br />
<br />
http://www.mywikibiz.com/images/8/8c/Vandal_study_screenshot.jpg<br />
<br />
<br><br />
<br />
Note that the study elected not to include certain types of common vandalism, such as "page blanking". The study also limited the bounds of vandals' entries to the duration of the calendar quarter, even if the vandalism pre-dated the October 1 entry point, or persisted beyond the December 31 exit point. So, conceivably, the "problem" of such vandalism is actually worse than reported in the summary above.<br />
<br />
The entire quarter's worth of data is available within [http://spreadsheets.google.com/pub?key=psAWteTSyixEB98YcV-5VEw a Google spreadsheet], where the [http://www.gregorykohs.com study's organizer] makes his private contact information available and welcomes discussion.<br />
<br />
===Discussion===<br />
<br />
(1) Were most of the vandalized edits made by anonymous IP addresses or by "registered" users of Wikipedia? Why does Wikipedia allow anonymous IP addresses to modify articles about named living persons?<br />
<br />
(2) Which of the 626 reported edits was most damaging to the subject of the article? Is it worse to have something highly libelous persist for a few minutes and a handful of readers, or something mildly hurtful persist for a few weeks and hundreds of readers?<br />
<br />
(3) What constitutes an "attractive nuisance"? What online entities were intended to be protected by Section 230 of the Communications Decency Act? Is Wikipedia merely an "interactive computer service" and therefore entitled to immunity from process that might otherwise be leveled at a print publisher?<br />
<br />
(4) Was this survey's methodology flawed in substantial ways? How so?<br />
<br />
''Submitted by Gregory Kohs''<br />
<br />
==PBS' Palin Poll==<br />
<br />
Readers of Chance News who wish to see how ineffective statistics education still is in the United States are directed [http://www.pbs.org/now/polls/poll-435.html here] where people are asked to vote on the following:<br />
<br />
<blockquote>Do you think Sarah Palin is qualified to serve as Vice President of the United States?"</blockquote><br />
<br />
No matter how often it is pointed out that voluntary surveys are more or less worthless, PBS, in hopes of increasing revenue via publicity, is pandering to the statistically illiterate in order to generate numbers which are entirely meaningless. <br />
<br />
This behavior is totally shameless. PBS tacitly admits [http://www.pbs.org/now/palin-poll.html here] that this voluntary poll is stupid and will be manipulated by the fierce partisans, but presses on with the farce, nevertheless. <br />
<br />
Readers of Chance News, the ones in the trenches who teach statistics, might wish to go [http://www.pbs.org/now/php/quotes.php?quote_date=2008-09-23 here] to add to the many critical comments about the poll.<br />
<br />
===Discussion===<br />
<br />
A friend of mine who teaches business strategy at Temple accuses statisticians of reveling in moral superiority because they refuse to participate in this enterprise and thus, let the statistically illiterate triumph. <br />
<br />
(1) Would a poll of this strategy of non-participation restricted to statisticians be meaningful? <br />
<br />
(2) Would a poll of this strategy of non-participation open to everyone be meaningful?<br />
<br />
Submitted by Paul Alper</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_40&diff=6059Chance News 402008-10-09T17:41:01Z<p>Thekohser: /* Wikipedia vandalism to U.S. Senators */ Adding image</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote>When I worked at the Labor Party think tank, trying to talk about these issues [oppression of Muslim women], people always accused me of failing to back up my arguments with data. But hard numbers were completely unavailable. When I tried to find out about honor killings, for instance-how many girls were killed every year in Holland by their fathers and brothers because of their precious family honor-civil servants at the Ministry of Justice would tell me, "We don't register murders based on that category of motivation. It would stigmatize one group in society." The Dutch government registered the number of drug-related killings and traffic accidents every year, but not the number of honor killings, because no Dutch official wanted to recognize that this kind of murder happened on a regular basis.</blockquote><br />
<br />
<div align=right>Aayan Hirsi Ali<br><b>Infidel</b>, Free Press: New York NY<br> pages 295-296.</div><br />
<br />
Suggested by Steve Simon<br />
<br />
==Forsooth==<br />
<br />
From the [http://www.independent.co.uk/ Independent], 13/09/08:<br />
<blockquote>Last week, a formatting error led to us inadvertently suggesting that there was a one in 1,019 chance of the world ending before this edition. That should have read, er, one in 10<SUP>19</SUP> – rather less likely. Sorry. Feel free to remove the crash helmet.</blockquote><br />
<br />
Suggested by Gareth Hagger-Johnson<br />
<br />
----<br />
From SEED Magazine (Sept/Oct 2008 issue pg 89)<br />
<br />
<blockquote>If you play golf, you could be adding five years to your life. A new study<br />
shows that the death rate for Scandanavian golfers is 40% lower than for<br />
those who don't golf. The reason may be simple: Golfers walk, spend time<br />
outdoors, and developing social relationships. The social interaction can<br />
be especially important for the older age groups. Researchers have not<br />
ruled out the possibility that golfers simply live healthy lives in<br />
general, but they believe that the game itself does have health benefits.</blockquote><br />
<br />
Submitted by William Montante<br />
<br />
----<br />
<blockquote> "We're off by a factor of a lot."--Tony Miller, founder of Carol.com a company that hoped to sell about 200 healthcare policies a month but after eight months sold but a total of 160.<br />
<div align="right">Minneapolis Star Tribune. <br><br />
September 28, 2008</div><br><br />
<br />
Submitted by Paul Alper<br />
----<br />
<br />
The following Forsooths are from the October 2008 RRS<br />
<br />
<blockquote>If you do not have so many players, what can you do? There are 95 registered Brazilian players in the Championship League, 94 French players and 45 English players. When you have twice as few players as other countries it is difficult.<br />
<br />
<div align="right"> Dailey Telegraph'<br><br />
27 November 2007</div></blockquote><br />
----<br />
<blockquote>England have been drawn against their Euro 2008 nemeses Croatia for the 2010 World Cup South Africa qualifiers<br />
...It was almost inevitable that Sunday's World Cup draw would throw the two nations together again...<br />
----<br />
<div align="right"> BBC Neews Sport<br><br />
5 December 2007</div></blockquote><br />
----<br />
<blockquote>Michael Ballack's heart must have skipped a beat for a microsecond.<br />
<br />
<div align="right"> Sky Sports<br><br />
26 April 2008</div></blockquote><br />
<br />
==Discussion==<br />
<br />
Explane why each of these RSS Forsooths are Forsooths.<br />
<br />
== Understanding Uncertainty ==<br />
<br />
The website [http://understandinguncertainty.org/about Understanding Uncertainty] is maintained by [http://www.mrc-bsu.cam.ac.uk/BSUsite/AboutUs/People/davids.xml David Spiegelhalter ] at Cambridge University. The website provides modules that analize uncertainty issues written by Spiegelhalter with help by others. So far they have provided the following modules:<br />
<br />
Coincidences<br><br />
National Lottery<br><br />
Premier League<br><br />
What is Probability?<br><br />
Risk in the media<br><br />
How long are you going to live?<br><br />
<br />
When they are completed, a more detailed discussion appears in [http://plus.maths.org/issue48/index.html Cambridge Math Journal Plus]<br />
<br />
The most recent issue of Plus includes the article [http://plus.maths.org/issue48/risk/index.htmlUnderstanding uncertainty: How long will you live?] by Mike Pearson and David Spiegelhalter. As in previous modules this module includes elegent animations provided by Mike Pearson. <br />
<br />
The data for this module consists of UK interim life tables 1982-2006.<br />
<br />
In the first animation we see the age and the % Hazard = Chance of death before next birthday and the age of the individual lives evolve through time.<br />
<br />
In the second animation we can find the chance of death before our next birthday. We put in 83 and found that there is a 9.1% chance that we will die before our next birthday, <br />
<br />
From the third animation we find that our life expectance is 89. However in the fourth animation we find that, since we are:<br />
<br />
Non smoker<br> <br />
5 day a week Fruit/Veg<br> <br />
Moderate Alcohol<br> <br />
Physically Active<br><br />
<br />
our Expected Age of death is 91<br />
<br />
We think you will enjoy this and other of their modules.<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Are bad models to blame?==<br />
<br />
[http://bits.blogs.nytimes.com/2008/09/18/how-wall-streets-quants-lied-to-their-computers How Wall Street Lied to Its Computers], Saul Hansell, New York Times Technology Blog, September 18, 2008.<br />
<br />
There is a lot of speculation on why major Wall Street firms are reeling from piles of bad debt. These firms hire some of the best and brightest financial experts. These experts are supposed to manage risk to avoid this sort of problem.<br />
<br />
There is some speculation that this is just bad luck.<br />
<br />
<blockquote>the level of financial distress is “the equivalent of the 100-year flood,” in the words of Leslie Rahl, the president of Capital Market Risk Advisors, a consulting firm.</blockquote><br />
<br />
But that's only part of the story. Some of the blame comes from bad models.<br />
<br />
<blockquote>"There was a willful designing of the systems to measure the risks in a certain way that would not necessarily pick up all the right risks," said Gregg Berman, the co-head of the risk-management group at RiskMetrics, a software company spun out of JPMorgan.</blockquote><br />
<br />
Why would anyone deliberately use a bad model?<br />
<br />
<blockquote>Lying to your risk-management computer is like lying to your doctor. You just aren’t going to get the help you really need.</blockquote><br />
<br />
This may be a case of the fox being in charge of the hen house. Higher risk investments are attractive during good times because they offer greater levels of return than low risk investments. They have to offer greater returns, because they wouldn't be able to attract investors otherwise. But these greater returns will disappear if you have to hold back a large financial reserve to cover the downside risk. So there is a great temptation to pretend that high risk investments are really not high risk.<br />
<br />
How were these models flawed? One thought is that they used the wrong time horizon.<br />
<br />
<blockquote>One way they did this, Mr. Berman said, was to make sure the computer models looked at several years of trading history instead of just the last few months. The most important models calculate a measure known as Value at Risk — the amount of money you might lose in the worst plausible situation. They try to figure out what that worst case is by looking at how volatile markets have been in the past.</blockquote><br />
<br />
<blockquote>But since the markets were placid for several years (as mortgage bankers busily lent money to anyone with a pulse), the computers were slow to say that risk had increased as defaults started to rise.</blockquote><br />
<br />
<blockquote>It was like a weather forecaster in Houston last weekend talking about the onset of Hurricane Ike by giving the average wind speed for the previous month. </blockquote><br />
<br />
Another problem is that many new investments are far more complex than in the past.<br />
<br />
<blockquote>"New products, by definition, carry more risk,” [Ms. Rahl] said. The models should penalize investments that are complex, hard to understand and infrequently traded, she said. They didn’t.</blockquote><br />
<br />
Submitted by Steve Simon<br />
<br />
===Questions===<br />
<br />
1. This is just one of many examples of someone being pressured to produce results that skew the numbers in favor of a pre-ordained conclusion. What other examples are there?<br />
<br />
2. What protections need to be put into place to encourage the use of more accurate models?<br />
<br />
==Going for 2 points==<br />
<br />
The New York Times<br><br />
September 21, 2008<br><br> <br />
To the Sports Editor:<br />
<br />
Re ''[http://query.nytimes.com/gst/fullpage.html?res=9C02EFDA113AF935A2575AC0A96E9C8B63&partner=rssnyt&emc=rssIn Denver, a Rare Display of the Go-for-It Mentality],'' Sept. 16: Judy Battista's analysis of Mike Shanahan's decision to go for a late 2-point conversion in Denver's game against San Diego is statistically unsound. The relevant outcome is winning the game, not a successful conversion.<br />
<br />
If the probability of a point after succeeding is 0.99 and the probability of a 2-point conversion succeeding (for the Broncos) is 0.536, the probability of winning in extra time is 0.5 and the probability of another score in regular time is small, then the probability of winning with a 2-point attempt is 0.536. and the probability of winning with a P.A.T (Point After Touchdown). is 0.99 times 0.5, or 0.495. So the odds favor the 2-point attempt, not the P.A.T. Home-field advantage and other factors may change these probabilities, but the fact remains that the 2-point try is hardly a reckless gamble in this situation.<br />
<br />
<div align="right">Rod Little <br><br />
Ann Arbor, Mich</div><br><br />
<br />
===Discussion===<br />
<br />
(1) What do you think of Little's analysis?<br />
<br />
(2) Do you think that any of the probabilities Little mentions are known to three decimal points?<br />
<br />
Submitted by Laurie Snell<br />
<br />
==A chance to get rich==<br />
<br />
The wild swings of the stock market provided a chance to get rich. It reminded me of one of my favorite articles reviewed by Chance News. <br />
<br />
Seen From a Rut, the Lottery Is Essential<br />
The New York Times<br />
July 16, 1996<br />
<br />
To the Editor:<br />
<br />
<blockquote>Your July 14 Week in Review article on lottery advertising repeats stereotypes about lottery players' being poor and uneducated and swept up into a gambling addiction. No doubt many are. But Gov. George E. Pataki's statement that "it has always bothered me to hold up the prospect of instant riches" could also be recast as, "I want to take away the only prospect poor people have of getting out of their rut."<br><br><br />
<br />
Before lotteries, other options existed for people to improve their lives, and the barriers were not so high. Graduate education today is expensive; many professions require training as well as licensing, and investing in stocks requires substantial equity. Most people are not so brilliant that they can start an Apple computer company in their garages. So, playing the lottery becomes a good investment when no alternative is better.<br><br><br />
<br />
Lottery players know that the odds are stacked against them, but they don't have to spend a lot of money. Quite a few win regularly. Many who play Lotto or Take 5 use wheeling systems, which, contrary to statements by lottery officials, do increase the chances of winning. I know; I play Lotto and I've won everything except the jackpot, and I win several times a year.<br><br><br />
<br />
Yes, I have lost more than I've won. But in the tedious world I inhabit along with so many other New Yorkers, I've bought a fantasy. If I ever win the jackpot, I'll wave to you from Sutton Place.</blockquote><br />
<br />
JOHN P. RASH New York, July 14, 1996<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Wikipedia vandalism to U.S. Senators==<br />
<br />
A recent [http://digg.com/politics/McCain_raped_wife_Obama_a_nudist_and_Hillary_has_a_penis methodical study] of Wikipedia's one hundred articles about the 100 U.S. Senators reveals that, on average, any one of these articles is in a state of mild vandalism to egregious defamation for about 1.63 hours per day. The study took data from the 4th quarter, 2007.<br />
<br />
In all, the median duration of a damaged edit was 6 minutes, but the mean duration was 1,440 minutes (exactly 24 hours). These 100 articles were viewed approximately 12.8 million times in the fourth quarter of 2007. Over 378,000 of those views could be considered "damaged", yielding a 2.96% rate of damaged views. There were about 13.2 million article-minutes during the quarter, and over 901,000 of those article-minutes were in a damaged state -- 6.80%.<br />
<br />
http://www.mywikibiz.com/images/8/8c/Vandal_study_screenshot.jpg<br />
<br />
<br><br />
<br />
Note that the study elected not to include certain types of common vandalism, such as "page blanking". The study also limited the bounds of vandals' entries to the duration of the calendar quarter, even if the vandalism pre-dated the October 1 entry point, or persisted beyond the December 31 exit point. So, conceivably, the "problem" of such vandalism is actually worse than reported in the summary above.<br />
<br />
The entire quarter's worth of data is available within [http://spreadsheets.google.com/pub?key=psAWteTSyixEB98YcV-5VEw a Google spreadsheet], where the [http://www.gregorykohs.com study's organizer] makes his private contact information available.<br />
<br />
===Discussion===<br />
<br />
(1) Were most of the vandalized edits made by anonymous IP addresses or by "registered" users of Wikipedia? Why does Wikipedia allow anonymous IP addresses to modify articles about named living persons?<br />
<br />
(2) Which of the 626 reported edits was most damaging to the subject of the article? Is it worse to have something highly libelous persist for a few minutes and a handful of readers, or something mildly hurtful persist for a few weeks and hundreds of readers?<br />
<br />
(3) What constitutes an "attractive nuisance"? What online entities were intended to be protected by Section 230 of the Communications Decency Act? Is Wikipedia merely an "interactive computer service" and therefore entitled to immunity from process that might otherwise be leveled at a print publisher?<br />
<br />
(4) Was this survey's methodology flawed in substantial ways? How so?<br />
<br />
''Submitted by Gregory Kohs''</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_40&diff=6058Chance News 402008-10-09T17:33:46Z<p>Thekohser: /* Wikipedia vandalism to U.S. Senators */ Updates to content</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote>When I worked at the Labor Party think tank, trying to talk about these issues [oppression of Muslim women], people always accused me of failing to back up my arguments with data. But hard numbers were completely unavailable. When I tried to find out about honor killings, for instance-how many girls were killed every year in Holland by their fathers and brothers because of their precious family honor-civil servants at the Ministry of Justice would tell me, "We don't register murders based on that category of motivation. It would stigmatize one group in society." The Dutch government registered the number of drug-related killings and traffic accidents every year, but not the number of honor killings, because no Dutch official wanted to recognize that this kind of murder happened on a regular basis.</blockquote><br />
<br />
<div align=right>Aayan Hirsi Ali<br><b>Infidel</b>, Free Press: New York NY<br> pages 295-296.</div><br />
<br />
Suggested by Steve Simon<br />
<br />
==Forsooth==<br />
<br />
From the [http://www.independent.co.uk/ Independent], 13/09/08:<br />
<blockquote>Last week, a formatting error led to us inadvertently suggesting that there was a one in 1,019 chance of the world ending before this edition. That should have read, er, one in 10<SUP>19</SUP> – rather less likely. Sorry. Feel free to remove the crash helmet.</blockquote><br />
<br />
Suggested by Gareth Hagger-Johnson<br />
<br />
----<br />
From SEED Magazine (Sept/Oct 2008 issue pg 89)<br />
<br />
<blockquote>If you play golf, you could be adding five years to your life. A new study<br />
shows that the death rate for Scandanavian golfers is 40% lower than for<br />
those who don't golf. The reason may be simple: Golfers walk, spend time<br />
outdoors, and developing social relationships. The social interaction can<br />
be especially important for the older age groups. Researchers have not<br />
ruled out the possibility that golfers simply live healthy lives in<br />
general, but they believe that the game itself does have health benefits.</blockquote><br />
<br />
Submitted by William Montante<br />
<br />
----<br />
<blockquote> "We're off by a factor of a lot."--Tony Miller, founder of Carol.com a company that hoped to sell about 200 healthcare policies a month but after eight months sold but a total of 160.<br />
<div align="right">Minneapolis Star Tribune. <br><br />
September 28, 2008</div><br><br />
<br />
Submitted by Paul Alper<br />
----<br />
<br />
The following Forsooths are from the October 2008 RRS<br />
<br />
<blockquote>If you do not have so many players, what can you do? There are 95 registered Brazilian players in the Championship League, 94 French players and 45 English players. When you have twice as few players as other countries it is difficult.<br />
<br />
<div align="right"> Dailey Telegraph'<br><br />
27 November 2007</div></blockquote><br />
----<br />
<blockquote>England have been drawn against their Euro 2008 nemeses Croatia for the 2010 World Cup South Africa qualifiers<br />
...It was almost inevitable that Sunday's World Cup draw would throw the two nations together again...<br />
----<br />
<div align="right"> BBC Neews Sport<br><br />
5 December 2007</div></blockquote><br />
----<br />
<blockquote>Michael Ballack's heart must have skipped a beat for a microsecond.<br />
<br />
<div align="right"> Sky Sports<br><br />
26 April 2008</div></blockquote><br />
<br />
==Discussion==<br />
<br />
Explane why each of these RSS Forsooths are Forsooths.<br />
<br />
== Understanding Uncertainty ==<br />
<br />
The website [http://understandinguncertainty.org/about Understanding Uncertainty] is maintained by [http://www.mrc-bsu.cam.ac.uk/BSUsite/AboutUs/People/davids.xml David Spiegelhalter ] at Cambridge University. The website provides modules that analize uncertainty issues written by Spiegelhalter with help by others. So far they have provided the following modules:<br />
<br />
Coincidences<br><br />
National Lottery<br><br />
Premier League<br><br />
What is Probability?<br><br />
Risk in the media<br><br />
How long are you going to live?<br><br />
<br />
When they are completed, a more detailed discussion appears in [http://plus.maths.org/issue48/index.html Cambridge Math Journal Plus]<br />
<br />
The most recent issue of Plus includes the article [http://plus.maths.org/issue48/risk/index.htmlUnderstanding uncertainty: How long will you live?] by Mike Pearson and David Spiegelhalter. As in previous modules this module includes elegent animations provided by Mike Pearson. <br />
<br />
The data for this module consists of UK interim life tables 1982-2006.<br />
<br />
In the first animation we see the age and the % Hazard = Chance of death before next birthday and the age of the individual lives evolve through time.<br />
<br />
In the second animation we can find the chance of death before our next birthday. We put in 83 and found that there is a 9.1% chance that we will die before our next birthday, <br />
<br />
From the third animation we find that our life expectance is 89. However in the fourth animation we find that, since we are:<br />
<br />
Non smoker<br> <br />
5 day a week Fruit/Veg<br> <br />
Moderate Alcohol<br> <br />
Physically Active<br><br />
<br />
our Expected Age of death is 91<br />
<br />
We think you will enjoy this and other of their modules.<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Are bad models to blame?==<br />
<br />
[http://bits.blogs.nytimes.com/2008/09/18/how-wall-streets-quants-lied-to-their-computers How Wall Street Lied to Its Computers], Saul Hansell, New York Times Technology Blog, September 18, 2008.<br />
<br />
There is a lot of speculation on why major Wall Street firms are reeling from piles of bad debt. These firms hire some of the best and brightest financial experts. These experts are supposed to manage risk to avoid this sort of problem.<br />
<br />
There is some speculation that this is just bad luck.<br />
<br />
<blockquote>the level of financial distress is “the equivalent of the 100-year flood,” in the words of Leslie Rahl, the president of Capital Market Risk Advisors, a consulting firm.</blockquote><br />
<br />
But that's only part of the story. Some of the blame comes from bad models.<br />
<br />
<blockquote>"There was a willful designing of the systems to measure the risks in a certain way that would not necessarily pick up all the right risks," said Gregg Berman, the co-head of the risk-management group at RiskMetrics, a software company spun out of JPMorgan.</blockquote><br />
<br />
Why would anyone deliberately use a bad model?<br />
<br />
<blockquote>Lying to your risk-management computer is like lying to your doctor. You just aren’t going to get the help you really need.</blockquote><br />
<br />
This may be a case of the fox being in charge of the hen house. Higher risk investments are attractive during good times because they offer greater levels of return than low risk investments. They have to offer greater returns, because they wouldn't be able to attract investors otherwise. But these greater returns will disappear if you have to hold back a large financial reserve to cover the downside risk. So there is a great temptation to pretend that high risk investments are really not high risk.<br />
<br />
How were these models flawed? One thought is that they used the wrong time horizon.<br />
<br />
<blockquote>One way they did this, Mr. Berman said, was to make sure the computer models looked at several years of trading history instead of just the last few months. The most important models calculate a measure known as Value at Risk — the amount of money you might lose in the worst plausible situation. They try to figure out what that worst case is by looking at how volatile markets have been in the past.</blockquote><br />
<br />
<blockquote>But since the markets were placid for several years (as mortgage bankers busily lent money to anyone with a pulse), the computers were slow to say that risk had increased as defaults started to rise.</blockquote><br />
<br />
<blockquote>It was like a weather forecaster in Houston last weekend talking about the onset of Hurricane Ike by giving the average wind speed for the previous month. </blockquote><br />
<br />
Another problem is that many new investments are far more complex than in the past.<br />
<br />
<blockquote>"New products, by definition, carry more risk,” [Ms. Rahl] said. The models should penalize investments that are complex, hard to understand and infrequently traded, she said. They didn’t.</blockquote><br />
<br />
Submitted by Steve Simon<br />
<br />
===Questions===<br />
<br />
1. This is just one of many examples of someone being pressured to produce results that skew the numbers in favor of a pre-ordained conclusion. What other examples are there?<br />
<br />
2. What protections need to be put into place to encourage the use of more accurate models?<br />
<br />
==Going for 2 points==<br />
<br />
The New York Times<br><br />
September 21, 2008<br><br> <br />
To the Sports Editor:<br />
<br />
Re ''[http://query.nytimes.com/gst/fullpage.html?res=9C02EFDA113AF935A2575AC0A96E9C8B63&partner=rssnyt&emc=rssIn Denver, a Rare Display of the Go-for-It Mentality],'' Sept. 16: Judy Battista's analysis of Mike Shanahan's decision to go for a late 2-point conversion in Denver's game against San Diego is statistically unsound. The relevant outcome is winning the game, not a successful conversion.<br />
<br />
If the probability of a point after succeeding is 0.99 and the probability of a 2-point conversion succeeding (for the Broncos) is 0.536, the probability of winning in extra time is 0.5 and the probability of another score in regular time is small, then the probability of winning with a 2-point attempt is 0.536. and the probability of winning with a P.A.T (Point After Touchdown). is 0.99 times 0.5, or 0.495. So the odds favor the 2-point attempt, not the P.A.T. Home-field advantage and other factors may change these probabilities, but the fact remains that the 2-point try is hardly a reckless gamble in this situation.<br />
<br />
<div align="right">Rod Little <br><br />
Ann Arbor, Mich</div><br><br />
<br />
===Discussion===<br />
<br />
(1) What do you think of Little's analysis?<br />
<br />
(2) Do you think that any of the probabilities Little mentions are known to three decimal points?<br />
<br />
Submitted by Laurie Snell<br />
<br />
==A chance to get rich==<br />
<br />
The wild swings of the stock market provided a chance to get rich. It reminded me of one of my favorite articles reviewed by Chance News. <br />
<br />
Seen From a Rut, the Lottery Is Essential<br />
The New York Times<br />
July 16, 1996<br />
<br />
To the Editor:<br />
<br />
<blockquote>Your July 14 Week in Review article on lottery advertising repeats stereotypes about lottery players' being poor and uneducated and swept up into a gambling addiction. No doubt many are. But Gov. George E. Pataki's statement that "it has always bothered me to hold up the prospect of instant riches" could also be recast as, "I want to take away the only prospect poor people have of getting out of their rut."<br><br><br />
<br />
Before lotteries, other options existed for people to improve their lives, and the barriers were not so high. Graduate education today is expensive; many professions require training as well as licensing, and investing in stocks requires substantial equity. Most people are not so brilliant that they can start an Apple computer company in their garages. So, playing the lottery becomes a good investment when no alternative is better.<br><br><br />
<br />
Lottery players know that the odds are stacked against them, but they don't have to spend a lot of money. Quite a few win regularly. Many who play Lotto or Take 5 use wheeling systems, which, contrary to statements by lottery officials, do increase the chances of winning. I know; I play Lotto and I've won everything except the jackpot, and I win several times a year.<br><br><br />
<br />
Yes, I have lost more than I've won. But in the tedious world I inhabit along with so many other New Yorkers, I've bought a fantasy. If I ever win the jackpot, I'll wave to you from Sutton Place.</blockquote><br />
<br />
JOHN P. RASH New York, July 14, 1996<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Wikipedia vandalism to U.S. Senators==<br />
<br />
A recent [http://digg.com/politics/McCain_raped_wife_Obama_a_nudist_and_Hillary_has_a_penis methodical study] of Wikipedia's one hundred articles about the 100 U.S. Senators reveals that, on average, any one of these articles is in a state of mild vandalism to egregious defamation for about 1.63 hours per day. The study took data from the 4th quarter, 2007.<br />
<br />
In all, the median duration of a damaged edit was 6 minutes, but the mean duration was 1,440 minutes (exactly 24 hours). These 100 articles were viewed approximately 12.8 million times in the fourth quarter of 2007. Over 378,000 of those views could be considered "damaged", yielding a 2.96% rate of damaged views. There were about 13.2 million article-minutes during the quarter, and over 901,000 of those article-minutes were in a damaged state -- 6.80%.<br />
<br />
Note that the study elected not to include certain types of common vandalism, such as "page blanking". The study also limited the bounds of vandals' entries to the duration of the calendar quarter, even if the vandalism pre-dated the October 1 entry point, or persisted beyond the December 31 exit point. So, conceivably, the "problem" of such vandalism is actually worse than reported in the summary above.<br />
<br />
The entire quarter's worth of data is available within [http://spreadsheets.google.com/pub?key=psAWteTSyixEB98YcV-5VEw a Google spreadsheet], where the [http://www.gregorykohs.com study's organizer] makes his private contact information available.<br />
<br />
===Discussion===<br />
<br />
(1) Were most of the vandalized edits made by anonymous IP addresses or by "registered" users of Wikipedia? Why does Wikipedia allow anonymous IP addresses to modify articles about named living persons?<br />
<br />
(2) Which of the 626 reported edits was most damaging to the subject of the article? Is it worse to have something highly libelous persist for a few minutes and a handful of readers, or something mildly hurtful persist for a few weeks and hundreds of readers?<br />
<br />
(3) What constitutes an "attractive nuisance"? What online entities were intended to be protected by Section 230 of the Communications Decency Act? Is Wikipedia merely an "interactive computer service" and therefore entitled to immunity from process that might otherwise be leveled at a print publisher?<br />
<br />
(4) Was this survey's methodology flawed in substantial ways? How so?<br />
<br />
Submitted by Gregory Kohs</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_40&diff=6057Chance News 402008-10-08T16:40:15Z<p>Thekohser: /* Wikipedia vandalism to U.S. Senators */ Link format</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote>When I worked at the Labor Party think tank, trying to talk about these issues [oppression of Muslim women], people always accused me of failing to back up my arguments with data. But hard numbers were completely unavailable. When I tried to find out about honor killings, for instance-how many girls were killed every year in Holland by their fathers and brothers because of their precious family honor-civil servants at the Ministry of Justice would tell me, "We don't register murders based on that category of motivation. It would stigmatize one group in society." The Dutch government registered the number of drug-related killings and traffic accidents every year, but not the number of honor killings, because no Dutch official wanted to recognize that this kind of murder happened on a regular basis.</blockquote><br />
<br />
<div align=right>Aayan Hirsi Ali<br><b>Infidel</b>, Free Press: New York NY<br> pages 295-296.</div><br />
<br />
Suggested by Steve Simon<br />
<br />
==Forsooth==<br />
<br />
From the [http://www.independent.co.uk/ Independent], 13/09/08:<br />
<blockquote>Last week, a formatting error led to us inadvertently suggesting that there was a one in 1,019 chance of the world ending before this edition. That should have read, er, one in 10<SUP>19</SUP> – rather less likely. Sorry. Feel free to remove the crash helmet.</blockquote><br />
<br />
Suggested by Gareth Hagger-Johnson<br />
<br />
----<br />
From SEED Magazine (Sept/Oct 2008 issue pg 89)<br />
<br />
<blockquote>If you play golf, you could be adding five years to your life. A new study<br />
shows that the death rate for Scandanavian golfers is 40% lower than for<br />
those who don't golf. The reason may be simple: Golfers walk, spend time<br />
outdoors, and developing social relationships. The social interaction can<br />
be especially important for the older age groups. Researchers have not<br />
ruled out the possibility that golfers simply live healthy lives in<br />
general, but they believe that the game itself does have health benefits.</blockquote><br />
<br />
Submitted by William Montante<br />
<br />
----<br />
<blockquote> "We're off by a factor of a lot."--Tony Miller, founder of Carol.com a company that hoped to sell about 200 healthcare policies a month but after eight months sold but a total of 160.<br />
<div align="right">Minneapolis Star Tribune. <br><br />
September 28, 2008</div><br><br />
<br />
Submitted by Paul Alper<br />
----<br />
<br />
The following Forsooths are from the October 2008 RRS<br />
<br />
<blockquote>If you do not have so many players, what can you do? There are 95 registered Brazilian players in the Championship League, 94 French players and 45 English players. When you have twice as few players as other countries it is difficult.<br />
<br />
<div align="right"> Dailey Telegraph'<br><br />
27 November 2007</div></blockquote><br />
----<br />
<blockquote>England have been drawn against their Euro 2008 nemeses Croatia for the 2010 World Cup South Africa qualifiers<br />
...It was almost inevitable that Sunday's World Cup draw would throw the two nations together again...<br />
----<br />
<div align="right"> BBC Neews Sport<br><br />
5 December 2007</div></blockquote><br />
----<br />
<blockquote>Michael Ballack's heart must have skipped a beat for a microsecond.<br />
<br />
<div align="right"> Sky Sports<br><br />
26 April 2008</div></blockquote><br />
<br />
==Discussion==<br />
<br />
Explane why each of these RSS Forsooths are Forsooths.<br />
<br />
== Understanding Uncertainty ==<br />
<br />
The website [http://understandinguncertainty.org/about Understanding Uncertainty] is maintained by [http://www.mrc-bsu.cam.ac.uk/BSUsite/AboutUs/People/davids.xml David Spiegelhalter ] at Cambridge University. The website provides modules that analize uncertainty issues written by Spiegelhalter with help by others. So far they have provided the following modules:<br />
<br />
Coincidences<br><br />
National Lottery<br><br />
Premier League<br><br />
What is Probability?<br><br />
Risk in the media<br><br />
How long are you going to live?<br><br />
<br />
When they are completed, a more detailed discussion appears in [http://plus.maths.org/issue48/index.html Cambridge Math Journal Plus]<br />
<br />
The most recent issue of Plus includes the article [http://plus.maths.org/issue48/risk/index.htmlUnderstanding uncertainty: How long will you live?] by Mike Pearson and David Spiegelhalter. As in previous modules this module includes elegent animations provided by Mike Pearson. <br />
<br />
The data for this module consists of UK interim life tables 1982-2006.<br />
<br />
In the first animation we see the age and the % Hazard = Chance of death before next birthday and the age of the individual lives evolve through time.<br />
<br />
In the second animation we can find the chance of death before our next birthday. We put in 83 and found that there is a 9.1% chance that we will die before our next birthday, <br />
<br />
From the third animation we find that our life expectance is 89. However in the fourth animation we find that, since we are:<br />
<br />
Non smoker<br> <br />
5 day a week Fruit/Veg<br> <br />
Moderate Alcohol<br> <br />
Physically Active<br><br />
<br />
our Expected Age of death is 91<br />
<br />
We think you will enjoy this and other of their modules.<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Are bad models to blame?==<br />
<br />
[http://bits.blogs.nytimes.com/2008/09/18/how-wall-streets-quants-lied-to-their-computers How Wall Street Lied to Its Computers], Saul Hansell, New York Times Technology Blog, September 18, 2008.<br />
<br />
There is a lot of speculation on why major Wall Street firms are reeling from piles of bad debt. These firms hire some of the best and brightest financial experts. These experts are supposed to manage risk to avoid this sort of problem.<br />
<br />
There is some speculation that this is just bad luck.<br />
<br />
<blockquote>the level of financial distress is “the equivalent of the 100-year flood,” in the words of Leslie Rahl, the president of Capital Market Risk Advisors, a consulting firm.</blockquote><br />
<br />
But that's only part of the story. Some of the blame comes from bad models.<br />
<br />
<blockquote>"There was a willful designing of the systems to measure the risks in a certain way that would not necessarily pick up all the right risks," said Gregg Berman, the co-head of the risk-management group at RiskMetrics, a software company spun out of JPMorgan.</blockquote><br />
<br />
Why would anyone deliberately use a bad model?<br />
<br />
<blockquote>Lying to your risk-management computer is like lying to your doctor. You just aren’t going to get the help you really need.</blockquote><br />
<br />
This may be a case of the fox being in charge of the hen house. Higher risk investments are attractive during good times because they offer greater levels of return than low risk investments. They have to offer greater returns, because they wouldn't be able to attract investors otherwise. But these greater returns will disappear if you have to hold back a large financial reserve to cover the downside risk. So there is a great temptation to pretend that high risk investments are really not high risk.<br />
<br />
How were these models flawed? One thought is that they used the wrong time horizon.<br />
<br />
<blockquote>One way they did this, Mr. Berman said, was to make sure the computer models looked at several years of trading history instead of just the last few months. The most important models calculate a measure known as Value at Risk — the amount of money you might lose in the worst plausible situation. They try to figure out what that worst case is by looking at how volatile markets have been in the past.</blockquote><br />
<br />
<blockquote>But since the markets were placid for several years (as mortgage bankers busily lent money to anyone with a pulse), the computers were slow to say that risk had increased as defaults started to rise.</blockquote><br />
<br />
<blockquote>It was like a weather forecaster in Houston last weekend talking about the onset of Hurricane Ike by giving the average wind speed for the previous month. </blockquote><br />
<br />
Another problem is that many new investments are far more complex than in the past.<br />
<br />
<blockquote>"New products, by definition, carry more risk,” [Ms. Rahl] said. The models should penalize investments that are complex, hard to understand and infrequently traded, she said. They didn’t.</blockquote><br />
<br />
Submitted by Steve Simon<br />
<br />
===Questions===<br />
<br />
1. This is just one of many examples of someone being pressured to produce results that skew the numbers in favor of a pre-ordained conclusion. What other examples are there?<br />
<br />
2. What protections need to be put into place to encourage the use of more accurate models?<br />
<br />
==Going for 2 points==<br />
<br />
The New York Times<br><br />
September 21, 2008<br><br> <br />
To the Sports Editor:<br />
<br />
Re ''[http://query.nytimes.com/gst/fullpage.html?res=9C02EFDA113AF935A2575AC0A96E9C8B63&partner=rssnyt&emc=rssIn Denver, a Rare Display of the Go-for-It Mentality],'' Sept. 16: Judy Battista's analysis of Mike Shanahan's decision to go for a late 2-point conversion in Denver's game against San Diego is statistically unsound. The relevant outcome is winning the game, not a successful conversion.<br />
<br />
If the probability of a point after succeeding is 0.99 and the probability of a 2-point conversion succeeding (for the Broncos) is 0.536, the probability of winning in extra time is 0.5 and the probability of another score in regular time is small, then the probability of winning with a 2-point attempt is 0.536. and the probability of winning with a P.A.T (Point After Touchdown). is 0.99 times 0.5, or 0.495. So the odds favor the 2-point attempt, not the P.A.T. Home-field advantage and other factors may change these probabilities, but the fact remains that the 2-point try is hardly a reckless gamble in this situation.<br />
<br />
<div align="right">Rod Little <br><br />
Ann Arbor, Mich</div><br><br />
<br />
===Discussion===<br />
<br />
(1) What do you think of Little's analysis?<br />
<br />
(2) Do you think that any of the probabilities Little mentions are known to three decimal points?<br />
<br />
Submitted by Laurie Snell<br />
<br />
==A chance to get rich==<br />
<br />
The wild swings of the stock market provided a chance to get rich. It reminded me of one of my favorite articles reviewed by Chance News. <br />
<br />
Seen From a Rut, the Lottery Is Essential<br />
The New York Times<br />
July 16, 1996<br />
<br />
To the Editor:<br />
<br />
<blockquote>Your July 14 Week in Review article on lottery advertising repeats stereotypes about lottery players' being poor and uneducated and swept up into a gambling addiction. No doubt many are. But Gov. George E. Pataki's statement that "it has always bothered me to hold up the prospect of instant riches" could also be recast as, "I want to take away the only prospect poor people have of getting out of their rut."<br><br><br />
<br />
Before lotteries, other options existed for people to improve their lives, and the barriers were not so high. Graduate education today is expensive; many professions require training as well as licensing, and investing in stocks requires substantial equity. Most people are not so brilliant that they can start an Apple computer company in their garages. So, playing the lottery becomes a good investment when no alternative is better.<br><br><br />
<br />
Lottery players know that the odds are stacked against them, but they don't have to spend a lot of money. Quite a few win regularly. Many who play Lotto or Take 5 use wheeling systems, which, contrary to statements by lottery officials, do increase the chances of winning. I know; I play Lotto and I've won everything except the jackpot, and I win several times a year.<br><br><br />
<br />
Yes, I have lost more than I've won. But in the tedious world I inhabit along with so many other New Yorkers, I've bought a fantasy. If I ever win the jackpot, I'll wave to you from Sutton Place.</blockquote><br />
<br />
JOHN P. RASH New York, July 14, 1996<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Wikipedia vandalism to U.S. Senators==<br />
<br />
A recent [http://digg.com/politics/McCain_raped_wife_Obama_a_nudist_and_Hillary_has_a_penis methodical study] of Wikipedia's one hundred articles about the 100 U.S. Senators reveals that, on average, these articles are mildly vandalized to egregiously defamatory for about 1.63 hours per day.<br />
<br />
In all, the median duration of a damaged edit was 6 minutes, but the mean duration was 1,440 minutes (exactly 24 hours). These 100 articles were viewed approximately 12.8 million times in the fourth quarter of 2007. Over 378,000 of those views could be considered "damaged", yielding a 2.96% rate of damaged views. There were about 13.2 million article-minutes during the quarter, and over 901,000 of those article-minutes were in a damaged state -- 6.80%.<br />
<br />
The entire quarter's worth of data is available within [http://spreadsheets.google.com/pub?key=psAWteTSyixEB98YcV-5VEw a Google spreadsheet], where the study's organizer is available for private contact.<br />
<br />
===Discussion===<br />
<br />
(1) Were most of the vandalized edits made by anonymous IP addresses or "registered" users of Wikipedia? Why does Wikipedia allow anonymous IP addresses to modify articles about named living persons?<br />
<br />
(2) What constitutes an "attractive nuisance"? What online entities were intended to be protected by Section 230 of the Communications Decency Act? Is Wikipedia merely an "interactive computer service"?<br />
<br />
(3) Was this survey's methodology flawed in substantial ways? How so?<br />
<br />
Submitted by Gregory Kohs</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_40&diff=6056Chance News 402008-10-08T16:39:51Z<p>Thekohser: /* Wikipedia vandalism to U.S. Senators */ Update</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote>When I worked at the Labor Party think tank, trying to talk about these issues [oppression of Muslim women], people always accused me of failing to back up my arguments with data. But hard numbers were completely unavailable. When I tried to find out about honor killings, for instance-how many girls were killed every year in Holland by their fathers and brothers because of their precious family honor-civil servants at the Ministry of Justice would tell me, "We don't register murders based on that category of motivation. It would stigmatize one group in society." The Dutch government registered the number of drug-related killings and traffic accidents every year, but not the number of honor killings, because no Dutch official wanted to recognize that this kind of murder happened on a regular basis.</blockquote><br />
<br />
<div align=right>Aayan Hirsi Ali<br><b>Infidel</b>, Free Press: New York NY<br> pages 295-296.</div><br />
<br />
Suggested by Steve Simon<br />
<br />
==Forsooth==<br />
<br />
From the [http://www.independent.co.uk/ Independent], 13/09/08:<br />
<blockquote>Last week, a formatting error led to us inadvertently suggesting that there was a one in 1,019 chance of the world ending before this edition. That should have read, er, one in 10<SUP>19</SUP> – rather less likely. Sorry. Feel free to remove the crash helmet.</blockquote><br />
<br />
Suggested by Gareth Hagger-Johnson<br />
<br />
----<br />
From SEED Magazine (Sept/Oct 2008 issue pg 89)<br />
<br />
<blockquote>If you play golf, you could be adding five years to your life. A new study<br />
shows that the death rate for Scandanavian golfers is 40% lower than for<br />
those who don't golf. The reason may be simple: Golfers walk, spend time<br />
outdoors, and developing social relationships. The social interaction can<br />
be especially important for the older age groups. Researchers have not<br />
ruled out the possibility that golfers simply live healthy lives in<br />
general, but they believe that the game itself does have health benefits.</blockquote><br />
<br />
Submitted by William Montante<br />
<br />
----<br />
<blockquote> "We're off by a factor of a lot."--Tony Miller, founder of Carol.com a company that hoped to sell about 200 healthcare policies a month but after eight months sold but a total of 160.<br />
<div align="right">Minneapolis Star Tribune. <br><br />
September 28, 2008</div><br><br />
<br />
Submitted by Paul Alper<br />
----<br />
<br />
The following Forsooths are from the October 2008 RRS<br />
<br />
<blockquote>If you do not have so many players, what can you do? There are 95 registered Brazilian players in the Championship League, 94 French players and 45 English players. When you have twice as few players as other countries it is difficult.<br />
<br />
<div align="right"> Dailey Telegraph'<br><br />
27 November 2007</div></blockquote><br />
----<br />
<blockquote>England have been drawn against their Euro 2008 nemeses Croatia for the 2010 World Cup South Africa qualifiers<br />
...It was almost inevitable that Sunday's World Cup draw would throw the two nations together again...<br />
----<br />
<div align="right"> BBC Neews Sport<br><br />
5 December 2007</div></blockquote><br />
----<br />
<blockquote>Michael Ballack's heart must have skipped a beat for a microsecond.<br />
<br />
<div align="right"> Sky Sports<br><br />
26 April 2008</div></blockquote><br />
<br />
==Discussion==<br />
<br />
Explane why each of these RSS Forsooths are Forsooths.<br />
<br />
== Understanding Uncertainty ==<br />
<br />
The website [http://understandinguncertainty.org/about Understanding Uncertainty] is maintained by [http://www.mrc-bsu.cam.ac.uk/BSUsite/AboutUs/People/davids.xml David Spiegelhalter ] at Cambridge University. The website provides modules that analize uncertainty issues written by Spiegelhalter with help by others. So far they have provided the following modules:<br />
<br />
Coincidences<br><br />
National Lottery<br><br />
Premier League<br><br />
What is Probability?<br><br />
Risk in the media<br><br />
How long are you going to live?<br><br />
<br />
When they are completed, a more detailed discussion appears in [http://plus.maths.org/issue48/index.html Cambridge Math Journal Plus]<br />
<br />
The most recent issue of Plus includes the article [http://plus.maths.org/issue48/risk/index.htmlUnderstanding uncertainty: How long will you live?] by Mike Pearson and David Spiegelhalter. As in previous modules this module includes elegent animations provided by Mike Pearson. <br />
<br />
The data for this module consists of UK interim life tables 1982-2006.<br />
<br />
In the first animation we see the age and the % Hazard = Chance of death before next birthday and the age of the individual lives evolve through time.<br />
<br />
In the second animation we can find the chance of death before our next birthday. We put in 83 and found that there is a 9.1% chance that we will die before our next birthday, <br />
<br />
From the third animation we find that our life expectance is 89. However in the fourth animation we find that, since we are:<br />
<br />
Non smoker<br> <br />
5 day a week Fruit/Veg<br> <br />
Moderate Alcohol<br> <br />
Physically Active<br><br />
<br />
our Expected Age of death is 91<br />
<br />
We think you will enjoy this and other of their modules.<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Are bad models to blame?==<br />
<br />
[http://bits.blogs.nytimes.com/2008/09/18/how-wall-streets-quants-lied-to-their-computers How Wall Street Lied to Its Computers], Saul Hansell, New York Times Technology Blog, September 18, 2008.<br />
<br />
There is a lot of speculation on why major Wall Street firms are reeling from piles of bad debt. These firms hire some of the best and brightest financial experts. These experts are supposed to manage risk to avoid this sort of problem.<br />
<br />
There is some speculation that this is just bad luck.<br />
<br />
<blockquote>the level of financial distress is “the equivalent of the 100-year flood,” in the words of Leslie Rahl, the president of Capital Market Risk Advisors, a consulting firm.</blockquote><br />
<br />
But that's only part of the story. Some of the blame comes from bad models.<br />
<br />
<blockquote>"There was a willful designing of the systems to measure the risks in a certain way that would not necessarily pick up all the right risks," said Gregg Berman, the co-head of the risk-management group at RiskMetrics, a software company spun out of JPMorgan.</blockquote><br />
<br />
Why would anyone deliberately use a bad model?<br />
<br />
<blockquote>Lying to your risk-management computer is like lying to your doctor. You just aren’t going to get the help you really need.</blockquote><br />
<br />
This may be a case of the fox being in charge of the hen house. Higher risk investments are attractive during good times because they offer greater levels of return than low risk investments. They have to offer greater returns, because they wouldn't be able to attract investors otherwise. But these greater returns will disappear if you have to hold back a large financial reserve to cover the downside risk. So there is a great temptation to pretend that high risk investments are really not high risk.<br />
<br />
How were these models flawed? One thought is that they used the wrong time horizon.<br />
<br />
<blockquote>One way they did this, Mr. Berman said, was to make sure the computer models looked at several years of trading history instead of just the last few months. The most important models calculate a measure known as Value at Risk — the amount of money you might lose in the worst plausible situation. They try to figure out what that worst case is by looking at how volatile markets have been in the past.</blockquote><br />
<br />
<blockquote>But since the markets were placid for several years (as mortgage bankers busily lent money to anyone with a pulse), the computers were slow to say that risk had increased as defaults started to rise.</blockquote><br />
<br />
<blockquote>It was like a weather forecaster in Houston last weekend talking about the onset of Hurricane Ike by giving the average wind speed for the previous month. </blockquote><br />
<br />
Another problem is that many new investments are far more complex than in the past.<br />
<br />
<blockquote>"New products, by definition, carry more risk,” [Ms. Rahl] said. The models should penalize investments that are complex, hard to understand and infrequently traded, she said. They didn’t.</blockquote><br />
<br />
Submitted by Steve Simon<br />
<br />
===Questions===<br />
<br />
1. This is just one of many examples of someone being pressured to produce results that skew the numbers in favor of a pre-ordained conclusion. What other examples are there?<br />
<br />
2. What protections need to be put into place to encourage the use of more accurate models?<br />
<br />
==Going for 2 points==<br />
<br />
The New York Times<br><br />
September 21, 2008<br><br> <br />
To the Sports Editor:<br />
<br />
Re ''[http://query.nytimes.com/gst/fullpage.html?res=9C02EFDA113AF935A2575AC0A96E9C8B63&partner=rssnyt&emc=rssIn Denver, a Rare Display of the Go-for-It Mentality],'' Sept. 16: Judy Battista's analysis of Mike Shanahan's decision to go for a late 2-point conversion in Denver's game against San Diego is statistically unsound. The relevant outcome is winning the game, not a successful conversion.<br />
<br />
If the probability of a point after succeeding is 0.99 and the probability of a 2-point conversion succeeding (for the Broncos) is 0.536, the probability of winning in extra time is 0.5 and the probability of another score in regular time is small, then the probability of winning with a 2-point attempt is 0.536. and the probability of winning with a P.A.T (Point After Touchdown). is 0.99 times 0.5, or 0.495. So the odds favor the 2-point attempt, not the P.A.T. Home-field advantage and other factors may change these probabilities, but the fact remains that the 2-point try is hardly a reckless gamble in this situation.<br />
<br />
<div align="right">Rod Little <br><br />
Ann Arbor, Mich</div><br><br />
<br />
===Discussion===<br />
<br />
(1) What do you think of Little's analysis?<br />
<br />
(2) Do you think that any of the probabilities Little mentions are known to three decimal points?<br />
<br />
Submitted by Laurie Snell<br />
<br />
==A chance to get rich==<br />
<br />
The wild swings of the stock market provided a chance to get rich. It reminded me of one of my favorite articles reviewed by Chance News. <br />
<br />
Seen From a Rut, the Lottery Is Essential<br />
The New York Times<br />
July 16, 1996<br />
<br />
To the Editor:<br />
<br />
<blockquote>Your July 14 Week in Review article on lottery advertising repeats stereotypes about lottery players' being poor and uneducated and swept up into a gambling addiction. No doubt many are. But Gov. George E. Pataki's statement that "it has always bothered me to hold up the prospect of instant riches" could also be recast as, "I want to take away the only prospect poor people have of getting out of their rut."<br><br><br />
<br />
Before lotteries, other options existed for people to improve their lives, and the barriers were not so high. Graduate education today is expensive; many professions require training as well as licensing, and investing in stocks requires substantial equity. Most people are not so brilliant that they can start an Apple computer company in their garages. So, playing the lottery becomes a good investment when no alternative is better.<br><br><br />
<br />
Lottery players know that the odds are stacked against them, but they don't have to spend a lot of money. Quite a few win regularly. Many who play Lotto or Take 5 use wheeling systems, which, contrary to statements by lottery officials, do increase the chances of winning. I know; I play Lotto and I've won everything except the jackpot, and I win several times a year.<br><br><br />
<br />
Yes, I have lost more than I've won. But in the tedious world I inhabit along with so many other New Yorkers, I've bought a fantasy. If I ever win the jackpot, I'll wave to you from Sutton Place.</blockquote><br />
<br />
JOHN P. RASH New York, July 14, 1996<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Wikipedia vandalism to U.S. Senators==<br />
<br />
A recent [http://digg.com/politics/McCain_raped_wife_Obama_a_nudist_and_Hillary_has_a_penis methodical study] of Wikipedia's one hundred articles about the 100 U.S. Senators reveals that, on average, these articles are mildly vandalized to egregiously defamatory for about 1.63 hours per day.<br />
<br />
In all, the median duration of a damaged edit was 6 minutes, but the mean duration was 1,440 minutes (exactly 24 hours). These 100 articles were viewed approximately 12.8 million times in the fourth quarter of 2007. Over 378,000 of those views could be considered "damaged", yielding a 2.96% rate of damaged views. There were about 13.2 million article-minutes during the quarter, and over 901,000 of those article-minutes were in a damaged state -- 6.80%.<br />
<br />
The entire quarter's worth of data is available within [<br />
http://spreadsheets.google.com/pub?key=psAWteTSyixEB98YcV-5VEw a Google spreadsheet], where the study's organizer is available for private contact.<br />
<br />
===Discussion===<br />
<br />
(1) Were most of the vandalized edits made by anonymous IP addresses or "registered" users of Wikipedia? Why does Wikipedia allow anonymous IP addresses to modify articles about named living persons?<br />
<br />
(2) What constitutes an "attractive nuisance"? What online entities were intended to be protected by Section 230 of the Communications Decency Act? Is Wikipedia merely an "interactive computer service"?<br />
<br />
(3) Was this survey's methodology flawed in substantial ways? How so?<br />
<br />
Submitted by Gregory Kohs</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_40&diff=6055Chance News 402008-10-08T16:33:16Z<p>Thekohser: /* Wikipedia vandalism to U.S. Senators */ Update</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote>When I worked at the Labor Party think tank, trying to talk about these issues [oppression of Muslim women], people always accused me of failing to back up my arguments with data. But hard numbers were completely unavailable. When I tried to find out about honor killings, for instance-how many girls were killed every year in Holland by their fathers and brothers because of their precious family honor-civil servants at the Ministry of Justice would tell me, "We don't register murders based on that category of motivation. It would stigmatize one group in society." The Dutch government registered the number of drug-related killings and traffic accidents every year, but not the number of honor killings, because no Dutch official wanted to recognize that this kind of murder happened on a regular basis.</blockquote><br />
<br />
<div align=right>Aayan Hirsi Ali<br><b>Infidel</b>, Free Press: New York NY<br> pages 295-296.</div><br />
<br />
Suggested by Steve Simon<br />
<br />
==Forsooth==<br />
<br />
From the [http://www.independent.co.uk/ Independent], 13/09/08:<br />
<blockquote>Last week, a formatting error led to us inadvertently suggesting that there was a one in 1,019 chance of the world ending before this edition. That should have read, er, one in 10<SUP>19</SUP> – rather less likely. Sorry. Feel free to remove the crash helmet.</blockquote><br />
<br />
Suggested by Gareth Hagger-Johnson<br />
<br />
----<br />
From SEED Magazine (Sept/Oct 2008 issue pg 89)<br />
<br />
<blockquote>If you play golf, you could be adding five years to your life. A new study<br />
shows that the death rate for Scandanavian golfers is 40% lower than for<br />
those who don't golf. The reason may be simple: Golfers walk, spend time<br />
outdoors, and developing social relationships. The social interaction can<br />
be especially important for the older age groups. Researchers have not<br />
ruled out the possibility that golfers simply live healthy lives in<br />
general, but they believe that the game itself does have health benefits.</blockquote><br />
<br />
Submitted by William Montante<br />
<br />
----<br />
<blockquote> "We're off by a factor of a lot."--Tony Miller, founder of Carol.com a company that hoped to sell about 200 healthcare policies a month but after eight months sold but a total of 160.<br />
<div align="right">Minneapolis Star Tribune. <br><br />
September 28, 2008</div><br><br />
<br />
Submitted by Paul Alper<br />
----<br />
<br />
The following Forsooths are from the October 2008 RRS<br />
<br />
<blockquote>If you do not have so many players, what can you do? There are 95 registered Brazilian players in the Championship League, 94 French players and 45 English players. When you have twice as few players as other countries it is difficult.<br />
<br />
<div align="right"> Dailey Telegraph'<br><br />
27 November 2007</div></blockquote><br />
----<br />
<blockquote>England have been drawn against their Euro 2008 nemeses Croatia for the 2010 World Cup South Africa qualifiers<br />
...It was almost inevitable that Sunday's World Cup draw would throw the two nations together again...<br />
----<br />
<div align="right"> BBC Neews Sport<br><br />
5 December 2007</div></blockquote><br />
----<br />
<blockquote>Michael Ballack's heart must have skipped a beat for a microsecond.<br />
<br />
<div align="right"> Sky Sports<br><br />
26 April 2008</div></blockquote><br />
<br />
==Discussion==<br />
<br />
Explane why each of these RSS Forsooths are Forsooths.<br />
<br />
== Understanding Uncertainty ==<br />
<br />
The website [http://understandinguncertainty.org/about Understanding Uncertainty] is maintained by [http://www.mrc-bsu.cam.ac.uk/BSUsite/AboutUs/People/davids.xml David Spiegelhalter ] at Cambridge University. The website provides modules that analize uncertainty issues written by Spiegelhalter with help by others. So far they have provided the following modules:<br />
<br />
Coincidences<br><br />
National Lottery<br><br />
Premier League<br><br />
What is Probability?<br><br />
Risk in the media<br><br />
How long are you going to live?<br><br />
<br />
When they are completed, a more detailed discussion appears in [http://plus.maths.org/issue48/index.html Cambridge Math Journal Plus]<br />
<br />
The most recent issue of Plus includes the article [http://plus.maths.org/issue48/risk/index.htmlUnderstanding uncertainty: How long will you live?] by Mike Pearson and David Spiegelhalter. As in previous modules this module includes elegent animations provided by Mike Pearson. <br />
<br />
The data for this module consists of UK interim life tables 1982-2006.<br />
<br />
In the first animation we see the age and the % Hazard = Chance of death before next birthday and the age of the individual lives evolve through time.<br />
<br />
In the second animation we can find the chance of death before our next birthday. We put in 83 and found that there is a 9.1% chance that we will die before our next birthday, <br />
<br />
From the third animation we find that our life expectance is 89. However in the fourth animation we find that, since we are:<br />
<br />
Non smoker<br> <br />
5 day a week Fruit/Veg<br> <br />
Moderate Alcohol<br> <br />
Physically Active<br><br />
<br />
our Expected Age of death is 91<br />
<br />
We think you will enjoy this and other of their modules.<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Are bad models to blame?==<br />
<br />
[http://bits.blogs.nytimes.com/2008/09/18/how-wall-streets-quants-lied-to-their-computers How Wall Street Lied to Its Computers], Saul Hansell, New York Times Technology Blog, September 18, 2008.<br />
<br />
There is a lot of speculation on why major Wall Street firms are reeling from piles of bad debt. These firms hire some of the best and brightest financial experts. These experts are supposed to manage risk to avoid this sort of problem.<br />
<br />
There is some speculation that this is just bad luck.<br />
<br />
<blockquote>the level of financial distress is “the equivalent of the 100-year flood,” in the words of Leslie Rahl, the president of Capital Market Risk Advisors, a consulting firm.</blockquote><br />
<br />
But that's only part of the story. Some of the blame comes from bad models.<br />
<br />
<blockquote>"There was a willful designing of the systems to measure the risks in a certain way that would not necessarily pick up all the right risks," said Gregg Berman, the co-head of the risk-management group at RiskMetrics, a software company spun out of JPMorgan.</blockquote><br />
<br />
Why would anyone deliberately use a bad model?<br />
<br />
<blockquote>Lying to your risk-management computer is like lying to your doctor. You just aren’t going to get the help you really need.</blockquote><br />
<br />
This may be a case of the fox being in charge of the hen house. Higher risk investments are attractive during good times because they offer greater levels of return than low risk investments. They have to offer greater returns, because they wouldn't be able to attract investors otherwise. But these greater returns will disappear if you have to hold back a large financial reserve to cover the downside risk. So there is a great temptation to pretend that high risk investments are really not high risk.<br />
<br />
How were these models flawed? One thought is that they used the wrong time horizon.<br />
<br />
<blockquote>One way they did this, Mr. Berman said, was to make sure the computer models looked at several years of trading history instead of just the last few months. The most important models calculate a measure known as Value at Risk — the amount of money you might lose in the worst plausible situation. They try to figure out what that worst case is by looking at how volatile markets have been in the past.</blockquote><br />
<br />
<blockquote>But since the markets were placid for several years (as mortgage bankers busily lent money to anyone with a pulse), the computers were slow to say that risk had increased as defaults started to rise.</blockquote><br />
<br />
<blockquote>It was like a weather forecaster in Houston last weekend talking about the onset of Hurricane Ike by giving the average wind speed for the previous month. </blockquote><br />
<br />
Another problem is that many new investments are far more complex than in the past.<br />
<br />
<blockquote>"New products, by definition, carry more risk,” [Ms. Rahl] said. The models should penalize investments that are complex, hard to understand and infrequently traded, she said. They didn’t.</blockquote><br />
<br />
Submitted by Steve Simon<br />
<br />
===Questions===<br />
<br />
1. This is just one of many examples of someone being pressured to produce results that skew the numbers in favor of a pre-ordained conclusion. What other examples are there?<br />
<br />
2. What protections need to be put into place to encourage the use of more accurate models?<br />
<br />
==Going for 2 points==<br />
<br />
The New York Times<br><br />
September 21, 2008<br><br> <br />
To the Sports Editor:<br />
<br />
Re ''[http://query.nytimes.com/gst/fullpage.html?res=9C02EFDA113AF935A2575AC0A96E9C8B63&partner=rssnyt&emc=rssIn Denver, a Rare Display of the Go-for-It Mentality],'' Sept. 16: Judy Battista's analysis of Mike Shanahan's decision to go for a late 2-point conversion in Denver's game against San Diego is statistically unsound. The relevant outcome is winning the game, not a successful conversion.<br />
<br />
If the probability of a point after succeeding is 0.99 and the probability of a 2-point conversion succeeding (for the Broncos) is 0.536, the probability of winning in extra time is 0.5 and the probability of another score in regular time is small, then the probability of winning with a 2-point attempt is 0.536. and the probability of winning with a P.A.T (Point After Touchdown). is 0.99 times 0.5, or 0.495. So the odds favor the 2-point attempt, not the P.A.T. Home-field advantage and other factors may change these probabilities, but the fact remains that the 2-point try is hardly a reckless gamble in this situation.<br />
<br />
<div align="right">Rod Little <br><br />
Ann Arbor, Mich</div><br><br />
<br />
===Discussion===<br />
<br />
(1) What do you think of Little's analysis?<br />
<br />
(2) Do you think that any of the probabilities Little mentions are known to three decimal points?<br />
<br />
Submitted by Laurie Snell<br />
<br />
==A chance to get rich==<br />
<br />
The wild swings of the stock market provided a chance to get rich. It reminded me of one of my favorite articles reviewed by Chance News. <br />
<br />
Seen From a Rut, the Lottery Is Essential<br />
The New York Times<br />
July 16, 1996<br />
<br />
To the Editor:<br />
<br />
<blockquote>Your July 14 Week in Review article on lottery advertising repeats stereotypes about lottery players' being poor and uneducated and swept up into a gambling addiction. No doubt many are. But Gov. George E. Pataki's statement that "it has always bothered me to hold up the prospect of instant riches" could also be recast as, "I want to take away the only prospect poor people have of getting out of their rut."<br><br><br />
<br />
Before lotteries, other options existed for people to improve their lives, and the barriers were not so high. Graduate education today is expensive; many professions require training as well as licensing, and investing in stocks requires substantial equity. Most people are not so brilliant that they can start an Apple computer company in their garages. So, playing the lottery becomes a good investment when no alternative is better.<br><br><br />
<br />
Lottery players know that the odds are stacked against them, but they don't have to spend a lot of money. Quite a few win regularly. Many who play Lotto or Take 5 use wheeling systems, which, contrary to statements by lottery officials, do increase the chances of winning. I know; I play Lotto and I've won everything except the jackpot, and I win several times a year.<br><br><br />
<br />
Yes, I have lost more than I've won. But in the tedious world I inhabit along with so many other New Yorkers, I've bought a fantasy. If I ever win the jackpot, I'll wave to you from Sutton Place.</blockquote><br />
<br />
JOHN P. RASH New York, July 14, 1996<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Wikipedia vandalism to U.S. Senators==<br />
<br />
A recent [http://digg.com/politics/McCain_raped_wife_Obama_a_nudist_and_Hillary_has_a_penis methodical study] of Wikipedia's one hundred articles about the 100 U.S. Senators reveals that, on average, these articles are mildly vandalized to egregiously defamatory for about 1.63 hours per day.<br />
<br />
In all, the median duration of a damaged edit was 6 minutes, but the mean duration was 1,440 minutes (exactly 24 hours). These 100 articles were viewed approximately 12.8 million times in the fourth quarter of 2007. Over 378,000 of those views could be considered "damaged", yielding a 2.96% rate of damaged views. There were about 13.2 million article-minutes during the quarter, and over 901,000 of those article-minutes were in a damaged state -- 6.80%.<br />
<br />
The entire quarter's worth of data is available within [<br />
http://spreadsheets.google.com/pub?key=psAWteTSyixEB98YcV-5VEw a Google spreadsheet], where the study's organizer is available for private contact.<br />
<br />
===Discussion===<br />
<br />
(1) Were most of the vandalized edits made by anonymous IP addresses or "registered" users of Wikipedia? Why does Wikipedia allow anonymous IP addresses to modify articles about living public officials?<br />
<br />
(2) What constitutes an "attractive nuisance"? What online entities were intended to be protected by Section 230 of the Communications Decency Act? Is Wikipedia merely an "interactive computer service"?<br />
<br />
Submitted by Gregory Kohs</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_40&diff=6054Chance News 402008-10-08T16:27:25Z<p>Thekohser: /* Wikipedia vandalism to U.S. Senators */</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote>When I worked at the Labor Party think tank, trying to talk about these issues [oppression of Muslim women], people always accused me of failing to back up my arguments with data. But hard numbers were completely unavailable. When I tried to find out about honor killings, for instance-how many girls were killed every year in Holland by their fathers and brothers because of their precious family honor-civil servants at the Ministry of Justice would tell me, "We don't register murders based on that category of motivation. It would stigmatize one group in society." The Dutch government registered the number of drug-related killings and traffic accidents every year, but not the number of honor killings, because no Dutch official wanted to recognize that this kind of murder happened on a regular basis.</blockquote><br />
<br />
<div align=right>Aayan Hirsi Ali<br><b>Infidel</b>, Free Press: New York NY<br> pages 295-296.</div><br />
<br />
Suggested by Steve Simon<br />
<br />
==Forsooth==<br />
<br />
From the [http://www.independent.co.uk/ Independent], 13/09/08:<br />
<blockquote>Last week, a formatting error led to us inadvertently suggesting that there was a one in 1,019 chance of the world ending before this edition. That should have read, er, one in 10<SUP>19</SUP> – rather less likely. Sorry. Feel free to remove the crash helmet.</blockquote><br />
<br />
Suggested by Gareth Hagger-Johnson<br />
<br />
----<br />
From SEED Magazine (Sept/Oct 2008 issue pg 89)<br />
<br />
<blockquote>If you play golf, you could be adding five years to your life. A new study<br />
shows that the death rate for Scandanavian golfers is 40% lower than for<br />
those who don't golf. The reason may be simple: Golfers walk, spend time<br />
outdoors, and developing social relationships. The social interaction can<br />
be especially important for the older age groups. Researchers have not<br />
ruled out the possibility that golfers simply live healthy lives in<br />
general, but they believe that the game itself does have health benefits.</blockquote><br />
<br />
Submitted by William Montante<br />
<br />
----<br />
<blockquote> "We're off by a factor of a lot."--Tony Miller, founder of Carol.com a company that hoped to sell about 200 healthcare policies a month but after eight months sold but a total of 160.<br />
<div align="right">Minneapolis Star Tribune. <br><br />
September 28, 2008</div><br><br />
<br />
Submitted by Paul Alper<br />
----<br />
<br />
The following Forsooths are from the October 2008 RRS<br />
<br />
<blockquote>If you do not have so many players, what can you do? There are 95 registered Brazilian players in the Championship League, 94 French players and 45 English players. When you have twice as few players as other countries it is difficult.<br />
<br />
<div align="right"> Dailey Telegraph'<br><br />
27 November 2007</div></blockquote><br />
----<br />
<blockquote>England have been drawn against their Euro 2008 nemeses Croatia for the 2010 World Cup South Africa qualifiers<br />
...It was almost inevitable that Sunday's World Cup draw would throw the two nations together again...<br />
----<br />
<div align="right"> BBC Neews Sport<br><br />
5 December 2007</div></blockquote><br />
----<br />
<blockquote>Michael Ballack's heart must have skipped a beat for a microsecond.<br />
<br />
<div align="right"> Sky Sports<br><br />
26 April 2008</div></blockquote><br />
<br />
==Discussion==<br />
<br />
Explane why each of these RSS Forsooths are Forsooths.<br />
<br />
== Understanding Uncertainty ==<br />
<br />
The website [http://understandinguncertainty.org/about Understanding Uncertainty] is maintained by [http://www.mrc-bsu.cam.ac.uk/BSUsite/AboutUs/People/davids.xml David Spiegelhalter ] at Cambridge University. The website provides modules that analize uncertainty issues written by Spiegelhalter with help by others. So far they have provided the following modules:<br />
<br />
Coincidences<br><br />
National Lottery<br><br />
Premier League<br><br />
What is Probability?<br><br />
Risk in the media<br><br />
How long are you going to live?<br><br />
<br />
When they are completed, a more detailed discussion appears in [http://plus.maths.org/issue48/index.html Cambridge Math Journal Plus]<br />
<br />
The most recent issue of Plus includes the article [http://plus.maths.org/issue48/risk/index.htmlUnderstanding uncertainty: How long will you live?] by Mike Pearson and David Spiegelhalter. As in previous modules this module includes elegent animations provided by Mike Pearson. <br />
<br />
The data for this module consists of UK interim life tables 1982-2006.<br />
<br />
In the first animation we see the age and the % Hazard = Chance of death before next birthday and the age of the individual lives evolve through time.<br />
<br />
In the second animation we can find the chance of death before our next birthday. We put in 83 and found that there is a 9.1% chance that we will die before our next birthday, <br />
<br />
From the third animation we find that our life expectance is 89. However in the fourth animation we find that, since we are:<br />
<br />
Non smoker<br> <br />
5 day a week Fruit/Veg<br> <br />
Moderate Alcohol<br> <br />
Physically Active<br><br />
<br />
our Expected Age of death is 91<br />
<br />
We think you will enjoy this and other of their modules.<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Are bad models to blame?==<br />
<br />
[http://bits.blogs.nytimes.com/2008/09/18/how-wall-streets-quants-lied-to-their-computers How Wall Street Lied to Its Computers], Saul Hansell, New York Times Technology Blog, September 18, 2008.<br />
<br />
There is a lot of speculation on why major Wall Street firms are reeling from piles of bad debt. These firms hire some of the best and brightest financial experts. These experts are supposed to manage risk to avoid this sort of problem.<br />
<br />
There is some speculation that this is just bad luck.<br />
<br />
<blockquote>the level of financial distress is “the equivalent of the 100-year flood,” in the words of Leslie Rahl, the president of Capital Market Risk Advisors, a consulting firm.</blockquote><br />
<br />
But that's only part of the story. Some of the blame comes from bad models.<br />
<br />
<blockquote>"There was a willful designing of the systems to measure the risks in a certain way that would not necessarily pick up all the right risks," said Gregg Berman, the co-head of the risk-management group at RiskMetrics, a software company spun out of JPMorgan.</blockquote><br />
<br />
Why would anyone deliberately use a bad model?<br />
<br />
<blockquote>Lying to your risk-management computer is like lying to your doctor. You just aren’t going to get the help you really need.</blockquote><br />
<br />
This may be a case of the fox being in charge of the hen house. Higher risk investments are attractive during good times because they offer greater levels of return than low risk investments. They have to offer greater returns, because they wouldn't be able to attract investors otherwise. But these greater returns will disappear if you have to hold back a large financial reserve to cover the downside risk. So there is a great temptation to pretend that high risk investments are really not high risk.<br />
<br />
How were these models flawed? One thought is that they used the wrong time horizon.<br />
<br />
<blockquote>One way they did this, Mr. Berman said, was to make sure the computer models looked at several years of trading history instead of just the last few months. The most important models calculate a measure known as Value at Risk — the amount of money you might lose in the worst plausible situation. They try to figure out what that worst case is by looking at how volatile markets have been in the past.</blockquote><br />
<br />
<blockquote>But since the markets were placid for several years (as mortgage bankers busily lent money to anyone with a pulse), the computers were slow to say that risk had increased as defaults started to rise.</blockquote><br />
<br />
<blockquote>It was like a weather forecaster in Houston last weekend talking about the onset of Hurricane Ike by giving the average wind speed for the previous month. </blockquote><br />
<br />
Another problem is that many new investments are far more complex than in the past.<br />
<br />
<blockquote>"New products, by definition, carry more risk,” [Ms. Rahl] said. The models should penalize investments that are complex, hard to understand and infrequently traded, she said. They didn’t.</blockquote><br />
<br />
Submitted by Steve Simon<br />
<br />
===Questions===<br />
<br />
1. This is just one of many examples of someone being pressured to produce results that skew the numbers in favor of a pre-ordained conclusion. What other examples are there?<br />
<br />
2. What protections need to be put into place to encourage the use of more accurate models?<br />
<br />
==Going for 2 points==<br />
<br />
The New York Times<br><br />
September 21, 2008<br><br> <br />
To the Sports Editor:<br />
<br />
Re ''[http://query.nytimes.com/gst/fullpage.html?res=9C02EFDA113AF935A2575AC0A96E9C8B63&partner=rssnyt&emc=rssIn Denver, a Rare Display of the Go-for-It Mentality],'' Sept. 16: Judy Battista's analysis of Mike Shanahan's decision to go for a late 2-point conversion in Denver's game against San Diego is statistically unsound. The relevant outcome is winning the game, not a successful conversion.<br />
<br />
If the probability of a point after succeeding is 0.99 and the probability of a 2-point conversion succeeding (for the Broncos) is 0.536, the probability of winning in extra time is 0.5 and the probability of another score in regular time is small, then the probability of winning with a 2-point attempt is 0.536. and the probability of winning with a P.A.T (Point After Touchdown). is 0.99 times 0.5, or 0.495. So the odds favor the 2-point attempt, not the P.A.T. Home-field advantage and other factors may change these probabilities, but the fact remains that the 2-point try is hardly a reckless gamble in this situation.<br />
<br />
<div align="right">Rod Little <br><br />
Ann Arbor, Mich</div><br><br />
<br />
===Discussion===<br />
<br />
(1) What do you think of Little's analysis?<br />
<br />
(2) Do you think that any of the probabilities Little mentions are known to three decimal points?<br />
<br />
Submitted by Laurie Snell<br />
<br />
==A chance to get rich==<br />
<br />
The wild swings of the stock market provided a chance to get rich. It reminded me of one of my favorite articles reviewed by Chance News. <br />
<br />
Seen From a Rut, the Lottery Is Essential<br />
The New York Times<br />
July 16, 1996<br />
<br />
To the Editor:<br />
<br />
<blockquote>Your July 14 Week in Review article on lottery advertising repeats stereotypes about lottery players' being poor and uneducated and swept up into a gambling addiction. No doubt many are. But Gov. George E. Pataki's statement that "it has always bothered me to hold up the prospect of instant riches" could also be recast as, "I want to take away the only prospect poor people have of getting out of their rut."<br><br><br />
<br />
Before lotteries, other options existed for people to improve their lives, and the barriers were not so high. Graduate education today is expensive; many professions require training as well as licensing, and investing in stocks requires substantial equity. Most people are not so brilliant that they can start an Apple computer company in their garages. So, playing the lottery becomes a good investment when no alternative is better.<br><br><br />
<br />
Lottery players know that the odds are stacked against them, but they don't have to spend a lot of money. Quite a few win regularly. Many who play Lotto or Take 5 use wheeling systems, which, contrary to statements by lottery officials, do increase the chances of winning. I know; I play Lotto and I've won everything except the jackpot, and I win several times a year.<br><br><br />
<br />
Yes, I have lost more than I've won. But in the tedious world I inhabit along with so many other New Yorkers, I've bought a fantasy. If I ever win the jackpot, I'll wave to you from Sutton Place.</blockquote><br />
<br />
JOHN P. RASH New York, July 14, 1996<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Wikipedia vandalism to U.S. Senators==<br />
<br />
A recent [http://digg.com/politics/McCain_raped_wife_Obama_a_nudist_and_Hillary_has_a_penis methodical study] of</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=6751Chance News 312008-01-12T02:01:34Z<p>Thekohser: /* The Unbreakable Wikipedia? */ Add image</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 are non-white, with Inter fielding, 19,<br> Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
* This issue has been covered in the BBC radio 4 series [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7078555.stm More or Less.]<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state. However, the problem is clearly growing:<br />
<br />
<center>http://www.mywikibiz.com/images/2/21/DamagedViews.jpg</center><br />
<br />
It is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our assessment is that the Minnesota study would have accepted a passage like this as completely "undamaged".<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
===Potential bias in the study===<br />
'''1. From the study:'''<br />
<blockquote><br />
''We assume that one serving of an article by a Wikipedia server is a reasonable proxy for one view of that article by a user.''</blockquote><br />
:'''Critique:'''<br />
Humans don't read the entire article every time they load one in their browser. [http://www.poynterextra.org/eyetrack2004/main.htm Studies have shown] that readers of web pages tend to focus most of their priority on the top-left portion of the page. Therefore, this study is giving equal weight to words that appear at the bottom of an article, even though there is disproportionate reader emphasis on the first paragraph or two of any Wikipedia article.<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to bury his content in the middle or toward the end of Wikipedia articles, though fewer people being served the article would actually read his content.<br />
<br><br><br />
'''2. From the study:'''<br />
<blockquote><br />
''A tempting proxy for article views is article edits. However, we found essentially no correlation between views and edits in the request logs.''</blockquote><br />
:'''Critique:'''<br />
Why was there "essentially no correlation"? Popular, often-viewed pages on Wikipedia (examples include the articles about [http://en.wikipedia.org/wiki/Wiki wiki], [http://en.wikipedia.org/wiki/Chris_Benoit Chris Benoit], [http://en.wikipedia.org/wiki/Ann_Coulter Ann Coulter], [http://en.wikipedia.org/wiki/List_of_sex_positions List of sex positions], and [http://en.wikipedia.org/wiki/Jeff_Hardy Jeff Hardy]) are frequently semi-protected (only registered users with 4 days of experience may modify the article) or fully-protected (only administrators may access the edit feature). In fact, the above articles have all appeared in Wikipedia's "10 most popular articles of the month" list, and all remain protected from free editing. Therefore, a very powerful ''inverse'' relationship between views and edits would exist for [http://tools.wikimedia.de/~leon/stats/wikicharts/index.php?ns=articles&limit=100&month=08%2F2006&wiki=enwiki Wikipedia's most popular pages]; which probably topples the otherwise intuitive correlation between article views and article edits. Are the study's authors cognizant of this?<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add his content to contentious, popular articles, just before they are "locked down" from further editing. A Wikipedia administrator would have the capacity to make substantial edits to an article just before himself locking down (or asking an admin colleague to lock down) the very same article.<br />
<br><br><br />
'''3. From the study:'''<br />
<blockquote><br />
''...if a contribution is viewed many times without being changed or deleted, it is likely to be <s>a</s> valuable.''</blockquote><br />
:'''Critique:'''<br />
Or, equally likely, the contribution is not being read critically, or even read at all. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add content that is wordy, boring, and dense. Prose that intimidates or sedates the reader would be so bland as to encourage skimming (rather than editing!), every time it is viewed.<br />
<br><br><br />
'''4. From the study:'''<br />
<blockquote><br />
''Our software does not track persistent words if text is "cut-and-pasted" from one article to another. If an editor moves a block of text from one article to another, PWVs after the move will be credited to the moving editor, not to the original editors.''</blockquote><br />
:'''Critique:'''<br />
Large credit goes, then, to "text movers" rather than "text creators". People who move a lot of text around will typically be busy-body administrators, rather than the careful scholars who painstakingly wrote the material in the first place. It is a known fact that the busiest administrators do a lot of "tidying" of major articles which lack any trace of their own content. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to become an administrator, then move a bunch of well-written content from article to article, which is frequently done among articles like "History of Tuscany" to "History of Italy" to "History of the Mediterranean" to "History of Europe" to the God-awful "History of western Eurasia".<br />
<br><br><br />
'''5. From the study:'''<br />
<blockquote><br />
''We exclude anonymous editors from some analyses, because IPs are not stable: multiple edits by the same human might be recorded under different IPs, and multiple humans can share an IP.''</blockquote><br />
:'''Critique:'''<br />
The same could be said for registered user accounts, which can be used from different IP addresses, by different people who know the password. It is a fact that some contributors to this very Chance News wiki are known to share registered Wikipedia user accounts. Regardless, the study itself found that anonymous IPs made 9 trillion edits out of a total of 34 trillion. Why would the study therefore exclude over 26% of the sample? This would have the effect of elevating the relative strength of contributions by a finite number of registered accounts, which is exactly what the study concludes. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to set up an account that he then shares with other like-minded individuals, so that more round-the-clock editing is possible, thereby building credibility in the community as a "dedicated Wikipedian". <br />
<br><br><br />
'''6. From the study:'''<br />
<blockquote><br />
''Reverts take two forms: '''identity revert''', where the post-revert revision is identical to a previous version, and '''effective revert''', where the effects of prior edits are removed (perhaps only partially), but the new text is not identical to any prior revision. ...In this paper, we consider only identity reverts.''</blockquote><br />
:'''Critique:'''<br />
Identity reverts, since they are a "button" tool that may seem intimidating to an average user, are probably more likely to be used by administrators, not scholars. Therefore, this study again gives extra strength to the actions of mop-wielding admins, rather than earnest shapers of Wikipedia. <br />
:'''Gaming the system:'''<br />
To count for more in this study, you wouldn't ever want to work to "improve" fixable recent content in Wikipedia. Rather, revert it, then re-write it in your own words.<br />
<br><br><br />
'''7. From the study:'''<br />
<blockquote><br />
''We believe it is reasonable to assume that essentially all damage is repaired within 15 revisions.''</blockquote><br />
:'''Critique:'''<br />
This may be so, but Figure 8 in the report also shows that 20% of the "Damaged-Loose" content incidents in Wikipedia are viewed by at least 30 people before they get fixed. Ten percent of such mistakes are viewed by well over 100 people before repaired. <br />
:'''Gaming the system:'''<br />
Learning to write mistaken or vandalistic prose in such a way that many, many people read it without "noticing" that it is wrong would be a way to further extend the time and views until detection. The libelous content written about [http://en.wikipedia.org/wiki/Seigenthaler_controversy John Seigenthaler, Sr.] and about [http://en.wikipedia.org/wiki/Fuzzy_Zoeller#Controversies Fuzzy Zoeller] went unnoticed for a number of weeks or months without causing any alarm. An effective way to make unsuspecting readers believe a lie in Wikipedia is to show a reference citation next to the false content. The reference need not even link to a source making the same claim you are making.<br />
<br />
==Rudy wrong on cancer survival chances==<br />
The [http://blog.washingtonpost.com/fact-checker/2007/10/rudy_miscalculates_cancer_surv.html ''Washington Post Fact Checker'', Oct. 30, 2007]<br><br />
Michael Dobbs<br />
<br />
This Blog describes its goal as follows:<br />
<br />
<blockquote>Our goal is to shed as much light as possible on controversial claims and counter-claims involving important national issues and the records of the various presidential candidates.</blockquote><br />
<br />
Here they discuss Giuliani’s New Hampshire radio advertisement, October 29, 2007.<br />
<br />
<blockquote>I had prostate cancer, five, six years ago. My chances of surviving prostate cancer and thank God I was cured of it, in the United States, 82 percent. My chances of surviving prostate cancer in England, only 44 percent under socialized medicine.</blockquote><br />
<br />
It is not clear what is being compared here. It is probably meant to be the survival rate. This is defined by the National Cancer Institution as: <br />
<br />
<blockquote>The percentage of people in a study or treatment group who are alive for a given period of time after diagnosis. This is commonly expressed as 5-year survival.</blockquote><br />
<br />
The Giuliani campaign reports that these percentages came from an article in [http://www.city-journal.org/html/17_3_canadian_healthcare.html ''City Journal''], a publication of the Manhattan Institute, a conservative research organization. This article, ''The Ugly Truth About Canadian Health Care'', was written by Dr. Lavid Gratzer, a senior fellow at the Manhattan Institute and an adviser for the Giuliani campaign. While the article did not say where the numbers came from, Dr. Gratzer has now explained that they came from a Commonwealth Fund article<br />
''Multination Comparisons of Health Systems Data, 2000'' by Gerard F. Anderson and Peter S. Hussey of Johns Hopkins University. Specifically they came from this graphic in the Commenwealth Fund article:<br />
<br />
<center> http://www.dartmouth.edu/~chance/forwiki/prostate.jpg</center><br />
<br />
The Commonweath Fund provided a [http://www.commonwealthfund.org/newsroom/newsroom_show.htm?doc_id=568333 a Statement] in repsonse to Giuliani’s advertisement. They say:<br />
<br />
<blockquote>The incidence rates simply report the number of men diagnosed with prostate cancer in a given year. Prostate cancer mortality rates report the number of men who died of the disease in a given year. Neither speaks to length of survival, and that figure can not be calculated using the others. </blockquote> <br />
<br />
But Dr. Gratzer defends Guiliani's ad in an article "On cancer survival rates, Rudy’s right and his critics are wrong" ''City Journal'', 31 October 2007. Here we read: <br />
<br />
<blockquote>Let me be very clear about why the Giuliani campaign is correct: the percentage of people diagnosed with prostate cancer who die from it is much higher in Britain than in the United States. The Organization for Economic Co-operation and Development reports on both the incidence of prostate cancer in member nations and the number of resultant deaths. According to OECD data published in 2000, 49 Britons per 100,000 were diagnosed with prostate cancer, and 28 per 100,000 died of it. This means that 57 percent of Britons diagnosed with prostate cancer died of it; and, consequently, that just 43 percent survived.</blockquote><br />
<br />
Finally, from the Washington Post Blog we read:<br />
<br />
<blockquote>UPDATE: Maria Comella, deputy communications manager for the Giuliani campaign, sent us the following e-mail explaining the mayor's mistake without quite acknowledging it: <blockquote>Mayor Giuliani is an avid reader of ''City Journal'' and found the passage in the Gratzer article himself. He cited the statistics at a campaign stop, and the campaign used a recording from that appearance in the radio ad. The citation is an article in a highy respected intellectual journal written by an expert at a highly respected think tank which the mayor read because he is an intellectually engaged human being.</blockquote><br />
<br />
===Discussion===<br />
<br />
(1) Do you agree with the Commonwealth Fund statement?<br />
<br />
(2) Do you agree with Gretzer's explanation?<br />
<br />
(3) Others say that the difference is caused by the fact that the United States screens for Prostate Cancer earlier than England does so of course the survival rate will be longer. Is this relevant to this controversy?<br />
<br />
==More or less==<br />
[http://www.ft.com/cms/s/0/52e30ae6-9191-11dc-9590-0000779fd2ac.html Lunch with the FT: Andrew Dilnot,] by Tim Harford, The Financial Times, 16 Nov 2007.<br />
<br />
Chance readers may be interested in a BBC Radio 4 series called [http://news.bbc.co.uk/1/hi/programmes/more_or_less/ <em>More or less</em>,] which is about numbers in the news.<br />
(The original presenter [http://en.wikipedia.org/wiki/Andrew_Dilnot Andrew Dilnot] recently <br />
[http://www.ft.com/cms/s/0/52e30ae6-9191-11dc-9590-0000779fd2ac.html stepped down]<br />
to be replaced by [http://www.timharford.com/ Tim Hartford,] <br />
who writes the 'Dear Economist' column for the Financial Times.)<br />
<br />
The website for the programme gives a hint at the topics covered:<br />
* [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7101633.stm predicting bird flu]<br />
* [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7090524.stm measuring happiness]<br />
* [http://news.bbc.co.uk/1/hi/programmes/more_or_less/7078555.stm migrant figures that do not add up] (covered in a Chance news article in this issue)<br />
* [http://open2.net/sciencetechnologynature/maths/coincidence.html The dangers of spotting patterns in random things]<br />
<br />
Dilnot says that in the radio show<br />
<blockquote><br />
We are trying to show people how they can interpret the numbers that are thrown at them.<br />
</blockquote><br />
He advises people to ask simple questions, such as: <em>Is that a big number?</em><br />
In the interview by Harford, Dilnot claims that <br />
the worst social statistic of all time was that <br />
<em>the number of children killed in the United States has doubled every year since 1953</em>.<br />
<br />
One simple trick is to try to humanize statistics, Dilnot claims:<br />
<blockquote><br />
Faced with a question such as: <em>how many petrol (gasoline in the US) stations are there in the UK?</em>, ask yourself how many petrol stations there are in your town, and how many people. It’s the first step towards grasping a sensible answer to the bigger question.<br />
</blockquote><br />
<br />
Dilnot has written that just about the only question that can’t be partially answered with reference to personal experience is: <em>how many penguins are there in Antarctica?</em> due to the difficulties of a credible penguin census.<br />
<br />
===Questions===<br />
* What is wrong with the claim that <em>the number of children killed in the United States has doubled every year since 1953</em>? <br />
* What is your estimate of how many penguins there are in Antarctica? What bounds do you wish to put around your estimate?<br />
<br />
===Further reading===<br />
* More or Less can be heard on Mondays on BBC Radio 4 at 16:30 BST and is presented by Tim Harford.<br />
** More or Less is a permanent part of the schedule with two series annually, one in the summer, one in winter. <br />
** Here is a link to [http://www.bbc.co.uk/radio/aod/mainframe.shtml?http://www.bbc.co.uk/radio/aod/radio4_aod.shtml?radio4/moreorless the most recent version].<br />
** Since January 2005, it has been produced in association with [http://www.open2.net/moreorless/ the Open University,] who provide links to related webpages, such as: [http://open2.net/sciencetechnologynature/maths/statisticsmedia.html Statistics and the media] and [http://open2.net/sciencetechnologynature/maths/statistics.html Guide to statistics.]<br />
* [http://plus.maths.org/issue45/features/tiger/index.html The Tiger That Isn’t,] Andrew Dilnot's recent book covering similar topics to the radio show.<br />
** Plus Magazine offer a [http://plus.maths.org/issue45/reviews/book2/ review of this book.]<br />
* [http://www.amazon.co.uk/Undercover-Economist-Tim-Harford/dp/0316732931 The Undercover Economist,] a recent book by the new presenter, Tim Harford.<br />
<br />
Submitted by John Gavin.<br />
<br />
==Name-Letter-Effect==<br />
An article in Psychological Science, Volume 18 Issue 12 Page 1106-1112, December 2007 by Nelson and Simmons has received much attention in the lay press, including, Sports Illustrated, Newsweek and USA Today. From the abstract of the article: "we found that people like their names enough to unconsciously pursue consciously avoided outcomes that resemble their names." In other words, as USA Today put it in its headline, "My name made me do it." Put another way, instead of astrology with its alignment of the stars at birth causing your success or failure, it is the name given to you that predicts behavior.<br />
<br />
The article discusses five studies. The "it" in the first study refers to Major League Baseball players who have an initial "K"-the symbol for recording strikeouts--strike out more often, 18.8%, than players with other initials, 17.2%. This study looked at 6397 players who had at least 100 at bats. A hypothesis test was performed and the authors state that "t(6395) = 3.08," yielding a p-value of ".002." However, using the same database, a [http://sabermetricresearch.blogspot.com Blogger] found otherwise; in particular, for 1960s to 2000s: Ks 14.5%, non-Ks 14.2%. This blogger concludes with, "So the big question remains: why did the authors get such a high strikeout rate difference?"<br />
<br />
Here is why: Nelson and Simmons did not do the customary hypothesis test of difference in proportions but instead did a hypothesis test of the difference in means. That is, a batter's strikeout to at bat ratio was not weighted by the number of at bats.<br />
<br />
The "it" in the second study refers to MBA academic performance at an unnamed institution. Looking at about 15,000 students, "As predicted, students whose names begin with a C or D earned lower GPAs than students whose names begin with A or B, F(4, 14348) = 4.55" yielding a p-value of ".001." The effect size is teeny and somehow, those whose initials are E through Z actually have the highest average GPAs.<br />
<br />
===Discussion===<br />
<br />
1. Baseball is full of slang. Two common terms for striking out are "fanning" and "whiffing." Obtain [http://www.baseball-databank.org/ the data set] and do a test for F or W to see what p-value ensues.<br />
<br />
2. The figure below is Fig. 1 in the original paper where the GPAs of A, B, C, D, and Other are displayed. Why is the graph misleading?<br />
<br />
<center> http://www.dartmouth.edu/~chance/forwiki/Figure1.jpg</center><br />
<br />
<center>Fig. 1. Results of Study 2: grade point average <br><br />
as a function of the student's initial. Error bars in...</center><br />
<br />
3. The "it" in a third study looks at 492,458 lawyers at 170 law schools. The dependent variable is law-school quality which varies from Tier 1 (best), Tier 2, Tier 3, Tier 4 (worst). The independent variable is "the proportion of lawyers with initials A and B (relative to lawyers with initials C and D)." The regression result was a slope of -.17 yielding a p-value of .036. The authors conclude, "It seems that people with names like Adlai and Bill tend to go to better law schools that do those with names like Chester and Dwight." Comment on the qualitative nature of the dependent variable and how regression might be affected. Comment on Bill.<br />
<br />
4. The Newsweek writer notes that "the GPA gap is tiny-3.34 versus 3.36." She then claims, "But there is a saying in science that if you discover a way to levitate objects with your thoughts by one millimeter, you don't focus on the millimeter-the size of the effect-but on the fact that something happened at all." Defend and criticize her statement.<br />
<br />
Submitted by Paul Alper</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=User:Thekohser&diff=13120User:Thekohser2007-11-10T06:05:19Z<p>Thekohser: Corrections</p>
<hr />
<div>I am a practitioner in marketing research at [http://www.comcast.com Comcast Corporation]. I write a blog about my industry, though it frequently goes off-topic. It's called [http://insidemr.blogspot.com Inside Market Research]. I am co-developing a wiki directory called [http://www.centiare.com Centiare].</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4719Chance News 312007-11-10T06:03:57Z<p>Thekohser: /* Potential bias in the study */ spelling</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 or non-white, with Inter Fielding, 19, Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
It is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our assessment is that the Minnesota study would have accepted a passage like this as completely "undamaged".<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
===Potential bias in the study===<br />
'''1. From the study:'''<br />
<blockquote><br />
''We assume that one serving of an article by a Wikipedia server is a reasonable proxy for one view of that article by a user.''</blockquote><br />
:'''Critique:'''<br />
Humans don't read the entire article every time they load one in their browser. [http://www.poynterextra.org/eyetrack2004/main.htm Studies have shown] that readers of web pages tend to focus most of their priority on the top-left portion of the page. Therefore, this study is giving equal weight to words that appear at the bottom of an article, even though there is disproportionate reader emphasis on the first paragraph or two of any Wikipedia article.<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to bury his content in the middle or toward the end of Wikipedia articles, though fewer people being served the article would actually read his content.<br />
<br><br><br />
'''2. From the study:'''<br />
<blockquote><br />
''A tempting proxy for article views is article edits. However, we found essentially no correlation between views and edits in the request logs.''</blockquote><br />
:'''Critique:'''<br />
Why was there "essentially no correlation"? Popular, often-viewed pages on Wikipedia (examples include the articles about [http://en.wikipedia.org/wiki/Wiki wiki], [http://en.wikipedia.org/wiki/Chris_Benoit Chris Benoit], [http://en.wikipedia.org/wiki/Ann_Coulter Ann Coulter], [http://en.wikipedia.org/wiki/List_of_sex_positions List of sex positions], and [http://en.wikipedia.org/wiki/Jeff_Hardy Jeff Hardy]) are frequently semi-protected (only registered users with 4 days of experience may modify the article) or fully-protected (only administrators may access the edit feature). In fact, the above articles have all appeared in Wikipedia's "10 most popular articles of the month" list, and all remain protected from free editing. Therefore, a very powerful ''inverse'' relationship between views and edits would exist for [http://tools.wikimedia.de/~leon/stats/wikicharts/index.php?ns=articles&limit=100&month=08%2F2006&wiki=enwiki Wikipedia's most popular pages]; which probably topples the otherwise intuitive correlation between article views and article edits. Are the study's authors cognizant of this?<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add his content to contentious, popular articles, just before they are "locked down" from further editing. A Wikipedia administrator would have the capacity to make substantial edits to an article just before himself locking down (or asking an admin colleague to lock down) the very same article.<br />
<br><br><br />
'''3. From the study:'''<br />
<blockquote><br />
''...if a contribution is viewed many times without being changed or deleted, it is likely to be <s>a</s> valuable.''</blockquote><br />
:'''Critique:'''<br />
Or, equally likely, the contribution is not being read critically, or even read at all. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add content that is wordy, boring, and dense. Prose that intimidates or sedates the reader would be so bland as to encourage skimming (rather than editing!), every time it is viewed.<br />
<br><br><br />
'''4. From the study:'''<br />
<blockquote><br />
''Our software does not track persistent words if text is "cut-and-pasted" from one article to another. If an editor moves a block of text from one article to another, PWVs after the move will be credited to the moving editor, not to the original editors.''</blockquote><br />
:'''Critique:'''<br />
Large credit goes, then, to "text movers" rather than "text creators". People who move a lot of text around will typically be busy-body administrators, rather than the careful scholars who painstakingly wrote the material in the first place. It is a known fact that the busiest administrators do a lot of "tidying" of major articles which lack any trace of their own content. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to become an administrator, then move a bunch of well-written content from article to article, which is frequently done among articles like "History of Tuscany" to "History of Italy" to "History of the Mediterranean" to "History of Europe" to the God-awful "History of western Eurasia".<br />
<br><br><br />
'''5. From the study:'''<br />
<blockquote><br />
''We exclude anonymous editors from some analyses, because IPs are not stable: multiple edits by the same human might be recorded under different IPs, and multiple humans can share an IP.''</blockquote><br />
:'''Critique:'''<br />
The same could be said for registered user accounts, which can be used from different IP addresses, by different people who know the password. It is a fact that some contributors to this very Chance News wiki are known to share registered Wikipedia user accounts. Regardless, the study itself found that anonymous IPs made 9 trillion edits out of a total of 34 trillion. Why would the study therefore exclude over 26% of the sample? This would have the effect of elevating the relative strength of contributions by a finite number of registered accounts, which is exactly what the study concludes. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to set up an account that he then shares with other like-minded individuals, so that more round-the-clock editing is possible, thereby building credibility in the community as a "dedicated Wikipedian". <br />
<br><br><br />
'''6. From the study:'''<br />
<blockquote><br />
''Reverts take two forms: '''identity revert''', where the post-revert revision is identical to a previous version, and '''effective revert''', where the effects of prior edits are removed (perhaps only partially), but the new text is not identical to any prior revision. ...In this paper, we consider only identity reverts.''</blockquote><br />
:'''Critique:'''<br />
Identity reverts, since they are a "button" tool that may seem intimidating to an average user, are probably more likely to be used by administrators, not scholars. Therefore, this study again gives extra strength to the actions of mop-wielding admins, rather than earnest shapers of Wikipedia. <br />
:'''Gaming the system:'''<br />
To count for more in this study, you wouldn't ever want to work to "improve" fixable recent content in Wikipedia. Rather, revert it, then re-write it in your own words.<br />
<br><br><br />
'''7. From the study:'''<br />
<blockquote><br />
''We believe it is reasonable to assume that essentially all damage is repaired within 15 revisions.''</blockquote><br />
:'''Critique:'''<br />
This may be so, but Figure 8 in the report also shows that 20% of the "Damaged-Loose" content incidents in Wikipedia are viewed by at least 30 people before they get fixed. Ten percent of such mistakes are viewed by well over 100 people before repaired. <br />
:'''Gaming the system:'''<br />
Learning to write mistaken or vandalistic prose in such a way that many, many people read it without "noticing" that it is wrong would be a way to further extend the time and views until detection. The libelous content written about [http://en.wikipedia.org/wiki/Seigenthaler_controversy John Seigenthaler, Sr.] and about [http://en.wikipedia.org/wiki/Fuzzy_Zoeller#Controversies Fuzzy Zoeller] went unnoticed for a number of weeks or months without causing any alarm. An effective way to make unsuspecting readers believe a lie in Wikipedia is to show a reference citation next to the false content. The reference need not even link to a source making the same claim you are making.<br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4717Chance News 312007-11-10T04:53:11Z<p>Thekohser: /* The Unbreakable Wikipedia? */ Add line breaks</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 or non-white, with Inter Fielding, 19, Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
It is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our assessment is that the Minnesota study would have accepted a passage like this as completely "undamaged".<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
===Potential bias in the study===<br />
'''1. From the study:'''<br />
<blockquote><br />
''We assume that one serving of an article by a Wikipedia server is a reasonable proxy for one view of that article by a user.''</blockquote><br />
:'''Critique:'''<br />
Humans don't read the entire article every time they load one in their browser. [http://www.poynterextra.org/eyetrack2004/main.htm Studies have shown] that readers of web pages tend to focus most of their priority on the top-left portion of the page. Therefore, this study is giving equal weight to words that appear at the bottom of an article, even though there is disproportionate reader emphasis on the first paragraph or two of any Wikipedia article.<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to bury his content in the middle or toward the end of Wikipedia articles, though fewer people being served the article would actually read his content.<br />
<br><br><br />
'''2. From the study:'''<br />
<blockquote><br />
''A tempting proxy for article views is article edits. However, we found essentially no correlation between views and edits in the request logs.''</blockquote><br />
:'''Critique:'''<br />
Why was there "essentially no correlation"? Popular, often-viewed pages on Wikipedia (examples include the articles about [http://en.wikipedia.org/wiki/Wiki wiki], [http://en.wikipedia.org/wiki/Chris_Benoit Chris Benoit], [http://en.wikipedia.org/wiki/Ann_Coulter Ann Coulter], [http://en.wikipedia.org/wiki/List_of_sex_positions List of sex positions], and [http://en.wikipedia.org/wiki/Jeff_Hardy Jeff Hardy]) are frequently semi-protected (only registered users with 4 days of experience may modify the article) or fully-protected (only administrators my access the edit feature). In fact, the above articles have all appeared in Wikipedia's "10 most popular articles of the month" list, and all remain protected from free editing. Therefore, a very powerful ''inverse'' relationship between views and edits would exist for [http://tools.wikimedia.de/~leon/stats/wikicharts/index.php?ns=articles&limit=100&month=08%2F2006&wiki=enwiki Wikipedia's most popular pages]; which probably topples the otherwise intuitive correlation between article views and article edits. Are the study's authors cognizant of this?<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add his content to contentious, popular articles, just before they are "locked down" from further editing. A Wikipedia administrator would have the capacity to make substantial edits to an article just before himself locking down (or asking an admin colleague to lock down) the very same article.<br />
<br><br><br />
'''3. From the study:'''<br />
<blockquote><br />
''...if a contribution is viewed many times without being changed or deleted, it is likely to be <s>a</s> valuable.''</blockquote><br />
:'''Critique:'''<br />
Or, equally likely, the contribution is not being read critically, or even read at all. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add content that is wordy, boring, and dense. Prose that intimidates or sedates the reader would be so bland as to encourage skimming (rather than editing!), every time it is viewed.<br />
<br><br><br />
'''4. From the study:'''<br />
<blockquote><br />
''Our software does not track persistent words if text is "cut-and-pasted" from one article to another. If an editor moves a block of text from one article to another, PWVs after the move will be credited to the moving editor, not to the original editors.''</blockquote><br />
:'''Critique:'''<br />
Large credit goes, then, to "text movers" rather than "text creators". People who move a lot of text around will typically be busy-body administrators, rather than the careful scholars who painstakingly wrote the material in the first place. It is a known fact that the busiest administrators do a lot of "tidying" of major articles which lack any trace of their own content. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to become an administrator, then move a bunch of well-written content from article to article, which is frequently done among articles like "History of Tuscany" to "History of Italy" to "History of the Mediterranean" to "History of Europe" to the God-awful "History of western Eurasia".<br />
<br><br><br />
'''5. From the study:'''<br />
<blockquote><br />
''We exclude anonymous editors from some analyses, because IPs are not stable: multiple edits by the same human might be recorded under different IPs, and multiple humans can share an IP.''</blockquote><br />
:'''Critique:'''<br />
The same could be said for registered user accounts, which can be used from different IP addresses, by different people who know the password. It is a fact that some contributors to this very Chance News wiki are known to share registered Wikipedia user accounts. Regardless, the study itself found that anonymous IPs made 9 trillion edits out of a total of 34 trillion. Why would the study therefore exclude over 26% of the sample? This would have the effect of elevating the relative strength of contributions by a finite number of registered accounts, which is exactly what the study concludes. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to set up an account that he then shares with other like-minded individuals, so that more round-the-clock editing is possible, thereby building credibility in the community as a "dedicated Wikipedian". <br />
<br><br><br />
'''6. From the study:'''<br />
<blockquote><br />
''Reverts take two forms: '''identity revert''', where the post-revert revision is identical to a previous version, and '''effective revert''', where the effects of prior edits are removed (perhaps only partially), but the new text is not identical to any prior revision. ...In this paper, we consider only identity reverts.''</blockquote><br />
:'''Critique:'''<br />
Identity reverts, since they are a "button" tool that may seem intimidating to an average user, are probably more likely to be used by administrators, not scholars. Therefore, this study again gives extra strength to the actions of mop-wielding admins, rather than earnest shapers of Wikipedia. <br />
:'''Gaming the system:'''<br />
To count for more in this study, you wouldn't ever want to work to "improve" fixable recent content in Wikipedia. Rather, revert it, then re-write it in your own words.<br />
<br><br><br />
'''7. From the study:'''<br />
<blockquote><br />
''We believe it is reasonable to assume that essentially all damage is repaired within 15 revisions.''</blockquote><br />
:'''Critique:'''<br />
This may be so, but Figure 8 in the report also shows that 20% of the "Damaged-Loose" content incidents in Wikipedia are viewed by at least 30 people before they get fixed. Ten percent of such mistakes are viewed by well over 100 people before repaired. <br />
:'''Gaming the system:'''<br />
Learning to write mistaken or vandalistic prose in such a way that many, many people read it without "noticing" that it is wrong would be a way to further extend the time and views until detection. The libelous content written about [http://en.wikipedia.org/wiki/Seigenthaler_controversy John Seigenthaler, Sr.] and about [http://en.wikipedia.org/wiki/Fuzzy_Zoeller#Controversies Fuzzy Zoeller] went unnoticed for a number of weeks or months without causing any alarm. An effective way to make unsuspecting readers believe a lie in Wikipedia is to show a reference citation next to the false content. The reference need not even link to a source making the same claim you are making.<br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4716Chance News 312007-11-10T04:50:43Z<p>Thekohser: /* Potential bias in the study */ Fixing list of popular pages with actual blocked examples.</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 or non-white, with Inter Fielding, 19, Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
It is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our assessment is that the Minnesota study would have accepted a passage like this as completely "undamaged".<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
===Potential bias in the study===<br />
'''1. From the study:'''<br />
<blockquote><br />
''We assume that one serving of an article by a Wikipedia server is a reasonable proxy for one view of that article by a user.''</blockquote><br />
:'''Critique:'''<br />
Humans don't read the entire article every time they load one in their browser. [http://www.poynterextra.org/eyetrack2004/main.htm Studies have shown] that readers of web pages tend to focus most of their priority on the top-left portion of the page. Therefore, this study is giving equal weight to words that appear at the bottom of an article, even though there is disproportionate reader emphasis on the first paragraph or two of any Wikipedia article.<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to bury his content in the middle or toward the end of Wikipedia articles, though fewer people being served the article would actually read his content.<br />
<br><br />
'''2. From the study:'''<br />
<blockquote><br />
''A tempting proxy for article views is article edits. However, we found essentially no correlation between views and edits in the request logs.''</blockquote><br />
:'''Critique:'''<br />
Why was there "essentially no correlation"? Popular, often-viewed pages on Wikipedia (examples include the articles about [http://en.wikipedia.org/wiki/Wiki wiki], [http://en.wikipedia.org/wiki/Chris_Benoit Chris Benoit], [http://en.wikipedia.org/wiki/Ann_Coulter Ann Coulter], [http://en.wikipedia.org/wiki/List_of_sex_positions List of sex positions], and [http://en.wikipedia.org/wiki/Jeff_Hardy Jeff Hardy]) are frequently semi-protected (only registered users with 4 days of experience may modify the article) or fully-protected (only administrators my access the edit feature). In fact, the above articles have all appeared in Wikipedia's "10 most popular articles of the month" list, and all remain protected from free editing. Therefore, a very powerful ''inverse'' relationship between views and edits would exist for [http://tools.wikimedia.de/~leon/stats/wikicharts/index.php?ns=articles&limit=100&month=08%2F2006&wiki=enwiki Wikipedia's most popular pages]; which probably topples the otherwise intuitive correlation between article views and article edits. Are the study's authors cognizant of this?<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add his content to contentious, popular articles, just before they are "locked down" from further editing. A Wikipedia administrator would have the capacity to make substantial edits to an article just before himself locking down (or asking an admin colleague to lock down) the very same article.<br />
<br><br />
'''3. From the study:'''<br />
<blockquote><br />
''...if a contribution is viewed many times without being changed or deleted, it is likely to be <s>a</s> valuable.''</blockquote><br />
:'''Critique:'''<br />
Or, equally likely, the contribution is not being read critically, or even read at all. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add content that is wordy, boring, and dense. Prose that intimidates or sedates the reader would be so bland as to encourage skimming (rather than editing!), every time it is viewed.<br />
<br><br />
'''4. From the study:'''<br />
<blockquote><br />
''Our software does not track persistent words if text is "cut-and-pasted" from one article to another. If an editor moves a block of text from one article to another, PWVs after the move will be credited to the moving editor, not to the original editors.''</blockquote><br />
:'''Critique:'''<br />
Large credit goes, then, to "text movers" rather than "text creators". People who move a lot of text around will typically be busy-body administrators, rather than the careful scholars who painstakingly wrote the material in the first place. It is a known fact that the busiest administrators do a lot of "tidying" of major articles which lack any trace of their own content. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to become an administrator, then move a bunch of well-written content from article to article, which is frequently done among articles like "History of Tuscany" to "History of Italy" to "History of the Mediterranean" to "History of Europe" to the God-awful "History of western Eurasia".<br />
<br><br />
'''5. From the study:'''<br />
<blockquote><br />
''We exclude anonymous editors from some analyses, because IPs are not stable: multiple edits by the same human might be recorded under different IPs, and multiple humans can share an IP.''</blockquote><br />
:'''Critique:'''<br />
The same could be said for registered user accounts, which can be used from different IP addresses, by different people who know the password. It is a fact that some contributors to this very Chance News wiki are known to share registered Wikipedia user accounts. Regardless, the study itself found that anonymous IPs made 9 trillion edits out of a total of 34 trillion. Why would the study therefore exclude over 26% of the sample? This would have the effect of elevating the relative strength of contributions by a finite number of registered accounts, which is exactly what the study concludes. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to set up an account that he then shares with other like-minded individuals, so that more round-the-clock editing is possible, thereby building credibility in the community as a "dedicated Wikipedian". <br />
<br><br />
'''6. From the study:'''<br />
<blockquote><br />
''Reverts take two forms: '''identity revert''', where the post-revert revision is identical to a previous version, and '''effective revert''', where the effects of prior edits are removed (perhaps only partially), but the new text is not identical to any prior revision. ...In this paper, we consider only identity reverts.''</blockquote><br />
:'''Critique:'''<br />
Identity reverts, since they are a "button" tool that may seem intimidating to an average user, are probably more likely to be used by administrators, not scholars. Therefore, this study again gives extra strength to the actions of mop-wielding admins, rather than earnest shapers of Wikipedia. <br />
:'''Gaming the system:'''<br />
To count for more in this study, you wouldn't ever want to work to "improve" fixable recent content in Wikipedia. Rather, revert it, then re-write it in your own words.<br />
<br><br />
'''7. From the study:'''<br />
<blockquote><br />
''We believe it is reasonable to assume that essentially all damage is repaired within 15 revisions.''</blockquote><br />
:'''Critique:'''<br />
This may be so, but Figure 8 in the report also shows that 20% of the "Damaged-Loose" content incidents in Wikipedia are viewed by at least 30 people before they get fixed. Ten percent of such mistakes are viewed by well over 100 people before repaired. <br />
:'''Gaming the system:'''<br />
Learning to write mistaken or vandalistic prose in such a way that many, many people read it without "noticing" that it is wrong would be a way to further extend the time and views until detection. The libelous content written about [http://en.wikipedia.org/wiki/Seigenthaler_controversy John Seigenthaler, Sr.] and about [http://en.wikipedia.org/wiki/Fuzzy_Zoeller#Controversies Fuzzy Zoeller] went unnoticed for a number of weeks or months without causing any alarm. An effective way to make unsuspecting readers believe a lie in Wikipedia is to show a reference citation next to the false content. The reference need not even link to a source making the same claim you are making.<br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4715Chance News 312007-11-10T04:28:14Z<p>Thekohser: /* The Unbreakable Wikipedia? */ Seems like we're not in "proposal" stage any more.</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 or non-white, with Inter Fielding, 19, Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
It is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our assessment is that the Minnesota study would have accepted a passage like this as completely "undamaged".<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
===Potential bias in the study===<br />
'''1. From the study:'''<br />
<blockquote><br />
''We assume that one serving of an article by a Wikipedia server is a reasonable proxy for one view of that article by a user.''</blockquote><br />
:'''Critique:'''<br />
Humans don't read the entire article every time they load one in their browser. [http://www.poynterextra.org/eyetrack2004/main.htm Studies have shown] that readers of web pages tend to focus most of their priority on the top-left portion of the page. Therefore, this study is giving equal weight to words that appear at the bottom of an article, even though there is disproportionate reader emphasis on the first paragraph or two of any Wikipedia article.<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to bury his content in the middle or toward the end of Wikipedia articles, though fewer people being served the article would actually read his content.<br />
<br><br />
'''2. From the study:'''<br />
<blockquote><br />
''A tempting proxy for article views is article edits. However, we found essentially no correlation between views and edits in the request logs.''</blockquote><br />
:'''Critique:'''<br />
Why was there "essentially no correlation"? Popular, often-viewed pages on Wikipedia (examples may include George W. Bush, Barack Obama, evolution, and list of big-bust models and performers) are frequently semi-protected (only registered users with 4 days of tenure may modify the article) or fully-protected (only administrators my access the edit feature). Therefore, a powerful ''inverse'' relationship between views and edits would exist for those pages; quite possibly throwing off the otherwise intuitive correlation between article views and article edits. Were the study's authors cognizant of this?<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add his content to contentious, popular articles, just before they are "locked down" from further editing. A Wikipedia administrator would have the capacity to make substantial edits to an article just before himself locking down (or asking an admin colleague to lock down) the very same article.<br />
<br><br />
'''3. From the study:'''<br />
<blockquote><br />
''...if a contribution is viewed many times without being changed or deleted, it is likely to be <s>a</s> valuable.''</blockquote><br />
:'''Critique:'''<br />
Or, equally likely, the contribution is not being read critically, or even read at all. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add content that is wordy, boring, and dense. Prose that intimidates or sedates the reader would be so bland as to encourage skimming (rather than editing!), every time it is viewed.<br />
<br><br />
'''4. From the study:'''<br />
<blockquote><br />
''Our software does not track persistent words if text is "cut-and-pasted" from one article to another. If an editor moves a block of text from one article to another, PWVs after the move will be credited to the moving editor, not to the original editors.''</blockquote><br />
:'''Critique:'''<br />
Large credit goes, then, to "text movers" rather than "text creators". People who move a lot of text around will typically be busy-body administrators, rather than the careful scholars who painstakingly wrote the material in the first place. It is a known fact that the busiest administrators do a lot of "tidying" of major articles which lack any trace of their own content. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to become an administrator, then move a bunch of well-written content from article to article, which is frequently done among articles like "History of Tuscany" to "History of Italy" to "History of the Mediterranean" to "History of Europe" to the God-awful "History of western Eurasia".<br />
<br><br />
'''5. From the study:'''<br />
<blockquote><br />
''We exclude anonymous editors from some analyses, because IPs are not stable: multiple edits by the same human might be recorded under different IPs, and multiple humans can share an IP.''</blockquote><br />
:'''Critique:'''<br />
The same could be said for registered user accounts, which can be used from different IP addresses, by different people who know the password. It is a fact that some contributors to this very Chance News wiki are known to share registered Wikipedia user accounts. Regardless, the study itself found that anonymous IPs made 9 trillion edits out of a total of 34 trillion. Why would the study therefore exclude over 26% of the sample? This would have the effect of elevating the relative strength of contributions by a finite number of registered accounts, which is exactly what the study concludes. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to set up an account that he then shares with other like-minded individuals, so that more round-the-clock editing is possible, thereby building credibility in the community as a "dedicated Wikipedian". <br />
<br><br />
'''6. From the study:'''<br />
<blockquote><br />
''Reverts take two forms: '''identity revert''', where the post-revert revision is identical to a previous version, and '''effective revert''', where the effects of prior edits are removed (perhaps only partially), but the new text is not identical to any prior revision. ...In this paper, we consider only identity reverts.''</blockquote><br />
:'''Critique:'''<br />
Identity reverts, since they are a "button" tool that may seem intimidating to an average user, are probably more likely to be used by administrators, not scholars. Therefore, this study again gives extra strength to the actions of mop-wielding admins, rather than earnest shapers of Wikipedia. <br />
:'''Gaming the system:'''<br />
To count for more in this study, you wouldn't ever want to work to "improve" fixable recent content in Wikipedia. Rather, revert it, then re-write it in your own words.<br />
<br><br />
'''7. From the study:'''<br />
<blockquote><br />
''We believe it is reasonable to assume that essentially all damage is repaired within 15 revisions.''</blockquote><br />
:'''Critique:'''<br />
This may be so, but Figure 8 in the report also shows that 20% of the "Damaged-Loose" content incidents in Wikipedia are viewed by at least 30 people before they get fixed. Ten percent of such mistakes are viewed by well over 100 people before repaired. <br />
:'''Gaming the system:'''<br />
Learning to write mistaken or vandalistic prose in such a way that many, many people read it without "noticing" that it is wrong would be a way to further extend the time and views until detection. The libelous content written about [http://en.wikipedia.org/wiki/Seigenthaler_controversy John Seigenthaler, Sr.] and about [http://en.wikipedia.org/wiki/Fuzzy_Zoeller#Controversies Fuzzy Zoeller] went unnoticed for a number of weeks or months without causing any alarm. An effective way to make unsuspecting readers believe a lie in Wikipedia is to show a reference citation next to the false content. The reference need not even link to a source making the same claim you are making.<br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4714Chance News 312007-11-10T04:23:36Z<p>Thekohser: /* Potential bias in the study */ Numbering</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 or non-white, with Inter Fielding, 19, Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
(This submission to Chance News 31 will be expanded, but it is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our guess is that the Minnesota study would have accepted a passage like this as "undamaged", but we still need to read the white paper itself.)<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
===Potential bias in the study===<br />
'''1. From the study:'''<br />
<blockquote><br />
''We assume that one serving of an article by a Wikipedia server is a reasonable proxy for one view of that article by a user.''</blockquote><br />
:'''Critique:'''<br />
Humans don't read the entire article every time they load one in their browser. [http://www.poynterextra.org/eyetrack2004/main.htm Studies have shown] that readers of web pages tend to focus most of their priority on the top-left portion of the page. Therefore, this study is giving equal weight to words that appear at the bottom of an article, even though there is disproportionate reader emphasis on the first paragraph or two of any Wikipedia article.<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to bury his content in the middle or toward the end of Wikipedia articles, though fewer people being served the article would actually read his content.<br />
<br><br />
'''2. From the study:'''<br />
<blockquote><br />
''A tempting proxy for article views is article edits. However, we found essentially no correlation between views and edits in the request logs.''</blockquote><br />
:'''Critique:'''<br />
Why was there "essentially no correlation"? Popular, often-viewed pages on Wikipedia (examples may include George W. Bush, Barack Obama, evolution, and list of big-bust models and performers) are frequently semi-protected (only registered users with 4 days of tenure may modify the article) or fully-protected (only administrators my access the edit feature). Therefore, a powerful ''inverse'' relationship between views and edits would exist for those pages; quite possibly throwing off the otherwise intuitive correlation between article views and article edits. Were the study's authors cognizant of this?<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add his content to contentious, popular articles, just before they are "locked down" from further editing. A Wikipedia administrator would have the capacity to make substantial edits to an article just before himself locking down (or asking an admin colleague to lock down) the very same article.<br />
<br><br />
'''3. From the study:'''<br />
<blockquote><br />
''...if a contribution is viewed many times without being changed or deleted, it is likely to be <s>a</s> valuable.''</blockquote><br />
:'''Critique:'''<br />
Or, equally likely, the contribution is not being read critically, or even read at all. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add content that is wordy, boring, and dense. Prose that intimidates or sedates the reader would be so bland as to encourage skimming (rather than editing!), every time it is viewed.<br />
<br><br />
'''4. From the study:'''<br />
<blockquote><br />
''Our software does not track persistent words if text is "cut-and-pasted" from one article to another. If an editor moves a block of text from one article to another, PWVs after the move will be credited to the moving editor, not to the original editors.''</blockquote><br />
:'''Critique:'''<br />
Large credit goes, then, to "text movers" rather than "text creators". People who move a lot of text around will typically be busy-body administrators, rather than the careful scholars who painstakingly wrote the material in the first place. It is a known fact that the busiest administrators do a lot of "tidying" of major articles which lack any trace of their own content. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to become an administrator, then move a bunch of well-written content from article to article, which is frequently done among articles like "History of Tuscany" to "History of Italy" to "History of the Mediterranean" to "History of Europe" to the God-awful "History of western Eurasia".<br />
<br><br />
'''5. From the study:'''<br />
<blockquote><br />
''We exclude anonymous editors from some analyses, because IPs are not stable: multiple edits by the same human might be recorded under different IPs, and multiple humans can share an IP.''</blockquote><br />
:'''Critique:'''<br />
The same could be said for registered user accounts, which can be used from different IP addresses, by different people who know the password. It is a fact that some contributors to this very Chance News wiki are known to share registered Wikipedia user accounts. Regardless, the study itself found that anonymous IPs made 9 trillion edits out of a total of 34 trillion. Why would the study therefore exclude over 26% of the sample? This would have the effect of elevating the relative strength of contributions by a finite number of registered accounts, which is exactly what the study concludes. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to set up an account that he then shares with other like-minded individuals, so that more round-the-clock editing is possible, thereby building credibility in the community as a "dedicated Wikipedian". <br />
<br><br />
'''6. From the study:'''<br />
<blockquote><br />
''Reverts take two forms: '''identity revert''', where the post-revert revision is identical to a previous version, and '''effective revert''', where the effects of prior edits are removed (perhaps only partially), but the new text is not identical to any prior revision. ...In this paper, we consider only identity reverts.''</blockquote><br />
:'''Critique:'''<br />
Identity reverts, since they are a "button" tool that may seem intimidating to an average user, are probably more likely to be used by administrators, not scholars. Therefore, this study again gives extra strength to the actions of mop-wielding admins, rather than earnest shapers of Wikipedia. <br />
:'''Gaming the system:'''<br />
To count for more in this study, you wouldn't ever want to work to "improve" fixable recent content in Wikipedia. Rather, revert it, then re-write it in your own words.<br />
<br><br />
'''7. From the study:'''<br />
<blockquote><br />
''We believe it is reasonable to assume that essentially all damage is repaired within 15 revisions.''</blockquote><br />
:'''Critique:'''<br />
This may be so, but Figure 8 in the report also shows that 20% of the "Damaged-Loose" content incidents in Wikipedia are viewed by at least 30 people before they get fixed. Ten percent of such mistakes are viewed by well over 100 people before repaired. <br />
:'''Gaming the system:'''<br />
Learning to write mistaken or vandalistic prose in such a way that many, many people read it without "noticing" that it is wrong would be a way to further extend the time and views until detection. The libelous content written about [http://en.wikipedia.org/wiki/Seigenthaler_controversy John Seigenthaler, Sr.] and about [http://en.wikipedia.org/wiki/Fuzzy_Zoeller#Controversies Fuzzy Zoeller] went unnoticed for a number of weeks or months without causing any alarm. An effective way to make unsuspecting readers believe a lie in Wikipedia is to show a reference citation next to the false content. The reference need not even link to a source making the same claim you are making.<br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4713Chance News 312007-11-10T04:22:05Z<p>Thekohser: /* Potential bias in the study */ Continuation</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 or non-white, with Inter Fielding, 19, Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
(This submission to Chance News 31 will be expanded, but it is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our guess is that the Minnesota study would have accepted a passage like this as "undamaged", but we still need to read the white paper itself.)<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
===Potential bias in the study===<br />
'''From the study:'''<br />
<blockquote><br />
''We assume that one serving of an article by a Wikipedia server is a reasonable proxy for one view of that article by a user.''</blockquote><br />
:'''Critique:'''<br />
Humans don't read the entire article every time they load one in their browser. [http://www.poynterextra.org/eyetrack2004/main.htm Studies have shown] that readers of web pages tend to focus most of their priority on the top-left portion of the page. Therefore, this study is giving equal weight to words that appear at the bottom of an article, even though there is disproportionate reader emphasis on the first paragraph or two of any Wikipedia article.<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to bury his content in the middle or toward the end of Wikipedia articles, though fewer people being served the article would actually read his content.<br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''A tempting proxy for article views is article edits. However, we found essentially no correlation between views and edits in the request logs.''</blockquote><br />
:'''Critique:'''<br />
Why was there "essentially no correlation"? Popular, often-viewed pages on Wikipedia (examples may include George W. Bush, Barack Obama, evolution, and list of big-bust models and performers) are frequently semi-protected (only registered users with 4 days of tenure may modify the article) or fully-protected (only administrators my access the edit feature). Therefore, a powerful ''inverse'' relationship between views and edits would exist for those pages; quite possibly throwing off the otherwise intuitive correlation between article views and article edits. Were the study's authors cognizant of this?<br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add his content to contentious, popular articles, just before they are "locked down" from further editing. A Wikipedia administrator would have the capacity to make substantial edits to an article just before himself locking down (or asking an admin colleague to lock down) the very same article.<br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''...if a contribution is viewed many times without being changed or deleted, it is likely to be <s>a</s> valuable.''</blockquote><br />
:'''Critique:'''<br />
Or, equally likely, the contribution is not being read critically, or even read at all. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add content that is wordy, boring, and dense. Prose that intimidates or sedates the reader would be so bland as to encourage skimming (rather than editing!), every time it is viewed.<br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''Our software does not track persistent words if text is "cut-and-pasted" from one article to another. If an editor moves a block of text from one article to another, PWVs after the move will be credited to the moving editor, not to the original editors.''</blockquote><br />
:'''Critique:'''<br />
Large credit goes, then, to "text movers" rather than "text creators". People who move a lot of text around will typically be busy-body administrators, rather than the careful scholars who painstakingly wrote the material in the first place. It is a known fact that the busiest administrators do a lot of "tidying" of major articles which lack any trace of their own content. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to become an administrator, then move a bunch of well-written content from article to article, which is frequently done among articles like "History of Tuscany" to "History of Italy" to "History of the Mediterranean" to "History of Europe" to the God-awful "History of western Eurasia".<br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''We exclude anonymous editors from some analyses, because IPs are not stable: multiple edits by the same human might be recorded under different IPs, and multiple humans can share an IP.''</blockquote><br />
:'''Critique:'''<br />
The same could be said for registered user accounts, which can be used from different IP addresses, by different people who know the password. It is a fact that some contributors to this very Chance News wiki are known to share registered Wikipedia user accounts. Regardless, the study itself found that anonymous IPs made 9 trillion edits out of a total of 34 trillion. Why would the study therefore exclude over 26% of the sample? This would have the effect of elevating the relative strength of contributions by a finite number of registered accounts, which is exactly what the study concludes. <br />
:'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to set up an account that he then shares with other like-minded individuals, so that more round-the-clock editing is possible, thereby building credibility in the community as a "dedicated Wikipedian". <br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''Reverts take two forms: '''identity revert''', where the post-revert revision is identical to a previous version, and '''effective revert''', where the effects of prior edits are removed (perhaps only partially), but the new text is not identical to any prior revision. ...In this paper, we consider only identity reverts.''</blockquote><br />
:'''Critique:'''<br />
Identity reverts, since they are a "button" tool that may seem intimidating to an average user, are probably more likely to be used by administrators, not scholars. Therefore, this study again gives extra strength to the actions of mop-wielding admins, rather than earnest shapers of Wikipedia. <br />
:'''Gaming the system:'''<br />
To count for more in this study, you wouldn't ever want to work to "improve" fixable recent content in Wikipedia. Rather, revert it, then re-write it in your own words.<br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''We believe it is reasonable to assume that essentially all damage is repaired within 15 revisions.''</blockquote><br />
:'''Critique:'''<br />
This may be so, but Figure 8 in the report also shows that 20% of the "Damaged-Loose" content incidents in Wikipedia are viewed by at least 30 people before they get fixed. Ten percent of such mistakes are viewed by well over 100 people before repaired. <br />
:'''Gaming the system:'''<br />
Learning to write mistaken or vandalistic prose in such a way that many, many people read it without "noticing" that it is wrong would be a way to further extend the time and views until detection. The libelous content written about [http://en.wikipedia.org/wiki/Seigenthaler_controversy John Seigenthaler, Sr.] and about [http://en.wikipedia.org/wiki/Fuzzy_Zoeller#Controversies Fuzzy Zoeller] went unnoticed for a number of weeks or months without causing any alarm. An effective way to make unsuspecting readers believe a lie in Wikipedia is to show a reference citation next to the false content. The reference need not even link to a source making the same claim you are making.<br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4712Chance News 312007-11-09T21:59:42Z<p>Thekohser: /* The Unbreakable Wikipedia? */ Critiques of the study</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 or non-white, with Inter Fielding, 19, Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
(This submission to Chance News 31 will be expanded, but it is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our guess is that the Minnesota study would have accepted a passage like this as "undamaged", but we still need to read the white paper itself.)<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
===Potential bias in the study===<br />
'''From the study:'''<br />
<blockquote><br />
''We assume that one serving of an article by a Wikipedia server is a reasonable proxy for one view of that article by a user.''</blockquote><br />
'''Critique:'''<br />
Humans don't read the entire article every time they load one in their browser. [http://www.poynterextra.org/eyetrack2004/main.htm Studies have shown] that readers of web pages tend to focus most of their priority on the top-left portion of the page. Therefore, this study is giving equal weight to words that appear at the bottom of an article, even though there is disproportionate emphasis on the first paragraph or two of any Wikipedia article.<br />
'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to bury his content in the middle or toward the end of Wikipedia articles.<br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''A tempting proxy for article views is article edits. However, we found essentially no correlation between views and edits in the request logs.''</blockquote><br />
'''Critique:'''<br />
Why was there "essentially no correlation"? Popular, often-viewed pages on Wikipedia (examples may include George W. Bush, Barack Obama, evolution, and list of big-bust models and performers) are frequently semi-protected (only registered users with 4 days of tenure may modify the article) or fully-protected (only administrators my access the edit feature). Therefore, a powerful ''inverse'' relationship between views and edits would exist for those pages; quite possibly throwing off the otherwise intuitive correlation between article views and article edits. Were the study's authors cognizant of this?<br />
'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add his content to contentious, popular articles, just before they are "locked down" from further editing. A Wikipedia administrator would have the capacity to make substantial edits to an article just before himself locking down (or asking an admin colleague to lock down) the very same article.<br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''...if a contribution is viewed many times without being changed or deleted, it is likely to be <s>a</s> valuable.''</blockquote><br />
'''Critique:'''<br />
Or, equally likely, the contribution is not being read critically, or even read at all. <br />
'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to add content that is wordy, boring, and dense. Prose that intimidates or sedates the reader would be so bland as to encourage skimming (rather than editing!), every time it is viewed.<br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''Our software does not track persistent words if text is "cut-and-pasted" from one article to another. If an editor moves a block of text from one article to another, PWVs after the move will be credited to the moving editor, not to the original editors.''</blockquote><br />
'''Critique:'''<br />
Large credit goes, then, to "text movers" rather than "text creators". People who move a lot of text around will typically be busy-body administrators, rather than the careful scholars who painstakingly wrote the material in the first place. It is a known fact that the busiest administrators do a lot of "tidying" of major articles which lack any sign of their original content. <br />
'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to become an administrator, then move a bunch of well-written content from article to article, which is frequently done among articles like "History of Tuscany" to "History of Italy" to "History of the Mediterranean" to "History of Europe" to the God-awful "History of western Eurasia".<br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''We exclude anonymous editors from some analyses, because IPs are not stable: multiple edits by the same human might be recorded under different IPs, and multiple humans can share an IP.''</blockquote><br />
'''Critique:'''<br />
The same could be said for registered user accounts, which can be used from different IP addresses, by different people who know the password. It is a fact that some contributors to this very Chance News wiki are known to share registered Wikipedia user accounts. Regardless, the study itself found that anonymous IPs made 9 trillion edits out of a total of 34 trillion. Why would the study therefore exclude over 26% of the sample? This would have the effect of elevating the relative strength of contributions by a finite number of registered accounts, which is exactly what the study concludes. <br />
'''Gaming the system:'''<br />
An editor who wished to maximize his "Persistent word views" legacy would be wise to set up an account that he then shares with other like-minded individuals, so that more round-the-clock editing is possible, thereby building credibility in the community as a "dedicated Wikipedian". <br />
<br><br />
'''From the study:'''<br />
<blockquote><br />
''Reverts take two forms: identity revert, where the post-revert revision is identical to a previous version, and effective revert, where the effects of prior edits are removed...''</blockquote><br />
'''Critique:'''<br />
Will continue... <br />
'''Gaming the system:'''<br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4711Chance News 312007-11-09T21:22:45Z<p>Thekohser: Snell replied by e-mail...</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 or non-white, with Inter Fielding, 19, Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.economist.com/world/britain/displaystory.cfm?story_id=10063908 Undercounted and over here,] The Economist, 1st Nov 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
(This submission to Chance News 31 will be expanded, but it is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our guess is that the Minnesota study would have accepted a passage like this as "undamaged", but we still need to read the white paper itself.)<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=ChanceWiki:About&diff=13094ChanceWiki:About2007-11-09T17:46:25Z<p>Thekohser: it's --> its</p>
<hr />
<div>The Chance Wiki provides reviews of articles in the media that use probability or statistical concepts (chance news). Its purpose is to help the general public better understand chance news and also to allow teachers of probability or statistics to use current chance news in their courses.</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Main_Page&diff=4782Main Page2007-11-09T17:40:55Z<p>Thekohser: Quotes</p>
<hr />
<div><center>[[Image:news.gif |300px]] </center><br />
<br />
*[[Chance News 31]]: 11/5/07 to ?--Under Construction<br />
*[[Chance News 30]]: 9/7/07 to 11/4/07 -- ''Newest edition''<br />
*[[Oscar winners do not live longer]] <br />
*[[Previous Chance News]]<br />
<br />
*To obtain an account allowing you to login, email jlsnell@dartmouth.edu with subject "chance wiki account".This will allow you to edit existing items and add new items. <br />
*To be notified when a new chance news is posted register [http://listserv.dartmouth.edu/Archives/chance.html here].<br />
<br />
Chance News reviews current issues in the news that use probability or statistical concepts. Its aim is to give the general public a better understanding of chance news as reported by the media and to allow teachers of probability and statistics courses to liven up their courses with current news. Issues from 1992 to 2004,are archived on the [http://www.dartmouth.edu/~chance Chance Website] where you will also find other resources for teaching a probability or statistic course. <br />
<br />
Chance News will continue to be freely available under the [http://www.gnu.org/copyleft/fdl.html GNU Free Documentation License]</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Main_Page&diff=4707Main Page2007-11-09T17:40:42Z<p>Thekohser: Not "version", but edition</p>
<hr />
<div><center>[[Image:news.gif |300px]] </center><br />
<br />
*[[Chance News 31]]: 11/5/07 to ?--Under Construction<br />
*[[Chance News 30]]: 9/7/07 to 11/4/07 -- ''Newest edition"<br />
*[[Oscar winners do not live longer]] <br />
*[[Previous Chance News]]<br />
<br />
*To obtain an account allowing you to login, email jlsnell@dartmouth.edu with subject "chance wiki account".This will allow you to edit existing items and add new items. <br />
*To be notified when a new chance news is posted register [http://listserv.dartmouth.edu/Archives/chance.html here].<br />
<br />
Chance News reviews current issues in the news that use probability or statistical concepts. Its aim is to give the general public a better understanding of chance news as reported by the media and to allow teachers of probability and statistics courses to liven up their courses with current news. Issues from 1992 to 2004,are archived on the [http://www.dartmouth.edu/~chance Chance Website] where you will also find other resources for teaching a probability or statistic course. <br />
<br />
Chance News will continue to be freely available under the [http://www.gnu.org/copyleft/fdl.html GNU Free Documentation License]</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Main_Page&diff=4706Main Page2007-11-09T17:40:20Z<p>Thekohser: Cleanup</p>
<hr />
<div><center>[[Image:news.gif |300px]] </center><br />
<br />
*[[Chance News 31]]: 11/5/07 to ?--Under Construction<br />
*[[Chance News 30]]: 9/7/07 to 11/4/07 -- ''Newest version''<br />
*[[Oscar winners do not live longer]] <br />
*[[Previous Chance News]]<br />
<br />
*To obtain an account allowing you to login, email jlsnell@dartmouth.edu with subject "chance wiki account".This will allow you to edit existing items and add new items. <br />
*To be notified when a new chance news is posted register [http://listserv.dartmouth.edu/Archives/chance.html here].<br />
<br />
Chance News reviews current issues in the news that use probability or statistical concepts. Its aim is to give the general public a better understanding of chance news as reported by the media and to allow teachers of probability and statistics courses to liven up their courses with current news. Issues from 1992 to 2004,are archived on the [http://www.dartmouth.edu/~chance Chance Website] where you will also find other resources for teaching a probability or statistic course. <br />
<br />
Chance News will continue to be freely available under the [http://www.gnu.org/copyleft/fdl.html GNU Free Documentation License]</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4709Chance News 312007-11-08T06:41:11Z<p>Thekohser: Register a new account?</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
Note: This article is available from Lexis Nexis. Later in the article it is stated that there was a single winner and the ticket was bought at Patel's Price Cutter in Kaeo but not yet claimed. (It was claimed later by a couple who do not live in Kaeo). So why is this a Forsooth? Laurie Snell<br />
<br />
---- <br />
<br />
<blockquote>Of Italy's 151 Series A players, 52 or non-white, with Inter Fielding, 19, Juventus 12, AC Milan 13, AS Roma 12 and Udinese 10. Messina has eight.<br><div align=right> ''The Times''<br> 30 November 2005</div></blockquote><br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
(This submission to Chance News 31 will be expanded, but it is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our guess is that the Minnesota study would have accepted a passage like this as "undamaged", but we still need to read the white paper itself.)<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
==Next item==<br />
Begin here<br />
<br />
==New accounts==<br />
I know the newsletter itself is not the best place to seek assistance, but is there some reason that new account registration here seems to be unavailable? Is the software messed up, or is restricting registration by design? --[[User:Thekohser|Thekohser]] 01:41, 8 Nov 2007 (EST)</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Help:Contents&diff=13054Help:Contents2007-11-08T06:39:23Z<p>Thekohser: Spelling</p>
<hr />
<div>You can find help on most topics by going to [http://en.wikipedia.org/wiki/Wikipedia:Tutorial Wikipedia Tutorial.] <br />
Here are some things that are in the tutorial that we found particularly usefull.<br />
*[http://meta.wikimedia.org/wiki/Help Editing: Help]<br />
*[http://en.wikipedia.org/wiki/Wikipedia:External_links#External_links_section External Links] <br />
*[http://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style_%28links%29#Internal_links Internal Links]<br />
*[http://en.wikipedia.org/wiki/Wikipedia:Picture_tutorial How to Use images]<br />
*[http://en.wikipedia.org/wiki/Wikipedia:How_to_use_tables How to use tables]<br />
*[http://en.wikipedia.org/wiki/Wikipedia:TeX_markup Special characters, mathematics]</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4700Chance News 312007-11-07T04:36:33Z<p>Thekohser: /* The Unbreakable Wikipedia? */ Otto of Germany?</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
<br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
(This submission to Chance News 31 will be expanded, but it is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our guess is that the Minnesota study would have accepted a passage like this as "undamaged", but we still need to read the white paper itself.)<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the '''Carpathians they, in 896, occupied''' the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by '''Otto of Germany''' at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4699Chance News 312007-11-06T19:58:22Z<p>Thekohser: /* The Unbreakable Wikipedia? */ of <the> Western?</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
<br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
(This submission to Chance News 31 will be expanded, but it is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our guess is that the Minnesota study would have accepted a passage like this as "undamaged", but we still need to read the white paper itself.)<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the Carpathians they, in 896, occupied the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by Otto of Germany at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" '''of Western''' Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4697Chance News 312007-11-06T19:57:03Z<p>Thekohser: Blockquote</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
<br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
(This submission to Chance News 31 will be expanded, but it is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our guess is that the Minnesota study would have accepted a passage like this as "undamaged", but we still need to read the white paper itself.)<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
<blockquote><br />
''As the Viking raids subsided the Magyars arrived. Crossing the Carpathians they, in 896, occupied the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by Otto of Germany at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" of Western Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</blockquote><br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4696Chance News 312007-11-06T19:36:44Z<p>Thekohser: Next item placeholder</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
<br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
(This submission to Chance News 31 will be expanded, but it is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our guess is that the Minnesota study would have accepted a passage like this as "undamaged", but we still need to read the white paper itself.)<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
''As the Viking raids subsided the Magyars arrived. Crossing the Carpathians they, in 896, occupied the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by Otto of Germany at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" of Western Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''<br />
<br />
==Next item==<br />
Begin here</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_31&diff=4695Chance News 312007-11-06T19:35:57Z<p>Thekohser: Unbreakable Wikipedia?</p>
<hr />
<div>==Quotation==<br />
<br />
<blockquote> Statistics are no substitute for judgment.<br />
<div align=right> Henry Clay</div></blockquote><br />
==Forsooth==<br />
<br />
The following Forsooth from the Nov. 2007 issue of RSS NEWS.<br />
<br />
<blockquote>The odds of an $18 million Lotto win are one in 30 million but in the tiny Northland town of Kaeo they've been slashed to just one in 500. The town is abuzz with gossip that it could be home to New Zealand's biggest ever Lotto winner but Far North district councillor Sue Shepherd says the 500 residents are keeping their cards, and their tickets, close to their chest.<br />
<br />
<div align=right>The Dominion Post, New Zealand<br><br />
22 May 2006 </div></blockquote><br />
<br />
<br />
<br />
==Using Statistics to bust myths==<br />
<br />
[http://freakonomics.blogs.nytimes.com/2007/10/25/the-mythbusters-answer-your-questions/ The MythBusters Answer Your Questions] Stephen J. Dubner, Freakonomics Blog, October 25, 2007.<br />
<br />
"The MythBusters" is a television show on The Discovery Channel where Jamie Hyneman and Adam Savage examine commonly held myths and see if they have any validity. Their prior experience was in movie special effects and stunts, and sometimes their experiments lead to big (but carefully controlled) explosions. They were interviewed on the Freakonomics blog, and there were a pair of the questions asking why they didn't use more Statistics in their investigations.<br />
<br />
<blockquote>"Q: Often, when testing a myth, you conduct one full scale test and then draw your conclusions. I know you are both aware of the scientific method and the need to run multiple trials to fully prove or disprove a theory. How confident are you that when you’ve run one test on a myth, you can then accurately capture whether or not it is true?"</blockquote><br />
<br />
and<br />
<br />
<blockquote>"Q: How much statistics training do you guys have, and how much statistics do you use off camera? I get frustrated with the show over what appears to be a lack of statistical knowledge and rigor. (I’m thinking of the “football kick with helium” episode in particular, but the issue is sort of endemic to the show.) I realize that statistics makes for bad TV, while building machines that shoot things and break things make good TV. So the Freakonomics-y question would be: how much of this type of stuff is hidden off-camera?"</blockquote><br />
<br />
Both Jamie and Adam point out their time and budget limitations and remind us that the show has to be entertaining as well as illustrate a scientific approach to investigation. Adam does admit that he'd like to include more statistics, though.<br />
<br />
<blockquote>ADAM: These two (very difficult), questions are similar, so I’ll answer them together. I would love to get more statistics into the show, and I’ve been talking to a statistician friend about just that. It’s true that statistics are not very telegenic, and are often difficult to get across.<br />
<br />
We do worry about consistency, and it’s usually because our data sets are so small. With larger sets, we can work with things like standard deviation; but with a data set of 2, we don’t have that luxury.<br />
<br />
Also, I sense a frustration in some of these questions. I’ll say this: I don’t pretend to be a scientist. We’re not deliverers of scientific truth. But I am curious. And if there’s one complaint I have about people, it’s that most of them aren’t curious enough to look around and figure stuff out for themselves. So if you’re yelling at me at the TV, you’re involved, and as such, I’ve done my job. </blockquote><br />
<br />
===Questions===<br />
<br />
1. Is it true that statistics are not very telegenic? Are there any aspects of Statistics that would lend themselves to a medium like television?<br />
<br />
2. The Discovery Channel website has an [http://dsc.discovery.com/fansites/mythbusters/episode/episode.html episode guide]. Select a show and explain how statistics could be used to investigate the myth(s) on that episode.<br />
<br />
Submitted by Steve Simon<br />
<br />
==Migration statistics==<br />
<br />
[http://uk.reuters.com/article/domesticNews/idUKL3028018520071030 Stats office to improve data on migration flows,] Reuters, 30th Oct 2007.<br><br />
[http://politics.guardian.co.uk/homeaffairs/story/0,,2201872,00.html Smith apologises for foreign workers error,] Guardian Unlimited, 30th October 2007.<br><br />
[http://www.guardian.co.uk/britain/article/0,,2204561,00.html How many people live in Britain? We haven't the foggiest idea,] The Guardian, 3rd November 2007.<br><br />
<br />
UK politicians were recenly forced to answer the question <em>how many foreign workers were in the country?</em> but were unable to do so.<br />
The initial estimate (800,000) had to be revised upwards, not once, but twice (1.1 million, then the government's chief statistician said it was more like 1.5m), much to the government's embarrassment.<br />
<br />
The shadow pensions secretary, Chris Grayling, said<br />
<blockquote><br />
This situation just gets worse. It's clear we simply can't trust the figures or statements put out by the Government on migrant workers in the UK.<br />
Ministers need to carry out an urgent review of how they handle this data and need to clear up once and for all how many people come to work in Britain.<br />
</blockquote><br />
<br />
Then just a few hours after the government was forced to admit it had hugely <br />
underestimated the number of immigrant workers, <br />
the (UK's) national statistics office (ONS) announced changes to the way it collects migration data.<br />
Publishing an interim report into the issue, the ONS said it would increase the sample sizes for its International Passenger Survey and consider making better use of administrative data, such as school and patient registers.<br />
[http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm The (UK's) International Passenger Survey] currently samples around 0.3 percent of people entering and leaving the country at 16 airports, 21 ferry routes and the Channel Tunnel.<br />
The ONS said extra "filter shifts" would be introduced at specific airports from next April to reflect the higher number of migrants who arrived and departed from these airports in 2006.<br />
<br />
How does the survey work? According to Michael Blastland writing in the Evening Standard<br />
<blockquote><br />
For ferry passengers, a team in blue blazers stands at the top of each of stairs into the passenger deck and scribbles a quick description of every 10th [passenger] aboard. As the ship sails, the blazers go hunting for their sample, the woman in the green hat, the trucker in overalls by the slot machine, and ask them if they plan to stay, then extrapolate.<br />
</blockquote><br />
One objective of this survey is to say how many of the 2.17m jobs created since 1997 have been filled by foreign nationals, the statistic that caused the furore.<br />
<br />
[http://www.statistics.gov.uk/about/other_letters/richard_alldritt_23aug04.asp Richard Alldritt,] the Statistics Commission's chief executive, wants the government to spend more money on improved monitoring of travel movements: the international passenger survey has become a key estimate of migration levels, but Alldritt said it didn't cover every port and that there was <br />
<blockquote><br />
no guarantee that those surveyed give accurate answers and the results have to be scaled up enormously.<br />
</blockquote><br />
The lack of reliable data on migrant flows has been a major headache for policymakers, complicating everything from the allocation of government resources to the setting of interest rates.<br />
<br />
US-born, National Statistician [http://en.wikipedia.org/wiki/Karen_Dunnell Karen Dunnell] said<br />
<blockquote><br />
The ONS is engaged in a major programme to improve further the quality of its migration statistics.<br />
The International Passenger Survey is a vital source of data on this, so improving the sampling of migrants is a step forward in this very important area of our work.<br />
</blockquote><br />
<br />
This week on [http://news.bbc.co.uk/1/hi/programmes/question_time/default.stm BBC's Question Time,] David Dimbleby asked the audience if they would believe any statistic mentioned by a politician and the audience roared 'No!'.<br />
<br />
===Questions===<br />
* Speculate on [http://qb.soc.surrey.ac.uk/surveys/ips/ipsintro.htm what questions might be asked] in such a survey?<br />
* What criteria might the ONS use to decide which airports to locate their extra 'filter shifts' at?<br />
* The revised figure of 1.5m included children. What is the implication of counting them as 'workers'?<br />
* Sir Andrew Green, chairman of [http://www.migrationwatchuk.com/ Migration Watch,] which campaigns against mass immigration, claimed that the rise was equivalent to a city the size of Coventry. Is it fair and unbiased to compare the size of the error in the initial estimate to a specific city? Can you think of alternative analogies?<br />
<br />
===Further reading===<br />
* The [http://www.statistics.gov.uk/ssd/surveys/international_passenger_survey.asp International Passenger Survey] is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. <br />
** Over a quarter of million face-to-face interviews are carried out each year with passengers entering and leaving the UK through the main airports, seaports and the Channel Tunnel.<br />
** There are six versions of the questionnaire depending on the mode of transport (air, sea or Eurostar) and which direction the passenger is travelling in (arrivals or departures).<br />
** The sampling procedures for air, sea and tunnel passengers are slightly different but the underlying principle for each is similar. In the absence of a readily available sampling frame, <em>time shifts</em> or crossings are sampled at the first stage. During these shifts or crossings, the travellers are counted as they pass a particular point (for example, after passing through passport control) then travellers are systematically chosen at fixed intervals from a random start. <br />
** Interviewing is carried out throughout the year and over a quarter of a million face-to-face interviews are conducted each year, and represents about 1 in every 500 passengers.<br />
** The interview usually take 3-5 minutes and contains questions about passengers’ country of residence (for overseas residents) or country of visit (for UK residents), the reason for their visit, and details of their expenditure and fares. <br />
*** There are additional questions for passengers migrating to or from the UK. <br />
*** While much of the content of the interview remains the same from one year to the next, new questions are sometimes added or appear periodically on the survey.<br />
<br />
Submitted by John Gavin.<br />
<br />
==The Unbreakable Wikipedia?==<br />
<br />
[http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf Creating, Destroying, and Restoring Value in Wikipedia] Department of Computer Science and Engineering at the University of Minnesota, 2007.<br><br />
[http://www.myfoxtwincities.com/myfox/pages/News/Detail?contentId=4840071&version=1&locale=EN-US&layoutCode=TSTY&pageId=3.2.1 Univ. of Minnesota: Less Than 1/2 Percent of Wikipedia Content is Damaged] Fox News (Twin Cities), November 5, 2007.<br><br />
<br />
The University of Minnesota computer science and engineering faculty and students found that only a few edits inflict damage on the integrity of content within Wikipedia and that damage is typically fixed quickly. The study estimated a probability of less than one-half percent (0.0037) that the typical viewing of a Wikipedia article would find it in a damaged state.<br />
<br />
(This submission to Chance News 31 will be expanded, but it is important to ask incisive questions about this study, especially to demand a definition of what constitutes "vandalism" and "damage". The following passage from Wikipedia is downright horrid, but would it constitute a "damaged" piece of content? Our guess is that the Minnesota study would have accepted a passage like this as "undamaged", but we still need to read the white paper itself.)<br />
<br />
From the "[http://en.wikipedia.org/wiki/History_of_western_Eurasia History of western Eurasia]" article in Wikipedia:<br />
<br />
''As the Viking raids subsided the Magyars arrived. Crossing the Carpathians they, in 896, occupied the Upper Tisza river, from which they conducted raids through much of Western Europe. However, in 955 they were defeated by Otto of Germany at the Battle of Lechfeld. The defeat was so crushing that '''the Magyars decided that 'if you can't beat them join them'''' and in 1000 their King was accepting his royal regalia from the Pope. Otto on the strength of that victory was able to secure the '''tittle''' of Emperor. This German based Holy Roman Empire was to be the major power in Christian Europe '''for some time to come'''. As well as this "rebirth" of Western Roman Empire, the Eastern Roman Empire '''continued to be the up'''.''</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_30&diff=4626Chance News 302007-10-23T12:53:14Z<p>Thekohser: /* Forsooth */ solved --> fixed</p>
<hr />
<div>==Quotations==<br />
==Forsooth==<br />
The following Forsooth was suggested by John Vokey.<br />
<br />
<blockquote>[http://www.theglobeandmail.com/servlet/story/RTGAM.20070911.wvitamin11/BNStory/specialScienceandHealth/home Vitamin D can lower risk of death by 7 percent]<div align=right> Martin Mitttelstaedt<br> Globe and Mail<br> September 11, 2007<br> </div></blockquote><br />
<br />
This is an interesting example. In the article we read "people who were given a vitamin D supplement had a 7-per-cent lower risk of premature death than those who were not." and "It appears to be a life extender". So perhaps many of our forsooths come from the fact that copy editors write the headlines. (Lauie Snell)<br />
<br />
<br />
----<br />
The following Forsooth was suggested by Gregory Kohs.<br />
<br />
<blockquote>[http://philly.metro.us/metro/sports/article/Birds_fall_in_heartbreaker/10429.html Birds fall in heartbreaker]<div align=right> Andy Jasner<br> Metro<br> October 22, 2007<br> </div></blockquote><br />
<br />
''The <nowiki>[Philadelphia]</nowiki> Eagles’ problems in the red zone finally appeared to have been fixed when Donovan McNabb connected with tight end Matt Schobel for a 13-yard score with 4:57 left. It was the Eagles’ first touchdown in four trips inside the 20 during yesterday’s game. Entering the contest, the Eagles had scored just five touchdowns in 16 possessions in the red zone.''<br />
<br />
Note that prior to the game against the Bears, the Eagles had a 31.25% touchdown rate inside the 20-yard line. Note that this "problem" appeared to be solved by a game with a 25% red zone touchdown rate.<br />
<br />
==Supplement may help treat gambling addiction==<br />
[http://www.startribune.com/1244/story/1416861.html Miniapolis Star Tribune], September 12, 2007<br><br />
Maura Lerner<br />
<br />
There seems to be a never-ending supply of questionable statistical studies. Consider the recent Minneapolis Star Tribune account of September 12, 2007. A University of Minnesota researcher publishing in the September 15, 2007 issue of Biological Psychiatry treated "27 pathological gamblers for eight weeks" with an amino acid supplement, N-acetyl cysteine. "By the end, 60 percent said they had fewer urges to gamble." Of the 16 who reported a benefit, "13 remained in a follow-up study...five out the six on the supplement reported continued improvement, compared to two out of seven on a placebo." According to the researcher, "There does seem to be some effect, but you would need bigger numbers."<br />
<br />
Here are the results of the follow-up study as seen by Minitab:<br />
<br />
MTB > PTwo 6 5 7 2.<br />
<br />
Test and CI for Two Proportions <br />
<br />
<table width="49%" border="1"><br />
<tr> <br />
<td width="33%"><div align="center">Sample</div></td><br />
<td width="13%"><div align="center">X</div></td><br />
<td width="12%"><div align="center">N</div></td><br />
<td width="42%"><div align="center">Sample p</div></td><br />
</tr><br />
<tr> <br />
<td><div align="center">1</div></td><br />
<td><div align="center">5</div></td><br />
<td><div align="center">6</div></td><br />
<td><div align="center">0.833333</div></td><br />
</tr><br />
<tr> <br />
<td><div align="center">2</div></td><br />
<td><div align="center">2</div></td><br />
<td><div align="center">7</div></td><br />
<td><div align="center">0.285714</div></td><br />
</tr><br />
</table><br />
Difference = p (1) - p (2) <br><br />
<br />
Estimate for difference: 0.547619<br><br />
<br />
95% CI for difference: (0.0993797, 0.995858)<br><br />
<br />
Test for difference = 0 (vs not = 0): Z = 2.39 P-Value = 0.017<br><br />
<br />
Fisher's exact test: P-Value = 0.103<br><br />
<br />
NOTE: The normal approximation may be inaccurate for small samples.<br />
<br />
===Discussion===<br />
1.. Assume you are a frequentist, what about statistical significance? Note the discrepancy between the exact P-Value and the P-Value using the normal approximation.<br />
<br />
2.. Assume you are a Bayesian and thus immune to P-Value whether exact or due to a normal approximation, pick your priors and find the probability that there is a difference between the effect of the supplement and the effect of the placebo. <br />
<br />
3.. Aside from the choice of inference procedure, frequentist or Bayesian, what other flaws do you see in this study with regard to sample size and measurement of success?<br />
<br />
4.. Speculate as to why this study was reported in a Twin Cities newspaper and probably not elsewhere. <br />
<br />
5.. Speculate on what might happen if the 11 who did not respond to the supplement originally were put on the follow-up study.<br />
<br />
Submitted by Paul Alper<br />
<br />
==Excel 2007 arithmetic error==<br />
<br />
[http://blogs.msdn.com/excel/archive/2007/09/25/calculation-issue-update.aspx Calculation Issue Update] David Gainer, September 25, 2007.<br />
<br />
The Excel blog at Microsoft usually talks about product enhancements and future plans for development, but on September 25 had to admit an embarrassing problem with basic arithmetic in Excel 2007. A series of calculations such as 77.1*850, 20.4*3,212.5, 10.2*6,425, and 5.1*12,850 that should normally produce a value of 65,535 instead produce a result of 100,000. The result is actually stored in an acceptable binary form, but flaw occurs in the process of transforming the binary representation to a decimal form for display.<br />
<br />
Although there are an infinite number of rational numbers, a computer can only represent a finite number of these values in its storage. For the rest, the computer has to choose a value in binary that is reasonably close. Some numbers that have very simple representations in decimal, such as 0.1 do not have an exact representation in binary. Certain fractions, such as 1/3 and 1/7 have infinite expansions in decimal notation and have to be truncated. A larger list of fractions such as 1/10 have infinite expansion in binary representation, so that creates a slight inaccuracy. This slight inaccuracy produces a product for terms like 77.1*850 that are not quite 65,535 but slightly larger or smaller.<br />
<br />
According to the Microsoft blog, there are six binary numbers that lie between the decimal values of 65534.99999999995 and 65,535 that are not displayed properly in Excel 2007. Another six binary numbers that lie between 65,535.99999999995 and 65,536 also have problems. You can't enter these numbers directly in Excel, because Excel will round any directly entered values to 15 significant digits.<br />
<br />
It's probably not a coincidence that these numbers are close to 2^16. These values would have long strings of consecutive 1's in the binary representation. An entry on the Wolfram Blog, [http://blog.wolfram.com/2007/09/arithmetic_is_hardto_get_right.html?lid=perma Arithmetic is Hard--To Get Right, Mark Sofroniou], speculates that there is a problem with propagation of carries.<br />
<br />
This bug only affects values close to 65,535 and 65,536 when they are displayed as a final result. Intermediate calculations that produce one of these unfortunate 12 numbers are unaffected because it is the process of converting the binary representation to a decimal form for display that is flawed.<br />
<br />
The bug also does not appear to affect earlier versions of Excel. This error is reminiscent of the [http://en.wikipedia.org/wiki/Pentium_FDIV_bug Pentium FDIV bug].<br />
<br />
===Questions===<br />
<br />
1. According to the Microsoft blog, there are 9.2*10^18 possible binary values, and only 12 of them are affected by this bug. Would it be safe to say that the probability that any individual would encounter this bug is 12 / 9.2*10^18 = 1.3*10^-18?<br />
<br />
2. It is impossible to test every possible arithmetic calculation in a computer system. How would you design a testing system that evaluated a representative sample of possible arithmetic calculations?<br />
<br />
Submitted by Steve Simon<br />
<br />
==Uncertainties of Life==<br />
<br />
Statistics would be unnecessary if we lived in a strictly deterministic universe. Indeed, statistics and variability go together. Except, in journalism, where despite the decades of statistical education, the notion of variability is virtually nonexistent. A recent example may be found in an [http://hosted.ap.org/dynamic/stories/N/NEW_CANCER_DRUG?SITE=WIFON&SECTION=HOME&TEMPLATE=DEFAULT AP release] of September 26, 2007 entitled, "New Drug May Make Tumors Self-Destruct." The article refers to a presentation "at a meeting of the European Cancer Organization in Barcelona" and concerns a drug, "STA-4783, which has no effect on normal cells" while "causing tumor cells to self-destruct by overloading them with oxygen."<br />
<br />
The article states that "the drug doubled the amount of time that advanced melanoma patients survived without their cancer worsening:" average of 1.8 months vs. an average of 3.7 months. Further, the mortality statistics were an average of 7.8 months vs. an average of 12 months. We know that "28 received the standard chemotherapy" and 53 received the standard chemotherapy plus STA-4783. However, not a whisper about variation in either arm of the study.<br />
<br />
===Discussion===<br />
<br />
1.. Consider the "28" and "53" in the respective arms of the study. What does that imbalance suggest regarding dropout rates and/or randomization? <br />
<br />
2.. Assuming you are a frequentist, speculate on why there is no mention of P-Value, statistical significance or effect size. <br />
<br />
3.. The word "average" appears many times in the article. Explain why the mean or the median would be more appropriate. <br />
<br />
4.. Explain why a box plot would be very enlightening. <br />
<br />
5.. The article says "the drug doubled the amount of time that advanced melanoma patients survived without their cancer worsening." Looking at the data, how impressive is this in your eyes? That is, how do you view the "practical" significance of two extra months on average? <br />
<br />
6.. Although STA-4783 supposedly has no side effects, no mention is made of the potential cost of the drug. If it is deemed successful, speculate on what patients may have to pay for the drug.<br />
<br />
<br />
Submitted by Paul Alper<br />
<br />
==Depressed people follow a different power law distribution==<br />
[http://economist.com/science/displaystory.cfm?story_id=9861412 Something in the way he moves,] The Economist, Sep 27th 2007.<br><br />
<br />
This Economist article claims that depressed people move in a mathematically different way from other people.<br />
The paper underlying the article makes two assertions:<br />
* The durations of periods of physical activity (while resting) follow a [http://en.wikipedia.org/wiki/Power_law power law] distribution.<br />
* The resulting [http://en.wikipedia.org/wiki/Probability_distribution distributions] differ between healthy and clinically depressed people, to such an extent that this test could be used to diagnose [http://en.wikipedia.org/wiki/Clinical_depression clinical depression.]<br />
<br />
Power law distributions have been previously discussed in Chance News [http://chance.dartmouth.edu/chancewiki/index.php/Special:Search?search=%22power+law%22&go=Go on numerous occasions.]<br />
<br />
The data used to derive these conclusions <br />
consists of fourteen patients with major depressive disorder <br />
and eleven age-matched healthy control subjects.<br />
Accelerometers detected small changes in the acceleration of patients' wrists.<br />
Even slight movements of the subjects, <br />
ranging from, writing or working on a computer to physical exercise, <br />
are registered every minute for several days.<br />
The resulting data is a count per minute of the number of times the accelerometer<br />
registered a movement.<br />
<br />
[[Image:Figure1 from Universal Scaling Law in Human Behavioral Organization.JPG|frame|right|Source: part of figure 1 taken from [http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000099000013138103000001&idtype=cvips&gifs=Yes <em>Universal Scaling Law in Human Behavioral Organization,</em>] Yoshiharu Yamamoto, <em>et al,</em> Univ of Tokyo, Phys. Rev. Lett. 99, (2007).]]<br />
<br />
The attached figure, taken from the original paper, <br />
plots the raw count data over time for five days.<br />
The authors claim that these figures<br />
<blockquote><br />
show a clear circadian rest-activity cycle in the<br />
control subject, while in the patient, such a rhythmic<br />
pattern is much disrupted, reflecting the reported chronobiological<br />
abnormality in depression<br />
</blockquote><br />
In other words, the results highlight that there is a difference <br />
in the way that the healthy and the depressed spread their resting periods over the day:<br />
depressed patient shows bursts in the activity counts;<br />
control subjects are characterized by more sustained activity levels. <br />
This basic result confirmed a known feature of depressed people:<br />
<blockquote><br />
The normal daily rhythm that would lead to a high, <br />
steady number of counts during daylight hours and low counts during the night <br />
was replaced by occasional bursts of activity.<br />
</blockquote><br />
<br />
To aggregate the data over time,<br />
the authors estimated the cumulative distribution of durations <br />
of both resting periods.<br />
A resting (active) period's duration is defined as the total time <br />
that the count per minute remains below (above) some chosen threshold. <br />
<br />
The Economist claims that the surprising result in the paper is that<br />
plotting the lengths of low-activity periods against their frequency <br />
produces strikingly different patterns in healthy verses depressed people.<br />
It goes on to speculate that this discovery may provide another way of diagnosing major depression.<br />
<br />
The power-law results were only applicable for periods <br />
when patients and controls were resting. <br />
But the authors claim that results are consistent for varying choices of the threshold.<br />
In contrast, during active periods<br />
the cumulative distribution takes a 'stretched exponential form'.<br />
<br />
The authors claim:<br />
<blockquote><br />
Surprisingly, these statistical laws, <br />
after being rescaled by the mean waiting times, <br />
are not affected by altering the threshold value to calculate the waiting times. <br />
They share the distribution form for individuals considerably different<br />
in their daily living, and regardless of whether healthy or<br />
suffering from major depression, therefore <br />
suggesting the presence of universal laws governing human behavioral organization.<br />
</blockquote><br />
<br />
The Economist summarises a corollary conjectured by the authors:<br />
<blockquote><br />
(this result) also raises an interesting question about the nature of depression itself. <br />
That is because, when he looked for similar power-law curves in other areas, <br />
the one which he thought most resembled that exhibited by the depressed <br />
turned out to be the pattern of electrical activity shown by nerve cells isolated in a Petri dish <br />
and unable to contact their neighbours.<br />
<br />
It is both unnerving and intriguing that a mental disorder which isolates people from human society, <br />
and which must surely have its origins in some malfunction of the nerve cells, <br />
is reflected in the behaviour of cells that have themselves been isolated. <br />
Maybe this is just a coincidence but maybe it is not.<br />
</blockquote><br />
<br />
===Questions===<br />
* All the patients wore the accelerometer (aka activity monitor aka [http://www.theactigraph.com/?gclid=CMnUqIu8644CFRI-EAodejBUJg motion logger]) on the wrist of their non-dominant hand. Would you expect results to differ materially if the other hand, or a leg, was used? <br />
* The fourteen depressed patients wore their accelerometers for at least 18 days each, rising to 42 days in some cases. All eleven healthy controls wore their accelerometers for seven days. Does it matter that the time periods are much longer for the patients relative to the controls? <br />
** If so, how might a statistical analysis adjust for this? <br />
** Would it matter if the data from each patient was not taken from one continuous time period?<br />
** Are their enough patients in this experiment? Patients and controls were age-matched, why do you think that this was necessary? On the other hand, the sex of patients and controls is not mentioned, do you care?<br />
* The severity of depression of the patients was mild to moderate. Should the results have accounted for the degree of severity of the clinically depressed patients? <br />
** Can you map out in your mind how you might build a statistical model to do this? The objective might be a diagnostic tool for clinical depression, in which case, your model would have to be capable of distinguishing between mild (non-clinical) and chronic depression. Is the preliminary result outlined in this article sufficient to justify the time/expense of this extra work, in your view?<br />
** Do you think that the severity of a person's movements, rather than just the count of such movements per minute, is more informative? Speculate why you think this type of measurement was not recorded?<br />
* The data consists of the number of accelerometer counts per minute. Minute periods for which the count was zero were excluded from the analysis. Can you guess why the authors did this? Might it affect the results in some way?<br />
** The maximum number of counts that the accelerometer can count in one minute is 300. Is this relevant in any context?<br />
* Do you know what a '[http://en.wikipedia.org/wiki/Stretched_exponential_function stretched exponential] distribution or a [http://en.wikipedia.org/wiki/Cumulative_distribution_function#Complementary_cumulative_distribution_function complementary cumulative distribution function] is? Can you relate the former to a more commonly known distribution in statistics and do you know a more common term to describe the latter distribution? <br />
* The authors say <em>the [http://en.wikipedia.org/wiki/Kolmogorov-Smirnov_test Kolmogorov-Smirnov test] is used throughout.</em> What other tests might you like to see to distinguish patients from controls? <br />
** Do any of your tests account for the time order in which the data is recorded? If not, why not?<br />
** The authors report a p-value of 0.0001 for the different scaling exponents in the two fitted power law distributions. Does the low p-value surprise you? How does it relate to the number of people in the sample? The authors mention that this p-value is associated with a significantly longer (p < 0.001) mean resting-period duration in the patients (15 minutes) than in the control subjects (7 minutes). How might the number of patients and controls affect this statistic's p-value?<br />
** If the graph in the figure above are typical of all patients, as claimed, why would anyone bother to calculate a statistical test? Isn't it obvious that there is there is overwhelming empirical evidence from just exploring the data that the patterns in the two time series are completely different? Is there likely to be a statistical test that might show no difference between the two datasets? <br />
* Are you comfortable with the conjecture that it might be more than coincidence that electrical activity in nerve cells also follows a power law distribution?<br />
<br />
===Further reading===<br />
* [http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000099000013138103000001&idtype=cvips&gifs=Yes <em>Universal Scaling Law in Human Behavioral Organization,</em>] Yoshiharu Yamamoto, <em>et al,</em> Univ of Tokyo, Phys. Rev. Lett. 99, (2007). <br />
** This short four-page paper is currently available for free from [http://www.p.u-tokyo.ac.jp/~yamamoto/papers/prl08.pdf the author's website.]<br />
* Trivia - While browsing links related to this article - I stumbled across a [http://physicsworld.com/cws/article/news/23428/1/051015 neat graphical summary] of the numbers of letters sent and received by Darwin and Einstein over their lifetimes. The response times of both authors follow similar power law distributions (Source: [http://physicsworld.com/cws/article/news/23428/1/051015 Nature, 437, 1251).]<br />
<br />
Submitted by John Gavin.</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_30&diff=4625Chance News 302007-10-23T12:52:34Z<p>Thekohser: /* Forsooth */ Insert line</p>
<hr />
<div>==Quotations==<br />
==Forsooth==<br />
The following Forsooth was suggested by John Vokey.<br />
<br />
<blockquote>[http://www.theglobeandmail.com/servlet/story/RTGAM.20070911.wvitamin11/BNStory/specialScienceandHealth/home Vitamin D can lower risk of death by 7 percent]<div align=right> Martin Mitttelstaedt<br> Globe and Mail<br> September 11, 2007<br> </div></blockquote><br />
<br />
This is an interesting example. In the article we read "people who were given a vitamin D supplement had a 7-per-cent lower risk of premature death than those who were not." and "It appears to be a life extender". So perhaps many of our forsooths come from the fact that copy editors write the headlines. (Lauie Snell)<br />
<br />
<br />
----<br />
The following Forsooth was suggested by Gregory Kohs.<br />
<br />
<blockquote>[http://philly.metro.us/metro/sports/article/Birds_fall_in_heartbreaker/10429.html Birds fall in heartbreaker]<div align=right> Andy Jasner<br> Metro<br> October 22, 2007<br> </div></blockquote><br />
<br />
''The <nowiki>[Philadelphia]</nowiki> Eagles’ problems in the red zone finally appeared to have been fixed when Donovan McNabb connected with tight end Matt Schobel for a 13-yard score with 4:57 left. It was the Eagles’ first touchdown in four trips inside the 20 during yesterday’s game. Entering the contest, the Eagles had scored just five touchdowns in 16 possessions in the red zone.''<br />
<br />
Note that prior to the game against the Bears, the Eagles had a 31.25% touchdown rate inside the 20-yard line. Note that this "problem" appeared to be fixed by a game with a 25% red zone touchdown rate.<br />
<br />
==Supplement may help treat gambling addiction==<br />
[http://www.startribune.com/1244/story/1416861.html Miniapolis Star Tribune], September 12, 2007<br><br />
Maura Lerner<br />
<br />
There seems to be a never-ending supply of questionable statistical studies. Consider the recent Minneapolis Star Tribune account of September 12, 2007. A University of Minnesota researcher publishing in the September 15, 2007 issue of Biological Psychiatry treated "27 pathological gamblers for eight weeks" with an amino acid supplement, N-acetyl cysteine. "By the end, 60 percent said they had fewer urges to gamble." Of the 16 who reported a benefit, "13 remained in a follow-up study...five out the six on the supplement reported continued improvement, compared to two out of seven on a placebo." According to the researcher, "There does seem to be some effect, but you would need bigger numbers."<br />
<br />
Here are the results of the follow-up study as seen by Minitab:<br />
<br />
MTB > PTwo 6 5 7 2.<br />
<br />
Test and CI for Two Proportions <br />
<br />
<table width="49%" border="1"><br />
<tr> <br />
<td width="33%"><div align="center">Sample</div></td><br />
<td width="13%"><div align="center">X</div></td><br />
<td width="12%"><div align="center">N</div></td><br />
<td width="42%"><div align="center">Sample p</div></td><br />
</tr><br />
<tr> <br />
<td><div align="center">1</div></td><br />
<td><div align="center">5</div></td><br />
<td><div align="center">6</div></td><br />
<td><div align="center">0.833333</div></td><br />
</tr><br />
<tr> <br />
<td><div align="center">2</div></td><br />
<td><div align="center">2</div></td><br />
<td><div align="center">7</div></td><br />
<td><div align="center">0.285714</div></td><br />
</tr><br />
</table><br />
Difference = p (1) - p (2) <br><br />
<br />
Estimate for difference: 0.547619<br><br />
<br />
95% CI for difference: (0.0993797, 0.995858)<br><br />
<br />
Test for difference = 0 (vs not = 0): Z = 2.39 P-Value = 0.017<br><br />
<br />
Fisher's exact test: P-Value = 0.103<br><br />
<br />
NOTE: The normal approximation may be inaccurate for small samples.<br />
<br />
===Discussion===<br />
1.. Assume you are a frequentist, what about statistical significance? Note the discrepancy between the exact P-Value and the P-Value using the normal approximation.<br />
<br />
2.. Assume you are a Bayesian and thus immune to P-Value whether exact or due to a normal approximation, pick your priors and find the probability that there is a difference between the effect of the supplement and the effect of the placebo. <br />
<br />
3.. Aside from the choice of inference procedure, frequentist or Bayesian, what other flaws do you see in this study with regard to sample size and measurement of success?<br />
<br />
4.. Speculate as to why this study was reported in a Twin Cities newspaper and probably not elsewhere. <br />
<br />
5.. Speculate on what might happen if the 11 who did not respond to the supplement originally were put on the follow-up study.<br />
<br />
Submitted by Paul Alper<br />
<br />
==Excel 2007 arithmetic error==<br />
<br />
[http://blogs.msdn.com/excel/archive/2007/09/25/calculation-issue-update.aspx Calculation Issue Update] David Gainer, September 25, 2007.<br />
<br />
The Excel blog at Microsoft usually talks about product enhancements and future plans for development, but on September 25 had to admit an embarrassing problem with basic arithmetic in Excel 2007. A series of calculations such as 77.1*850, 20.4*3,212.5, 10.2*6,425, and 5.1*12,850 that should normally produce a value of 65,535 instead produce a result of 100,000. The result is actually stored in an acceptable binary form, but flaw occurs in the process of transforming the binary representation to a decimal form for display.<br />
<br />
Although there are an infinite number of rational numbers, a computer can only represent a finite number of these values in its storage. For the rest, the computer has to choose a value in binary that is reasonably close. Some numbers that have very simple representations in decimal, such as 0.1 do not have an exact representation in binary. Certain fractions, such as 1/3 and 1/7 have infinite expansions in decimal notation and have to be truncated. A larger list of fractions such as 1/10 have infinite expansion in binary representation, so that creates a slight inaccuracy. This slight inaccuracy produces a product for terms like 77.1*850 that are not quite 65,535 but slightly larger or smaller.<br />
<br />
According to the Microsoft blog, there are six binary numbers that lie between the decimal values of 65534.99999999995 and 65,535 that are not displayed properly in Excel 2007. Another six binary numbers that lie between 65,535.99999999995 and 65,536 also have problems. You can't enter these numbers directly in Excel, because Excel will round any directly entered values to 15 significant digits.<br />
<br />
It's probably not a coincidence that these numbers are close to 2^16. These values would have long strings of consecutive 1's in the binary representation. An entry on the Wolfram Blog, [http://blog.wolfram.com/2007/09/arithmetic_is_hardto_get_right.html?lid=perma Arithmetic is Hard--To Get Right, Mark Sofroniou], speculates that there is a problem with propagation of carries.<br />
<br />
This bug only affects values close to 65,535 and 65,536 when they are displayed as a final result. Intermediate calculations that produce one of these unfortunate 12 numbers are unaffected because it is the process of converting the binary representation to a decimal form for display that is flawed.<br />
<br />
The bug also does not appear to affect earlier versions of Excel. This error is reminiscent of the [http://en.wikipedia.org/wiki/Pentium_FDIV_bug Pentium FDIV bug].<br />
<br />
===Questions===<br />
<br />
1. According to the Microsoft blog, there are 9.2*10^18 possible binary values, and only 12 of them are affected by this bug. Would it be safe to say that the probability that any individual would encounter this bug is 12 / 9.2*10^18 = 1.3*10^-18?<br />
<br />
2. It is impossible to test every possible arithmetic calculation in a computer system. How would you design a testing system that evaluated a representative sample of possible arithmetic calculations?<br />
<br />
Submitted by Steve Simon<br />
<br />
==Uncertainties of Life==<br />
<br />
Statistics would be unnecessary if we lived in a strictly deterministic universe. Indeed, statistics and variability go together. Except, in journalism, where despite the decades of statistical education, the notion of variability is virtually nonexistent. A recent example may be found in an [http://hosted.ap.org/dynamic/stories/N/NEW_CANCER_DRUG?SITE=WIFON&SECTION=HOME&TEMPLATE=DEFAULT AP release] of September 26, 2007 entitled, "New Drug May Make Tumors Self-Destruct." The article refers to a presentation "at a meeting of the European Cancer Organization in Barcelona" and concerns a drug, "STA-4783, which has no effect on normal cells" while "causing tumor cells to self-destruct by overloading them with oxygen."<br />
<br />
The article states that "the drug doubled the amount of time that advanced melanoma patients survived without their cancer worsening:" average of 1.8 months vs. an average of 3.7 months. Further, the mortality statistics were an average of 7.8 months vs. an average of 12 months. We know that "28 received the standard chemotherapy" and 53 received the standard chemotherapy plus STA-4783. However, not a whisper about variation in either arm of the study.<br />
<br />
===Discussion===<br />
<br />
1.. Consider the "28" and "53" in the respective arms of the study. What does that imbalance suggest regarding dropout rates and/or randomization? <br />
<br />
2.. Assuming you are a frequentist, speculate on why there is no mention of P-Value, statistical significance or effect size. <br />
<br />
3.. The word "average" appears many times in the article. Explain why the mean or the median would be more appropriate. <br />
<br />
4.. Explain why a box plot would be very enlightening. <br />
<br />
5.. The article says "the drug doubled the amount of time that advanced melanoma patients survived without their cancer worsening." Looking at the data, how impressive is this in your eyes? That is, how do you view the "practical" significance of two extra months on average? <br />
<br />
6.. Although STA-4783 supposedly has no side effects, no mention is made of the potential cost of the drug. If it is deemed successful, speculate on what patients may have to pay for the drug.<br />
<br />
<br />
Submitted by Paul Alper<br />
<br />
==Depressed people follow a different power law distribution==<br />
[http://economist.com/science/displaystory.cfm?story_id=9861412 Something in the way he moves,] The Economist, Sep 27th 2007.<br><br />
<br />
This Economist article claims that depressed people move in a mathematically different way from other people.<br />
The paper underlying the article makes two assertions:<br />
* The durations of periods of physical activity (while resting) follow a [http://en.wikipedia.org/wiki/Power_law power law] distribution.<br />
* The resulting [http://en.wikipedia.org/wiki/Probability_distribution distributions] differ between healthy and clinically depressed people, to such an extent that this test could be used to diagnose [http://en.wikipedia.org/wiki/Clinical_depression clinical depression.]<br />
<br />
Power law distributions have been previously discussed in Chance News [http://chance.dartmouth.edu/chancewiki/index.php/Special:Search?search=%22power+law%22&go=Go on numerous occasions.]<br />
<br />
The data used to derive these conclusions <br />
consists of fourteen patients with major depressive disorder <br />
and eleven age-matched healthy control subjects.<br />
Accelerometers detected small changes in the acceleration of patients' wrists.<br />
Even slight movements of the subjects, <br />
ranging from, writing or working on a computer to physical exercise, <br />
are registered every minute for several days.<br />
The resulting data is a count per minute of the number of times the accelerometer<br />
registered a movement.<br />
<br />
[[Image:Figure1 from Universal Scaling Law in Human Behavioral Organization.JPG|frame|right|Source: part of figure 1 taken from [http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000099000013138103000001&idtype=cvips&gifs=Yes <em>Universal Scaling Law in Human Behavioral Organization,</em>] Yoshiharu Yamamoto, <em>et al,</em> Univ of Tokyo, Phys. Rev. Lett. 99, (2007).]]<br />
<br />
The attached figure, taken from the original paper, <br />
plots the raw count data over time for five days.<br />
The authors claim that these figures<br />
<blockquote><br />
show a clear circadian rest-activity cycle in the<br />
control subject, while in the patient, such a rhythmic<br />
pattern is much disrupted, reflecting the reported chronobiological<br />
abnormality in depression<br />
</blockquote><br />
In other words, the results highlight that there is a difference <br />
in the way that the healthy and the depressed spread their resting periods over the day:<br />
depressed patient shows bursts in the activity counts;<br />
control subjects are characterized by more sustained activity levels. <br />
This basic result confirmed a known feature of depressed people:<br />
<blockquote><br />
The normal daily rhythm that would lead to a high, <br />
steady number of counts during daylight hours and low counts during the night <br />
was replaced by occasional bursts of activity.<br />
</blockquote><br />
<br />
To aggregate the data over time,<br />
the authors estimated the cumulative distribution of durations <br />
of both resting periods.<br />
A resting (active) period's duration is defined as the total time <br />
that the count per minute remains below (above) some chosen threshold. <br />
<br />
The Economist claims that the surprising result in the paper is that<br />
plotting the lengths of low-activity periods against their frequency <br />
produces strikingly different patterns in healthy verses depressed people.<br />
It goes on to speculate that this discovery may provide another way of diagnosing major depression.<br />
<br />
The power-law results were only applicable for periods <br />
when patients and controls were resting. <br />
But the authors claim that results are consistent for varying choices of the threshold.<br />
In contrast, during active periods<br />
the cumulative distribution takes a 'stretched exponential form'.<br />
<br />
The authors claim:<br />
<blockquote><br />
Surprisingly, these statistical laws, <br />
after being rescaled by the mean waiting times, <br />
are not affected by altering the threshold value to calculate the waiting times. <br />
They share the distribution form for individuals considerably different<br />
in their daily living, and regardless of whether healthy or<br />
suffering from major depression, therefore <br />
suggesting the presence of universal laws governing human behavioral organization.<br />
</blockquote><br />
<br />
The Economist summarises a corollary conjectured by the authors:<br />
<blockquote><br />
(this result) also raises an interesting question about the nature of depression itself. <br />
That is because, when he looked for similar power-law curves in other areas, <br />
the one which he thought most resembled that exhibited by the depressed <br />
turned out to be the pattern of electrical activity shown by nerve cells isolated in a Petri dish <br />
and unable to contact their neighbours.<br />
<br />
It is both unnerving and intriguing that a mental disorder which isolates people from human society, <br />
and which must surely have its origins in some malfunction of the nerve cells, <br />
is reflected in the behaviour of cells that have themselves been isolated. <br />
Maybe this is just a coincidence but maybe it is not.<br />
</blockquote><br />
<br />
===Questions===<br />
* All the patients wore the accelerometer (aka activity monitor aka [http://www.theactigraph.com/?gclid=CMnUqIu8644CFRI-EAodejBUJg motion logger]) on the wrist of their non-dominant hand. Would you expect results to differ materially if the other hand, or a leg, was used? <br />
* The fourteen depressed patients wore their accelerometers for at least 18 days each, rising to 42 days in some cases. All eleven healthy controls wore their accelerometers for seven days. Does it matter that the time periods are much longer for the patients relative to the controls? <br />
** If so, how might a statistical analysis adjust for this? <br />
** Would it matter if the data from each patient was not taken from one continuous time period?<br />
** Are their enough patients in this experiment? Patients and controls were age-matched, why do you think that this was necessary? On the other hand, the sex of patients and controls is not mentioned, do you care?<br />
* The severity of depression of the patients was mild to moderate. Should the results have accounted for the degree of severity of the clinically depressed patients? <br />
** Can you map out in your mind how you might build a statistical model to do this? The objective might be a diagnostic tool for clinical depression, in which case, your model would have to be capable of distinguishing between mild (non-clinical) and chronic depression. Is the preliminary result outlined in this article sufficient to justify the time/expense of this extra work, in your view?<br />
** Do you think that the severity of a person's movements, rather than just the count of such movements per minute, is more informative? Speculate why you think this type of measurement was not recorded?<br />
* The data consists of the number of accelerometer counts per minute. Minute periods for which the count was zero were excluded from the analysis. Can you guess why the authors did this? Might it affect the results in some way?<br />
** The maximum number of counts that the accelerometer can count in one minute is 300. Is this relevant in any context?<br />
* Do you know what a '[http://en.wikipedia.org/wiki/Stretched_exponential_function stretched exponential] distribution or a [http://en.wikipedia.org/wiki/Cumulative_distribution_function#Complementary_cumulative_distribution_function complementary cumulative distribution function] is? Can you relate the former to a more commonly known distribution in statistics and do you know a more common term to describe the latter distribution? <br />
* The authors say <em>the [http://en.wikipedia.org/wiki/Kolmogorov-Smirnov_test Kolmogorov-Smirnov test] is used throughout.</em> What other tests might you like to see to distinguish patients from controls? <br />
** Do any of your tests account for the time order in which the data is recorded? If not, why not?<br />
** The authors report a p-value of 0.0001 for the different scaling exponents in the two fitted power law distributions. Does the low p-value surprise you? How does it relate to the number of people in the sample? The authors mention that this p-value is associated with a significantly longer (p < 0.001) mean resting-period duration in the patients (15 minutes) than in the control subjects (7 minutes). How might the number of patients and controls affect this statistic's p-value?<br />
** If the graph in the figure above are typical of all patients, as claimed, why would anyone bother to calculate a statistical test? Isn't it obvious that there is there is overwhelming empirical evidence from just exploring the data that the patterns in the two time series are completely different? Is there likely to be a statistical test that might show no difference between the two datasets? <br />
* Are you comfortable with the conjecture that it might be more than coincidence that electrical activity in nerve cells also follows a power law distribution?<br />
<br />
===Further reading===<br />
* [http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000099000013138103000001&idtype=cvips&gifs=Yes <em>Universal Scaling Law in Human Behavioral Organization,</em>] Yoshiharu Yamamoto, <em>et al,</em> Univ of Tokyo, Phys. Rev. Lett. 99, (2007). <br />
** This short four-page paper is currently available for free from [http://www.p.u-tokyo.ac.jp/~yamamoto/papers/prl08.pdf the author's website.]<br />
* Trivia - While browsing links related to this article - I stumbled across a [http://physicsworld.com/cws/article/news/23428/1/051015 neat graphical summary] of the numbers of letters sent and received by Darwin and Einstein over their lifetimes. The response times of both authors follow similar power law distributions (Source: [http://physicsworld.com/cws/article/news/23428/1/051015 Nature, 437, 1251).]<br />
<br />
Submitted by John Gavin.</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_30&diff=4624Chance News 302007-10-23T12:51:25Z<p>Thekohser: /* Forsooth */ Eagles in the red zone</p>
<hr />
<div>==Quotations==<br />
==Forsooth==<br />
The following Forsooth was suggested by John Vokey.<br />
<br />
<blockquote>[http://www.theglobeandmail.com/servlet/story/RTGAM.20070911.wvitamin11/BNStory/specialScienceandHealth/home Vitamin D can lower risk of death by 7 percent]<div align=right> Martin Mitttelstaedt<br> Globe and Mail<br> September 11, 2007<br> </div></blockquote><br />
<br />
This is an interesting example. In the article we read "people who were given a vitamin D supplement had a 7-per-cent lower risk of premature death than those who were not." and "It appears to be a life extender". So perhaps many of our forsooths come from the fact that copy editors write the headlines. (Lauie Snell)<br />
<br />
The following Forsooth was suggested by Gregory Kohs.<br />
<br />
<blockquote>[http://philly.metro.us/metro/sports/article/Birds_fall_in_heartbreaker/10429.html Birds fall in heartbreaker]<div align=right> Andy Jasner<br> Metro<br> October 22, 2007<br> </div></blockquote><br />
<br />
''The <nowiki>[Philadelphia]</nowiki> Eagles’ problems in the red zone finally appeared to have been fixed when Donovan McNabb connected with tight end Matt Schobel for a 13-yard score with 4:57 left. It was the Eagles’ first touchdown in four trips inside the 20 during yesterday’s game. Entering the contest, the Eagles had scored just five touchdowns in 16 possessions in the red zone.''<br />
<br />
Note that prior to the game against the Bears, the Eagles had a 31.25% touchdown rate inside the 20-yard line. Note that this "problem" appeared to be fixed by a game with a 25% red zone touchdown rate.<br />
<br />
==Supplement may help treat gambling addiction==<br />
[http://www.startribune.com/1244/story/1416861.html Miniapolis Star Tribune], September 12, 2007<br><br />
Maura Lerner<br />
<br />
There seems to be a never-ending supply of questionable statistical studies. Consider the recent Minneapolis Star Tribune account of September 12, 2007. A University of Minnesota researcher publishing in the September 15, 2007 issue of Biological Psychiatry treated "27 pathological gamblers for eight weeks" with an amino acid supplement, N-acetyl cysteine. "By the end, 60 percent said they had fewer urges to gamble." Of the 16 who reported a benefit, "13 remained in a follow-up study...five out the six on the supplement reported continued improvement, compared to two out of seven on a placebo." According to the researcher, "There does seem to be some effect, but you would need bigger numbers."<br />
<br />
Here are the results of the follow-up study as seen by Minitab:<br />
<br />
MTB > PTwo 6 5 7 2.<br />
<br />
Test and CI for Two Proportions <br />
<br />
<table width="49%" border="1"><br />
<tr> <br />
<td width="33%"><div align="center">Sample</div></td><br />
<td width="13%"><div align="center">X</div></td><br />
<td width="12%"><div align="center">N</div></td><br />
<td width="42%"><div align="center">Sample p</div></td><br />
</tr><br />
<tr> <br />
<td><div align="center">1</div></td><br />
<td><div align="center">5</div></td><br />
<td><div align="center">6</div></td><br />
<td><div align="center">0.833333</div></td><br />
</tr><br />
<tr> <br />
<td><div align="center">2</div></td><br />
<td><div align="center">2</div></td><br />
<td><div align="center">7</div></td><br />
<td><div align="center">0.285714</div></td><br />
</tr><br />
</table><br />
Difference = p (1) - p (2) <br><br />
<br />
Estimate for difference: 0.547619<br><br />
<br />
95% CI for difference: (0.0993797, 0.995858)<br><br />
<br />
Test for difference = 0 (vs not = 0): Z = 2.39 P-Value = 0.017<br><br />
<br />
Fisher's exact test: P-Value = 0.103<br><br />
<br />
NOTE: The normal approximation may be inaccurate for small samples.<br />
<br />
===Discussion===<br />
1.. Assume you are a frequentist, what about statistical significance? Note the discrepancy between the exact P-Value and the P-Value using the normal approximation.<br />
<br />
2.. Assume you are a Bayesian and thus immune to P-Value whether exact or due to a normal approximation, pick your priors and find the probability that there is a difference between the effect of the supplement and the effect of the placebo. <br />
<br />
3.. Aside from the choice of inference procedure, frequentist or Bayesian, what other flaws do you see in this study with regard to sample size and measurement of success?<br />
<br />
4.. Speculate as to why this study was reported in a Twin Cities newspaper and probably not elsewhere. <br />
<br />
5.. Speculate on what might happen if the 11 who did not respond to the supplement originally were put on the follow-up study.<br />
<br />
Submitted by Paul Alper<br />
<br />
==Excel 2007 arithmetic error==<br />
<br />
[http://blogs.msdn.com/excel/archive/2007/09/25/calculation-issue-update.aspx Calculation Issue Update] David Gainer, September 25, 2007.<br />
<br />
The Excel blog at Microsoft usually talks about product enhancements and future plans for development, but on September 25 had to admit an embarrassing problem with basic arithmetic in Excel 2007. A series of calculations such as 77.1*850, 20.4*3,212.5, 10.2*6,425, and 5.1*12,850 that should normally produce a value of 65,535 instead produce a result of 100,000. The result is actually stored in an acceptable binary form, but flaw occurs in the process of transforming the binary representation to a decimal form for display.<br />
<br />
Although there are an infinite number of rational numbers, a computer can only represent a finite number of these values in its storage. For the rest, the computer has to choose a value in binary that is reasonably close. Some numbers that have very simple representations in decimal, such as 0.1 do not have an exact representation in binary. Certain fractions, such as 1/3 and 1/7 have infinite expansions in decimal notation and have to be truncated. A larger list of fractions such as 1/10 have infinite expansion in binary representation, so that creates a slight inaccuracy. This slight inaccuracy produces a product for terms like 77.1*850 that are not quite 65,535 but slightly larger or smaller.<br />
<br />
According to the Microsoft blog, there are six binary numbers that lie between the decimal values of 65534.99999999995 and 65,535 that are not displayed properly in Excel 2007. Another six binary numbers that lie between 65,535.99999999995 and 65,536 also have problems. You can't enter these numbers directly in Excel, because Excel will round any directly entered values to 15 significant digits.<br />
<br />
It's probably not a coincidence that these numbers are close to 2^16. These values would have long strings of consecutive 1's in the binary representation. An entry on the Wolfram Blog, [http://blog.wolfram.com/2007/09/arithmetic_is_hardto_get_right.html?lid=perma Arithmetic is Hard--To Get Right, Mark Sofroniou], speculates that there is a problem with propagation of carries.<br />
<br />
This bug only affects values close to 65,535 and 65,536 when they are displayed as a final result. Intermediate calculations that produce one of these unfortunate 12 numbers are unaffected because it is the process of converting the binary representation to a decimal form for display that is flawed.<br />
<br />
The bug also does not appear to affect earlier versions of Excel. This error is reminiscent of the [http://en.wikipedia.org/wiki/Pentium_FDIV_bug Pentium FDIV bug].<br />
<br />
===Questions===<br />
<br />
1. According to the Microsoft blog, there are 9.2*10^18 possible binary values, and only 12 of them are affected by this bug. Would it be safe to say that the probability that any individual would encounter this bug is 12 / 9.2*10^18 = 1.3*10^-18?<br />
<br />
2. It is impossible to test every possible arithmetic calculation in a computer system. How would you design a testing system that evaluated a representative sample of possible arithmetic calculations?<br />
<br />
Submitted by Steve Simon<br />
<br />
==Uncertainties of Life==<br />
<br />
Statistics would be unnecessary if we lived in a strictly deterministic universe. Indeed, statistics and variability go together. Except, in journalism, where despite the decades of statistical education, the notion of variability is virtually nonexistent. A recent example may be found in an [http://hosted.ap.org/dynamic/stories/N/NEW_CANCER_DRUG?SITE=WIFON&SECTION=HOME&TEMPLATE=DEFAULT AP release] of September 26, 2007 entitled, "New Drug May Make Tumors Self-Destruct." The article refers to a presentation "at a meeting of the European Cancer Organization in Barcelona" and concerns a drug, "STA-4783, which has no effect on normal cells" while "causing tumor cells to self-destruct by overloading them with oxygen."<br />
<br />
The article states that "the drug doubled the amount of time that advanced melanoma patients survived without their cancer worsening:" average of 1.8 months vs. an average of 3.7 months. Further, the mortality statistics were an average of 7.8 months vs. an average of 12 months. We know that "28 received the standard chemotherapy" and 53 received the standard chemotherapy plus STA-4783. However, not a whisper about variation in either arm of the study.<br />
<br />
===Discussion===<br />
<br />
1.. Consider the "28" and "53" in the respective arms of the study. What does that imbalance suggest regarding dropout rates and/or randomization? <br />
<br />
2.. Assuming you are a frequentist, speculate on why there is no mention of P-Value, statistical significance or effect size. <br />
<br />
3.. The word "average" appears many times in the article. Explain why the mean or the median would be more appropriate. <br />
<br />
4.. Explain why a box plot would be very enlightening. <br />
<br />
5.. The article says "the drug doubled the amount of time that advanced melanoma patients survived without their cancer worsening." Looking at the data, how impressive is this in your eyes? That is, how do you view the "practical" significance of two extra months on average? <br />
<br />
6.. Although STA-4783 supposedly has no side effects, no mention is made of the potential cost of the drug. If it is deemed successful, speculate on what patients may have to pay for the drug.<br />
<br />
<br />
Submitted by Paul Alper<br />
<br />
==Depressed people follow a different power law distribution==<br />
[http://economist.com/science/displaystory.cfm?story_id=9861412 Something in the way he moves,] The Economist, Sep 27th 2007.<br><br />
<br />
This Economist article claims that depressed people move in a mathematically different way from other people.<br />
The paper underlying the article makes two assertions:<br />
* The durations of periods of physical activity (while resting) follow a [http://en.wikipedia.org/wiki/Power_law power law] distribution.<br />
* The resulting [http://en.wikipedia.org/wiki/Probability_distribution distributions] differ between healthy and clinically depressed people, to such an extent that this test could be used to diagnose [http://en.wikipedia.org/wiki/Clinical_depression clinical depression.]<br />
<br />
Power law distributions have been previously discussed in Chance News [http://chance.dartmouth.edu/chancewiki/index.php/Special:Search?search=%22power+law%22&go=Go on numerous occasions.]<br />
<br />
The data used to derive these conclusions <br />
consists of fourteen patients with major depressive disorder <br />
and eleven age-matched healthy control subjects.<br />
Accelerometers detected small changes in the acceleration of patients' wrists.<br />
Even slight movements of the subjects, <br />
ranging from, writing or working on a computer to physical exercise, <br />
are registered every minute for several days.<br />
The resulting data is a count per minute of the number of times the accelerometer<br />
registered a movement.<br />
<br />
[[Image:Figure1 from Universal Scaling Law in Human Behavioral Organization.JPG|frame|right|Source: part of figure 1 taken from [http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000099000013138103000001&idtype=cvips&gifs=Yes <em>Universal Scaling Law in Human Behavioral Organization,</em>] Yoshiharu Yamamoto, <em>et al,</em> Univ of Tokyo, Phys. Rev. Lett. 99, (2007).]]<br />
<br />
The attached figure, taken from the original paper, <br />
plots the raw count data over time for five days.<br />
The authors claim that these figures<br />
<blockquote><br />
show a clear circadian rest-activity cycle in the<br />
control subject, while in the patient, such a rhythmic<br />
pattern is much disrupted, reflecting the reported chronobiological<br />
abnormality in depression<br />
</blockquote><br />
In other words, the results highlight that there is a difference <br />
in the way that the healthy and the depressed spread their resting periods over the day:<br />
depressed patient shows bursts in the activity counts;<br />
control subjects are characterized by more sustained activity levels. <br />
This basic result confirmed a known feature of depressed people:<br />
<blockquote><br />
The normal daily rhythm that would lead to a high, <br />
steady number of counts during daylight hours and low counts during the night <br />
was replaced by occasional bursts of activity.<br />
</blockquote><br />
<br />
To aggregate the data over time,<br />
the authors estimated the cumulative distribution of durations <br />
of both resting periods.<br />
A resting (active) period's duration is defined as the total time <br />
that the count per minute remains below (above) some chosen threshold. <br />
<br />
The Economist claims that the surprising result in the paper is that<br />
plotting the lengths of low-activity periods against their frequency <br />
produces strikingly different patterns in healthy verses depressed people.<br />
It goes on to speculate that this discovery may provide another way of diagnosing major depression.<br />
<br />
The power-law results were only applicable for periods <br />
when patients and controls were resting. <br />
But the authors claim that results are consistent for varying choices of the threshold.<br />
In contrast, during active periods<br />
the cumulative distribution takes a 'stretched exponential form'.<br />
<br />
The authors claim:<br />
<blockquote><br />
Surprisingly, these statistical laws, <br />
after being rescaled by the mean waiting times, <br />
are not affected by altering the threshold value to calculate the waiting times. <br />
They share the distribution form for individuals considerably different<br />
in their daily living, and regardless of whether healthy or<br />
suffering from major depression, therefore <br />
suggesting the presence of universal laws governing human behavioral organization.<br />
</blockquote><br />
<br />
The Economist summarises a corollary conjectured by the authors:<br />
<blockquote><br />
(this result) also raises an interesting question about the nature of depression itself. <br />
That is because, when he looked for similar power-law curves in other areas, <br />
the one which he thought most resembled that exhibited by the depressed <br />
turned out to be the pattern of electrical activity shown by nerve cells isolated in a Petri dish <br />
and unable to contact their neighbours.<br />
<br />
It is both unnerving and intriguing that a mental disorder which isolates people from human society, <br />
and which must surely have its origins in some malfunction of the nerve cells, <br />
is reflected in the behaviour of cells that have themselves been isolated. <br />
Maybe this is just a coincidence but maybe it is not.<br />
</blockquote><br />
<br />
===Questions===<br />
* All the patients wore the accelerometer (aka activity monitor aka [http://www.theactigraph.com/?gclid=CMnUqIu8644CFRI-EAodejBUJg motion logger]) on the wrist of their non-dominant hand. Would you expect results to differ materially if the other hand, or a leg, was used? <br />
* The fourteen depressed patients wore their accelerometers for at least 18 days each, rising to 42 days in some cases. All eleven healthy controls wore their accelerometers for seven days. Does it matter that the time periods are much longer for the patients relative to the controls? <br />
** If so, how might a statistical analysis adjust for this? <br />
** Would it matter if the data from each patient was not taken from one continuous time period?<br />
** Are their enough patients in this experiment? Patients and controls were age-matched, why do you think that this was necessary? On the other hand, the sex of patients and controls is not mentioned, do you care?<br />
* The severity of depression of the patients was mild to moderate. Should the results have accounted for the degree of severity of the clinically depressed patients? <br />
** Can you map out in your mind how you might build a statistical model to do this? The objective might be a diagnostic tool for clinical depression, in which case, your model would have to be capable of distinguishing between mild (non-clinical) and chronic depression. Is the preliminary result outlined in this article sufficient to justify the time/expense of this extra work, in your view?<br />
** Do you think that the severity of a person's movements, rather than just the count of such movements per minute, is more informative? Speculate why you think this type of measurement was not recorded?<br />
* The data consists of the number of accelerometer counts per minute. Minute periods for which the count was zero were excluded from the analysis. Can you guess why the authors did this? Might it affect the results in some way?<br />
** The maximum number of counts that the accelerometer can count in one minute is 300. Is this relevant in any context?<br />
* Do you know what a '[http://en.wikipedia.org/wiki/Stretched_exponential_function stretched exponential] distribution or a [http://en.wikipedia.org/wiki/Cumulative_distribution_function#Complementary_cumulative_distribution_function complementary cumulative distribution function] is? Can you relate the former to a more commonly known distribution in statistics and do you know a more common term to describe the latter distribution? <br />
* The authors say <em>the [http://en.wikipedia.org/wiki/Kolmogorov-Smirnov_test Kolmogorov-Smirnov test] is used throughout.</em> What other tests might you like to see to distinguish patients from controls? <br />
** Do any of your tests account for the time order in which the data is recorded? If not, why not?<br />
** The authors report a p-value of 0.0001 for the different scaling exponents in the two fitted power law distributions. Does the low p-value surprise you? How does it relate to the number of people in the sample? The authors mention that this p-value is associated with a significantly longer (p < 0.001) mean resting-period duration in the patients (15 minutes) than in the control subjects (7 minutes). How might the number of patients and controls affect this statistic's p-value?<br />
** If the graph in the figure above are typical of all patients, as claimed, why would anyone bother to calculate a statistical test? Isn't it obvious that there is there is overwhelming empirical evidence from just exploring the data that the patterns in the two time series are completely different? Is there likely to be a statistical test that might show no difference between the two datasets? <br />
* Are you comfortable with the conjecture that it might be more than coincidence that electrical activity in nerve cells also follows a power law distribution?<br />
<br />
===Further reading===<br />
* [http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000099000013138103000001&idtype=cvips&gifs=Yes <em>Universal Scaling Law in Human Behavioral Organization,</em>] Yoshiharu Yamamoto, <em>et al,</em> Univ of Tokyo, Phys. Rev. Lett. 99, (2007). <br />
** This short four-page paper is currently available for free from [http://www.p.u-tokyo.ac.jp/~yamamoto/papers/prl08.pdf the author's website.]<br />
* Trivia - While browsing links related to this article - I stumbled across a [http://physicsworld.com/cws/article/news/23428/1/051015 neat graphical summary] of the numbers of letters sent and received by Darwin and Einstein over their lifetimes. The response times of both authors follow similar power law distributions (Source: [http://physicsworld.com/cws/article/news/23428/1/051015 Nature, 437, 1251).]<br />
<br />
Submitted by John Gavin.</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_16&diff=2433Chance News 162006-04-23T17:53:41Z<p>Thekohser: /* Forsooth */</p>
<hr />
<div>==Quotation==<br />
<blockquote>It is as useless to debate whether an actual sequence of coin tossing was governed by the laws of probability as "to debate the table manners of children with six arms."<br><br />
<div align="right" >Joe Doob<br><br />
''Chances are'', Michael Kaplan and Ellen Kaplan </div></blockquote><br />
<br />
Here's more from Doob on this subject:<br />
<br />
<blockquote> Then and later the most embarrassing probability class lecture was the first, in which I tried to give a satisfying account of what happens when one tosses a coin. (A famous statistician told me that he solves the difficulty by never mentioning the context.) One wants to talk about a limit of a frequency, but "limit" has no meaning unless an infinite sequence is involved, and an infinite sequence is not an empirical concept. I made vague and heavily hedged remarks such as that the ratio I would like to have limit l/2 "seems to tend to 1/2", that the coin tosser "would be very much surprised if the ratio is not nearly 1/2 after a large number of tosses", and so on.<br><br><br />
<br />
The students never seemed to be bothered by my vagueness. For that matter professionals who write about the subject are usually also unbothered, perhaps because they never seem to be tossing real coins in a real world under the influence of Newton's laws, which somehow are not mentioned in the writing. </blockquote><br />
<br />
<div align="right" >A conversation with Joe Doob<br><br />
Statist. Sci. 12, no. 4 (1997), 301–311</div><br />
<br />
Submitted by Laurie Snell<br />
<br />
==Forsooth==<br />
<br />
Here are three Forsooths from the April 2006 RSS News.<br />
<br />
<blockquote> <br />
HIV patients in low socio-eonomic classes are 89 per cent more likely to die than better-off people with the infection, claims a study of 2684 adults in the ''Journal of Health Care for the Poor and Undeserved'' (Nov).<br><br />
<div align="right">''The Times''<br><br />
8 November 2005<br />
</div></blockquote><br />
<br />
<blockquote> <br />
A ten-year study of men in Wales found that those who had sex twice or more a week were 50% less likely to have died than those who had it less than once a month.<br><br />
<div align="right">''Metro''<br><br />
1 February 2006<br />
</div></blockquote><br />
<br />
<blockquote> <br />
A Malaysian man was speechless when he received a $218 trillion phone bill and was ordered to pay up within 10 days or face prosecution... It wasn't clear whether the bill was a mistake...<br />
<div align="right">''Associated Press''<br><br />
http://www.usatoday.com/news/offbeat/2006-04-10-malaysia_x.htm<br />
11 April 2006<br />
</div></blockquote><br />
<br />
==Exponential decay in Biblical ages==<br />
[http://www.biblestudy.org/basicart/longpatr.html WHY did people live longer BEFORE Noah's Flood than they did after it?] written by Arnold C. Mendez, Sr. and published at BibleStudy.org.<br />
<br />
While looking on the web for good examples of the coefficient of determination, I came across a statistical analysis of the ages of Biblical patriachs. Apparently the author believes in a literal interpretation of the Bible and wants to answer skeptical comments about the unusual ages reported for some of the patriarchs in the Bible.<br />
<br />
<blockquote>"One of the most intriguing facts in the Bible is the immense life spans of the patriarchs before and just after the flood. Adam lived 930 years, Methuselah the longest lived of the patriarchs lived 969 years. Noah lived 950 years."</blockquote><br />
<br />
Why is it that no one today lives so long?<br />
<br />
<blockquote>"After the flood the earth was completely different than the earth before. There were widespread global differences. These would include changes in the climate, composition of the atmosphere, hydrologic cycle, geologic features, cosmic radiation reaching the earth, ozone concentration, ultra violet light, background radiation, genetics, diet, and a host of other subtle and/or profound chemical and physiological changes. These changes caused a rapid decline of the longevity of post flood humanity."</blockquote><br />
<br />
The statistical model comes in the analysis of the decline in ages after the flood. An exponential decay model produces the following equation y=487.78exp(-0.0907x) where x represents the generation number. After 20 generations, the ages settles down to a more modern figure of 70 years. The coefficient of determination is 0.889.<br />
<br />
<blockquote>"This means that the decay rate of the patriarch's death after the flood was only 11% from being a perfect match."</blockquote><br />
<br />
You can view a graph of the data and the fitted line below, taken directly from the article.<br />
<br />
http://www.biblestudy.org/basicart/longflod.gif<br />
<br />
The author argues that the ages must be genuine since they fit an exponential curve so well and the writers of the time would not have the mathematical sophistication to fake an exponential decay curve.<br />
<br />
===Questions===<br />
1. Does a coefficient of determination of 89% sound impressive to you? What do you think about the author's comment that this is "only 11% from being a perfect match"?<br />
<br />
2. What other models (linear or non-linear) would be worth considering for this data?<br />
<br />
3. Is there an alternative explanation for this pattern of ages?<br />
<br />
Submitted by Steve Simon<br />
<br />
<br />
==Is Jerry Falwell's debate team really number 1 in the nation?==<br />
Adapted from [http://abcnews.go.com/Technology/print?id=1786422 Who's Counting: Distrusting Atheists] <br />
<br />
The NY Times Magazine, Newsweek, and 60 Minutes are three of the media outlets devoting considerable attention to the "national champion" debate team from conservative fundamentalist Jerry Falwell's Liberty University. But does the team deserve this number one ranking or is it bogus, an artifact of the way the so-called overall category <br />
<br />
As bloggers Jim Hanas, Ed Brayton and others have observed (and as is briefly and unobtrusively buried in the Times article itself), the ranking is based on the performance of the team in all tournaments, including novice and junior varsity contests.<br />
<br />
The way rankings are determined in the "overall" category, winning at any of these second-tier tournaments adds to the team's point total. Liberty, which has a broad-based program, enters many of them and racks up many of its points by doing so.<br />
<br />
The schools with the top individual teams, however, often don't have novice or JV teams and usually don't enter many of the lesser tournaments.<br />
<br />
Even with such extensive, but light opposition, and the points resulting from it, the Liberty varsity team seldom reaches the semifinals and has yet to win a single varsity tournament.<br />
<br />
In fact, in the varsity rankings Liberty is 20th, not first, and, when the quality of its opponents is taken into account, it ranks even lower than that.<br />
<br />
As Hanas remarks, referring to Liberty as the No. 1 team and one of the nation's great collegiate debate programs is a bit "like calling the best Division III basketball team the NCAA champion."<br />
<br />
Another analogy is to the brief 1992 presidential campaign of Iowa Sen. Tom Harkin. He was way behind in the primaries, but some of his staffers jokingly suggested that their man was leading. In winning Minnesota, Iowa and Montana, they argued that he had captured the largest land mass of any of the contenders.<br />
<br />
Submitted by John A. Paulos<br />
<br />
==Does a glass of wine a day keep the doctor away?==<br />
<br />
[http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2006/03/30/MNGMTI0B3U1.DTL UCSF points out flaw in studies tying alcohol to heart health.]<br><br />
''San Francisco Chronicle'', March 30, 2006<br><br />
Sabine Russell<br />
<br />
[http://www.journalsonline.tandf.co.uk/link.asp?id=m350jp7v218202g8 Moderate alcohol use and reduced mortality risk: Systematic error in prospective studies], Kaye M. Fillmore et al, ''Addiction Research and Theory'', March 30, 2006.<br />
<br />
A large numbers of observational studies have suggested that moderate drinkers have a lower risk for heart attacks than nondrinkers or heavy drinkers. The results of these studies are usually illustrated by a U shaped graphic like this:<br />
<br />
<center>[[Image:wine1.jpg|500px|]]<br />
</center><br />
<br />
This graphic is from the article "Alcohol and Mortality in British Men; Explaining the U-Shaped Curve", ''The Lancet'', December 3, 1988, A. Shaper, et al. <br />
<br />
In their summary the authors wrote:<br />
<br />
<blockquote>In a prospective study of 7735 middle-aged British men, 504 of whom died in a follow-up period of 7.5 years, there was a U-shaped relationship between alcohol intake and total mortality and an inverse relationship with cardiovascular mortality, even after adjustment for age, cigarette smoking, and social class. These mortality patterns were seen in all smoking categories (with ex-smoking non-drinkers having the highest mortality) and were observed in manual but not in non-manual workers. The alcohol-mortality relationships are produced by pre-existing disease and by the movement of men with such disease into non-drinking or occasional-drinking categories. The concept of a "protective” effect of drinking on mortality, ignoring the dynamic relationship between ill-health and drinking behavior, is likely to be ill founded.</blockquote?><br />
<br />
The authors are concerned that this and other similar studies are seriously flawed because they include subjects who have recently quit drinking and who are typically older people with medical problems who are told by their doctors to quit drinking. They suggest that this could explain why those who don't drink have a higher mortality rate than moderate drinkers. Evidently this concern was not pursued until a recent study of Kaye Fillmore and her colleagues to appear om the mext issue of the journal ''Addiction Research and Theory.''<br />
<br />
The ''Chronicle'' article described the new study as follows:<br />
<br />
<blockquote>Fillmore and colleagues from the University of Victoria, British Columbia; and Curtin University, in Perth, Australia, analyzed 54 different studies examining the relationship between light to moderate drinking and health. Of these, only seven did not inappropriately mingle former drinkers and abstainers.<br><br> <br />
<br />
All seven of those studies found no significant differences in the health of those who drank -- or previously drank -- and those who never touched the stuff. The remaining 47 studies represent the body of research that has led to a general scientific consensus that moderate drinking has a health benefit. </blockquote><br />
<br />
The article quotes Dr. Tim Naimi at the Centers for Disease Control as saying "The whole field of 'moderate drinking' studies is deeply flawed" and goes on to say:<br />
<br />
<blockquote> In a study published in May 2005 in the ''American Journal of Preventive Medicine'', Naimi and other CDC colleagues found that the comparatively higher risk of heart disease in abstainers could be explained by socioeconomic factors rather than lack of protection from alcohol consumption. Non-drinkers, for example, tended to be poorer than drinkers, had less access to health care, and had less healthy diets.</blockquote><br />
<br />
Note that in the 1988 article, Shaper and his colleagues were also concerned about difference in drinking habits of different groups, in particular manual and non-manual workers. <br />
<br />
Naimi says, "Anyone who suggests that people should begin drinking, or drink more frequently, to reduce the risk of heart disease is misguided".<br />
<br />
However, the UCSF [http://pub.ucsf.edu/newsservices/releases/200603277/ news release] for the study by Fillmore and her colleagues suggests that there might still be hope for us:<br />
<br />
<blockquote> The authors caution that their report, published online in advance of the May 2006 issue of Addiction Research and Theory, has not disproved the notion that light drinking is good for health, as too few error-free studies have been performed. They suggest, however, that the extent to which these benefits actually translate into longer life may have been exaggerated.</blockquote><br />
<br />
===DISCUSSION===<br />
<br />
(1) The chronicle quotes Dr. Arthur Klatsy, a well-known researcher on the benefits of moderate drinking:<br />
<br />
<blockquote> There are inherent weaknesses in all the epidemiological studies of alcohol and heart health. What is needed is a randomized trial in which a group is assigned to consume one or two drinks a day and another abstains, and their comparative health is assessed over a period of years. </blockquote><br />
<br />
Do you think it would be possible to carry out such a study?<br />
<br />
Submitted by Laurie Snell<br />
<br />
==Hierarchy Reversal==<br />
<br />
[http://www.washingtonpost.com/wp-dyn/content/article/2006/04/11/AR2006041101478.html Comparison of schizophrenia drugs often favors firm funding study].<br><br />
''Washington Post'', April 12, 2006; Page A01<br><br />
Shanker Vedantam<br />
<br />
Most statistics textbooks would claim an experiment is superior to an observational study which in turn is better than mere anecdotal evidence. And the best experiment is a double-blind clinical trial. Well, perhaps not according to Shankar Vedantam's article in the Washington Post of April 12, 2006. The deputy editor of JAMA, Drummond Rennie, says "There will be two classes of [clinical] trials--the believable ones and the non-believable ones." The latter are represented by those which are sponsored by the members of the pharmaceutical industry. <br />
<br />
As John Davis put it in the American Journal of Psychiatry, "On the basis of these contrasting findings in head-to-head trials, it appears that whichever company sponsors the trial produces the better antipsychotic drug." Vedantam writes, "Other experts note that industry studies invariably seek to boost the image of expensive drugs that are still under patent. Moreover, they say, the trials are relatively brief and test drugs on patients with simpler problems than doctors typically encounter in daily practice." Turns out that "cheaper drugs not under patent" were superior to the expensive drugs when the federal government did the testing,<br />
<br />
In addition, industry studies can be "misleading in multiple ways," including testing "too low a dose of a competitor's drug." Although not mentioned in the article, I suspect that another way to mislead is to have too high a dose of the competitor's drug, thus increasing the severity and the number of side effects. Then, of course, there is the tried and true practice of deep-sixing a test which comes out the wrong way (aka as the "file drawer" technique).<br />
<br />
Unfortunately, the justified cynicism runs deeper. Davis, "joked in an interview that he no longer gets to fly first class to Tokyo and Monte Carlo since he stopped accepting money from pharmaceutical companies." He "guessed that 90 percent of industry-sponsored studies that boast a prominent academic as the lead author are conducted by a company that later enlists a university researcher as the 'author'." Rennie goes even further concerning so-called author-shopping: "We know that happens all the time. The only reason that the company wants a non-company person as an author is to give credence to an advertisement...The whole entire paper from start to finish is an advertisement."<br />
<br />
While the discussion focused on antipsychotic drugs, it not beyond imagination that similar advertisements posing as research clinical trials take place more generally. Consequently, perhaps the first question to ask of any statistical study is: Who is doing the funding? <br />
<br />
===DISCUSSION===<br />
<br />
1. Why do statistics textbooks claim an experiment is superior to an observational study which in turn is better than anecdotal evidence? And why is the best experiment a double-blind clinical trial?<br />
<br />
2. Would author-shopping be more prevalent in pharmaceutical studies than elsewhere?<br />
<br />
3. The director of the National Institute of Mental Health, Thomas R. Insel, claims, "The publc is less interested in statistical significance and more interested in clinical significance." If so, why is a statistician needed?<br />
<br />
===RELATED ARTICLE===<br />
[http://www.intelihealth.com/IH/ihtIH/WSIHW000/8271/8014/465506.html Study: Medical manual's authors often tied to drugmakers.]<BR><br />
''USA TODAY'', April 20, 2006<br />
<br />
Submitted by Paul Alper</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_14&diff=2254Chance News 142006-02-28T21:25:13Z<p>Thekohser: /* More medical studies the conflict with previous studies */</p>
<hr />
<div>==Quotation== <br />
<blockquote>The [Supreme] Court concluded that mental health professionals' predictions were "not always wrong...only most of the time."</blockquote><br />
<div align="right">Gerd Gigerenzer <br><br />
</div><br />
<br />
==Forsooth==<br />
<br />
<br />
<br />
<blockquote> In theory, if you were to buy 50 tickets and your neighbor bought one, neither of you would have a better or worse chance of winning, We like to say it only takes one ticket to win."<br />
</blockquote><br />
<br />
<div align="right">Brian Rockey, a spokesman for the Nebraska Lottery<br><br />
in a discussion of the record Powerball jackpot of 360 million dollars.<br><br />
Omaha World-Herald (Nebraska) February 18, 2007 Pg. 01A. </div><br />
----<br />
Who do we believe?<br />
<br />
"Two widely used nutritional supplements for arthritis pain do not effectively soothe patients' aching arthritic knees, a large federal study has found."<br />
--NYT, February 23, 2006<br />
<br />
"A combination of the popular dietary supplements glucosamine and chondroitin sulfate appears to relieve knee pain associated with moderate-to-severe arthritis, according to a large federally funded study."<br />
--WSJ, February 23, 2006<br />
----<br />
"No effect was found for glucosamine, chondroitin or a combination of the two."<br />
--NYT<br />
<br />
"Patients who had more pain did seem to be helped by the combination."<br />
--Dr. Daniel Clegg, lead author of the study<br />
----<br />
"It's a null trial. It doesn't work any better than placebo."<br />
--Dr. David Felson, a Boston University rheumatologist<br />
<br />
"I am going to continue doing it."<br />
--Nancy MacLeod, a user of the supplement<br />
----<br />
"This is a spurious subset result if I've ever seen one. I wouldn't spend a nickel trying to confirm it."<br />
--Dr. Donald Berry, M.D. Anderson Cancer Center<br />
<br />
"If I had severe pain from osteoarthritis of the knee, based on this study, I would try glucosamine and chondroitin sulfate."<br />
--Dr. M. Elizabeth Halloran, biostatistics professor at the Fred Hutchinson Cancer Research Center and the University of Washington<br />
----<br />
"Dr. Halloran said she was swayed not only by the data but also by her sister's experience giving the supplements to her arthritic dog."<br />
-- NYT, February 23, 2006<br />
<br />
"But, arthritis researchers say, they know of no biological reason why eating those compounds would help people with arthritis."<br />
-- NYT, February 23, 2006<br />
----<br />
Submitted by Paul Alper.<br />
<br />
==Gerd Gigerenzer's Calculated Risks Revisited==<br />
[http://www.dartmouth.edu/%7Echance/chance_news/recent_news/chance_news_11.03.html#item10 Chance News 11.03] had a lengthy and very positive review of Gerd Gigerenzer's book '''Calculated Risks: How To Know When Numbers Deceive You'''.<br />
Readers are urged to download that excellent review because of the information contained. However, the book is so good and so persuasive that it is worth another look in order to alert readers to some other aspects of the book and how it relates to subsequent events.<br />
<br />
The aforementioned review did not mention the abundant number of actual, real-world incidents cited in which doctors, lawyers and social workers, not to mention patients, clients and jurors, were unable to unscramble the difference between P(X| Y) and P(Y| X). Also not mentioned was Gigerenzer's dim view of screening for breast cancer and prostate cancer. Screening may be defined, according to H. Gilbert Welch, as "the systematic examination of asymptomatic people to detect and treat disease." See [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_12#Screening Chance News 12] for a review of Welch's 2004 book '''Should I Be Tested For Cancer? Maybe Not And Here's Why'''. Welch echoes and amplifies Gigerenzer contention that (mass) screening is counterproductive, especially when there is little evidence that a cure exists. Just to complicate matters, however, see [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_8#Mammograms_Validated_as_Key_in_Cancer_Fight "Mammograms validated as key in cancer fight"] in Chance News 8 which indicates that mammography screening does reduce the death rate of breast cancer, . Unfortunately, the article in the ''New England Journal of Medicine'' referred to does not explain why mammogram screening is deemed responsible for 28 to 65% of the 24% drop in the breast cancer death rate.<br />
Gigerenzer would prefer, and this is one of his main points, that any statistical data be given in counts rather than in percentages, especially percentages without a base rate, such as relative risk which he views as the most misleading. <br />
<center><table width="100%" border="1"><br />
<tr><br />
<th>Treatment</th><br />
<th>Deaths per 1000 women</th> <br />
<tr><br />
<td>No mammography screening</td><br />
<th>4</th><br />
</tr><br />
<tr><br />
<td>Mammography screening</td><br />
<th>3</th><br />
</tr><br />
</table></center><br />
<br />
Consequently, there is "a 25 percent relative risk reduction." He would prefer focusing on the difference in the number of deaths which yields the more revealing and perhaps more honest statement: "The absolute risk reduction is 4 minus 3, that is, 1 out of 1000 women (which corresponds to .1 percent)." However, "Counting on their clients' innumeracy, organizations that want to impress upon clients the benefits of treatment generally report them in terms of relative risk reduction...applicants [for grants] often feel compelled to report relative risk reductions because they sound more impressive." Although he did not use this example, one's relative "risk" of winning the lottery is infinitely greater if one buys a ticket, yet one's absolute "risk" of winning has hardly improved at all.<br />
<br />
Most of his numerical examples are typified by his discussion of the cartoon given below <br />
<br />
<center>[[Image:gigerenzer1.gif|500px]]</center><br />
<br />
which indicates the superiority of dealing with counts. Note that "H" represents having the disease and "D" represents a diagnosis having the symptom as seen by testing positive. Characteristically, there is a large number in the population who do not have the disease and because of the possibility of a wrong classification, the number of false positives (99) outweighs the number of true positives (8) resulting in P(disease| symptom) being much lower (8/(8+99)) than P(symptom| disease) (.8). This type of result, low probability of disease given symptom, is true even when ".8" is replaced by a number much closer to 1 provided there are many more who do not have the disease.<br />
<br />
Here is an example he did not consider but it also illustrates the superiority of dealing with counts. Instead of two populations--diseased and healthy--which are greatly different in size, consider Boys and Girls and the desire to predict gender based on some simple test. Assume that 50% of births are Boys so that P(Boy) = P(Girl) = 1/2. A simple, inexpensive, non-invasive gender-testing procedure indicates that it is "perfect" for boys, P(Test Boy| Boy) = 1, implying P(Test Girl| Boy) = 0. Unfortunately, this simple, inexpensive, non-invasive gender-testing procedure for girls is a "coin toss," P(Test Girl| Girl) = P(Test Boy| Girl) = 1/2. Application of Bayes theorem yields what seems to be a strange inversion, P(Boy| Test Boy) = 2/3 and P(Girl| Test Girl) = 1. That is, somehow, "perfection" switched from Boy to Girl. The test is perfect in "confirming" that a Boy is a Boy and has a 50% error rate in confirming that a Girl is a Girl. The test is perfect in "predicting" that a person who tests as a girl is in fact a girl but has 33% error rate in predicting that a person who tests as a Boy is in fact a Boy. Thus, the term perfect is ambiguous. Perfection in confirmation, i.e., the test conditional on the gender, does not mean perfection in prediction, i.e., the gender conditional on the test.<br />
<br />
Some of the puzzlement disappears if we deal with counts; the table below is equivalent to Gigerenzer's "tree" diagram. Assume 50 Boys and 50 Girls to start with. Every one of the 50 Boys will test as a Boy--none of the Boys test as a Girl; of the 50 Girls, 25 will test as a Boy and 25 will test as a girl. Therefore, P(Girl| Test Girl) = 1. One is tempted to to explain the switch by using the lingo of medical testing: false positives, false negatives, sensitivity, specificity, positive predictive value, negative predictive value. However, one hesitates to designate either gender as diseased even though the mathematics is the same.<br />
<center><table width="75%" border="1"><br />
<tr><br />
<th>&nbsp;</th><br />
<th>Test Boy</th><br />
<th>Test Girl</th><br />
<th>Total</th><br />
</tr><br />
<tr><br />
<th>Boy</th><br />
<th>50</th><br />
<th>0</th><br />
<th>50</th><br />
</tr><br />
<tr><br />
<th>Girl</th><br />
<th>25</th><br />
<th>25</th><br />
<th>50</th><br />
</tr><br />
</table></center><br />
<br />
Gigerenzer rightly concludes that the language of statistics is not natural for most individuals. Perhaps the puzzlement in this specific example is at least partly due to the natural language known as English. Boys, Girls, Test Boys and Test Girls are too confusing. . Replace "Boy" by "Norwegian" and "Girl" by "German" and assume that there are as many Norwegians as Germans. Let every Norwegian be "Blond," so that P(Blond| Norwegian) = 1 and only half the Germans are Blond. Thus, P(German| Not Blond) =1; the switch, P(German| Not Blond) = P(Blond| Norwegian) = 1, is rather obvious. Is the this situation easier to understand because of the linguistics--hair color and ethnicity are easily distinct as Test Boy and Boy are not?<br />
<br />
===DISCUSSION QUESTIONS===<br />
<br />
1. Gigerenzer has a chapter entitled, "(Un)Informed Consent." Based on your experience, what do you imagine the chapter contains?<br />
<br />
2. A drawing of two tables (that is, physical tables on which things are placed) appears on page 10. He claims the tables (due to Roger Shepard) are identical in size and shape. After staring at them in disbelief of the claim, how would you verify the contention?<br />
<br />
3. Physicians sometime make the following type of statement:"Never mind the statistics, I treat every patient as an individual." Defend this assertion. Criticize this assertion.<br />
<br />
4. The physicist, Lord Rutherford, is reputed to have said, " If your experiment, needs statistics you ought to have done a better experiment." Defend and criticize Lord Rutherford.<br />
<br />
5. Assume an asymptomatic woman has a mammogram which looks suspicious and then a biopsy which is negative. Would she be grateful for the clean bill of health or would she become an advocate who opposes (mass) screening? Suppose instead we assume a man has a suspiciously high PSA and the painful multiple biopsies (6-12 "sticks") are all negative. Would he be grateful for the clean bill of health or would he become an advocate who opposes (mass) screening? <br />
<br />
6. Calculated Risks also deals with the risk to the physician making a recommendation and a diagnosis. Discuss why in our present-day litigious society the risks to the physician (who may or may not recommend a test or may or may not make a diagnosis) are not symmetrical. Along these lines, who are the vested interests involved in maintaining screening and testing?<br />
<br />
7. Revisit the Boy/Girl scenario but now the test always says Boy regardless of gender, P(Test Boy| Boy) = P(Test Boy| Girl) = 1. Complete the table for this version. Obviously, this test has the advantage of being extremely simple, cost-free and non-invasive. Use either the Probability Format or the Frequency Format to comment on the statistical worthiness of this test.<br />
<br />
Submitted by Paul Alper<br />
<br />
==More medical studies that conflict with previous studies==<br />
<br />
[http://www.nytimes.com/2006/02/08/health/08fat.html?_r=1&oref=slogin Low-fat diet does not cut health risks, Study finds]<br><br />
''New York Times'', Feb. 8, 2006<br><br />
Gina Kolata<br />
<br />
[http://www.usatoday.com/news/health/2006-02-07-diet-fat-women_x.htm Cutting fat alone isn't enough, women advised]<br><br />
''USA TODAY'', Feb, 7, 2006<br><br />
Rita Rubin<br />
<br />
[http://www.post-gazette.com/pg/06040/652708.stm Popular herb shows no benefit for prostate]<br><br />
Wall street journal, Feb. 9, 2006<br><br />
Syllvia Pagan Westphal<br />
<br />
In the ''New York Times'' article we read:<br />
<br />
<blockquote>The largest study ever to ask whether a low-fat diet reduces the risk of getting cancer or heart disease has found that the diet has no effect.<br><br><br />
<br />
The $415 million federal study involved nearly 49,000 women ages 50 to 79 who were followed for eight years. In the end, those assigned to a low-fat diet had the same rates of breast cancer, colon cancer, heart attacks and strokes as those who ate whatever they pleased, researchers are reporting today.</blockquote><br />
<br />
In the ''Wall Street Journal'' article we read:<br />
<br />
<blockquote>Saw palmetto, an herbal supplement taken by 2.5 million Americans for problems with enlargement of the prostate gland, is no more effective than a placebo in alleviating the condition, according to a new study<br><br><br />
<br />
The perception that saw palmetto works had been supported by a number of clinical trials over the years. A comprehensive 2002 analysis of 21 trials involving over 3,000 men found that studies credited saw palmetto with providing "mild to moderate improvement in symptoms with fewer adverse events than finasteride (approved by the Food and Drug Administration to treat benign enlargement).</blockquote><br />
<br />
The saw palmetto study was reported in the ''New England Journal of Medicine'' February 9, 2006 and the low-fat diet study was reported in ''Jama'', February 8, 2006.<br />
<br />
The saw palmetto study had 225 participants randomized to give 112 saw palmetto and 113 placebo and the study lasted from July 2001 to May 2003.<br />
<br />
So once more the general public will wonder what the truth is. Commenting on the diet study Berkeley statistician David Freedmn is quoted as saying that the studies were well designed and should be taken seriously.<br />
<br />
Two of the 32 authors of the study, Judith Hsia, professor of medicine at George Washington University in Washington, D.C. and Ross Prentice, professor of biostatistics at the University of Washington in Seattle, were interviewed by Ira Flato on NPR's Talk of the Nation Friday Science program February 10, 2006. You can listen to them trying to do damage control [http://www.npr.org/templates/story/story.php?storyId=5200525 here] . The say that women should certainly not quit trying to control their diet. They point out that the study did not distinquish between "good" and "bad" fats. Prentice remarks that the incidence rate of breast cancer was 9% less in control group than in the placebo group. When Ira remarks that the study said that the difference was not significant, Prentice replied that you have to understand what statistical signficance meant and adds that if it were 10% it would have been signficant. <br />
<br />
The authors of the paper also comment that the study was not able to continue for the length of time originally planned and since the trend for the incidence of Breast cancer was in the right direction so it is possible that the difference might be significant over the longer time. Here is a graphic from the ''Jama'' article that shows the difference in the incident rates over time http://www.dartmouth.edu/~chance/chance_news/for_chance_news/wiki/diet.png.<br />
<br />
On Feb. 14 Kolata wrote in the ''Times'' a sequal [http://www.nytimes.com/2006/02/14/health/14fat.html Maybe you're not what you eat] to her Feb 8 article where she attempts to explain the conflicting views of the results of the Women's study. You will find [http://www.nytimes.com/2006/02/16/science/17askscience.html here] her answers to readers questions relating to her Feb. 14 article.<br />
<br />
Then in the Times on Feb. 16 she wrote an article [http://www.nytimes.com/2006/02/16/health/16bones.htm Big study finds no clear benefit of calcium pills] about another study based on the Women's study. She writes:<br />
<br />
<blockquote>The $18 million study was part of the Women's Health Initiative, a large federal project whose results have confounded some popular beliefs and raised questions about public health messages that had been addressed to the entire population.<br><br><br />
<br />
In the new study, the participants were randomly assigned to take 1,000 milligrams of calcium and 400 international units of vitamin D a day, or to take placebos, and were followed for seven years. Researchers looked for effects on bone density, fractures and colorectal cancer. The lack of an effect on colorectal cancer over the seven years was so clear that it has aroused little debate. But the effect on bones is another story.<br><br><br />
<br />
Osteoporosis specialists said the study, published today in the New England Journal of Medicine, was likely to put a dent in what has become a widespread medical practice of recommending that all women take calcium and vitamin D supplements starting at menopause if not sooner, as a sort of insurance policy against osteoporosis. But beyond that there is no agreement on what, if anything, healthy women should do.</blockquote><br />
<br />
This led to still another ''New York Times'' article by Denise Grady Feb. 19, 2006 <br />
[http://www.nytimes.com/2006/02/19/health/19health.html?ex=1140584400&en=9daef52512f69cfc&ei=507 Women's health sudies leaves questions in place of certainty] This article begins with:<br />
<br />
<blockquote>So what do women do now? The results of two major studies over the past two weeks have questioned the value of two widely recommended measures: calcium pills and vitamin D to prevent broken bones, and low-fat diets to ward off heart disease and breast and colon cancer.</blockquote><br />
<br />
The article discusses the conflicts between statisticians who are willing to accept the outcomes of the study and researchers who want to look at subgroups to try to argue that despite the lack of significance one can see hopeful signs. Statistician Susan Ellenberg remarks:<br />
<br />
The probability that you will see a spuriously positive effect gets very big very quickly.<br />
<br />
Ellenberg quotes another statistician, Richard Peto of Oxford University, who said of subgroups:<br />
<br />
<blockquote>You should always do them but you should never believe them.</blockquote><br />
<br />
You will also find in this article a nice graphic summerizing the results of the Women's study relating to low-fact diets and vitamin D.<br />
<br />
===Further reading===<br />
The low-fat diet study has attracted a lot of attention from bloggers.<br />
* [http://blog.proteinpower.com/drmike/archives/2006/02/man_bites_dog.html Man Bites Dog] and [http://blog.proteinpower.com/drmike/archives/2006/02/man_bites_dog_i.html Man Bites Dog II], Michael R. Eades, M.D. offers a critical review of the design of the study.<br />
* [http://www.weightoftheevidence.com/ Regina Wilshire's blog] on why we don't need more time and/or more studies to 'prove' that low-fat dieting really works.<br />
* [http://www.stat.columbia.edu/~cook/movabletype/archives/2006/02/do_lowfat_diets_1.html Do low-fat diets have "significant' benefits?] in Andrew Gelman's blog discusses the rejection levels and how a slight change in the data (or the rejection level) would have converted an "insignificant" result into a "significant" one in this particular case.<br />
<br />
==A day in the life of a human rights statistician==<br />
[http://www.wired.com/news/technology/1,70196-0.html Coders Bare Invasion Death Count], By Ann Harrison, Wired News, 9-Feb-06.<br><br />
[http://www.boingboing.net/2006/02/11/how_statistics_caugh.html How statistics caught Indonesia's war-criminals ], Cory Doctorow, BoingBoing.net<br />
<br />
A group of determined programmers and statisticians,<br />
the [http://www.hrdag.org/about/ Human Rights Data Analysis Group], released a [http://www.hrdag.org/resources/timor_chapter_graphs/timor_chapter_page_01.shtml report] documenting over civilian deaths in the former Portuguese colony, which occurred from a year prior to the Indonesian army's invasion in 1975, to the country's 1999 independence referendum that formally ended the occupation.<br />
[http://www.hrdag.org/about/timor-leste.shtml Statistical analysis] establishes that at least 102,800 (+/- 11,000) Timorese died as a result of the conflict. Approximately 18,600 (+/- 1000) Timorese were killed or disappeared, while the remainder died due to hunger and illness in excess of what would be expected due to peacetime mortality. <br />
<br />
Group director Patrick Ball says <br />
<blockquote><br />
By having an accurate statistical picture of the suffering, we can draw conclusions about what the causes of the violence might have been and identify likely perpetrators with a claim based on thousands of witnesses.<br />
</blockquote><br />
<br />
The group established three datasets that integrated quantitative methods into broader truth seeking activities. These datasets included:<br />
* The commission's statement-taking process, which collected almost 8,000 narrative testimonies from people in every sub-district; <br />
* A census of all public graveyards in the country (encompassing approximately 319,000 gravestones); <br />
* A retrospective mortality survey drawing on a probability sample of approximately 1,400 households throughout the thirteen districts of Timor-Leste. <br />
In establishing these data, HRDAG and the Commission for Reception, Truth and Reconciliation in East Timor (CAVR) pioneered a number of new techniques and methods. <br />
No other truth commission has ever undertaken a retrospective mortality survey. <br />
While gravestone information for mortality estimation has been used by historical demographers for mortality estimations, this is the first time that a human rights project has employed such methods. <br />
These projects were so large that HRDAG developed automated techniques to link multiple reports of the same death - a key component of [http://www.hrdag.org/resources/mult_systems_est.shtml multiple systems estimation],<br />
a technique that uses two separately collected but incomplete lists of a population to estimate the total population size.<br />
<br />
HRDAG uses the multiple systems estimation technique in human rights cases to project the total number of violations, including those that were never documented. This information is vital to producing a complete accurate historical record of the violations and to provide evidence at the trial of the architects of large-scale human rights abuses.<br />
In order to make statistical inferences from multiple systems estimation, it is necessary to:<br />
* Identify overlapping reports <br />
* Control for bias and variation in coverage rates <br />
* Estimate the total magnitude <br />
<br />
Ball has spent the last 15 years building systems and conducting qualitative analysis for large-scale human rights data projects around the world.<br />
HRGAD researchers used comparative analysis of the datasets to uncover patterns of deaths and build objective evidence of abuses. The team also developed an array of descriptive statistical analysis profiling the scale, pattern and structure of torture, ill-treatment, arbitrary detention and sexual violations. <br />
In order to estimate what was missing from the data, the HRDAG developed software to link multiple reports of the same death in a technique called record linkage. <br />
They then used multiple systems estimation to calculate the number of deaths that no one remembered. <br />
<br />
Romesh Silva, a HRDAG field statistician who led the design and implementation of the project's data, says<br />
<blockquote><br />
The Indonesian military has persistently argued that excess mortality in Timor due to its occupation of Timor was zero.<br />
This claim can now be tested empirically and transparently with the tools of science instead of merely being debated with the tools of political rhetoric.<br />
</blockquote><br />
<br />
The final report of the CAVR was handed over to the President of Timor-Leste on 31 October 2005. The President of Timor-Leste then tabled the report at a special sitting of Timor-Leste's National Parliament on 28 November, 2005 - which coincided with the 30th anniversary celebrations of Timor's Proclamation of Independence. <br />
<br />
===Further reading===<br />
* [http://www.hrdag.org/about/ The Human Rights Data Analysis Group (HRDAG)] develops information technology solutions and statistical techniques to help human rights advocates build evidence-based arguments.] See the [http://www.hrdag.org/about/faqs.shtml FAQ] for more info.<br />
* [http://www.hrdag.org/resources/timor_chapter_graphs/timor_chapter_page_01.shtml The Profile of Human Rights Violations in Timor-Leste, 1974-1999.] A Report by the Benetech Human Rights Data Analysis Group to the Commission on Reception, Truth and Reconciliation of Timor-Leste. 9 February 2006.<br />
* [http://www.hrdag.org/about/romesh_silva.shtml Romesh Silva] and [http://www.hrdag.org/about/patrick_ball.shtml Patrick Ball] designed and conducted the statistical analysis and wrote this report. Their on-line profiles provide more information about their statistical work and the awards that they have received. The are also profiles of other [http://www.hrdag.org/about/people.shtml statistical consultants] at HRDAG.<br />
Two short papers by Romesh and Ball are worth reading:<br />
* [http://paa2006.princeton.edu/download.aspx?submissionId=60827 The Demography of Large-Scale Human Rights Atrocities: Integrating demographic and statistical analysis into post-conflict historical clarification in Timor-Leste.] Romesh Silva and Patrick Ball. A 5-page paper presented at the 2006 meetings of the Population Association of America.<br />
* [http://www.austms.org.au/Publ/Gazette/2005/May05/careersilva.pdf My brilliant career - Quantitative Data Analysis and Large-Scale Human Rights Violations: An Example of Applied Statistics at the Grassroots.] Romesh Silva. Gazette of the Australian Mathematical Society. Canberra (Australia). Volume 32, Number 2, May 2005. A 5-page paper on where a mathematics education can lead you. <br />
** "in the late 1990’s as I was completing my honors degree in statistics at UNSW, I became increasingly involved with Amnesty International ... I began to wonder how I might be able to directly apply my mathematical education and quantitative skills to international human rights. ... As the field of human rights statistics is relatively new, our main challenge remains in attracting more mathematicians and statisticians to work in this area and also communicating to the human rights field how quantitative data analysis can contribute to accountability and truthtelling processes."<br />
<br />
Submitted by John Gavin.<br />
<br />
==Another record jackpot for the Powerball lottery==<br />
[http://www.startribune.com/535/story/247617.html Elusiveness of Powerball is revealed in the math]<br><br />
Minneapolis Star Tribune, Feb. 15, 2006<br><br />
Mike Meyers<br />
<br />
[http://www.latimes.com/news/opinion/commentary/la-oe-daum25feb25,0,1184552.column?coll=la-news-comment-opinions Who's the idiot now?]<br><br />
''Los Angeles Times'', Feb. 25, 2006<br><br />
Meghan Doum.<br />
<br />
When a Powerball jackpot nears a new record the media asks experts to comment on what the odds are and to explain how unlikely you are to win a lottery. See [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_8#A_record_Powerball_lottery_jackpot Chance News 8] for interesting comments of two Minnesota mathematicians related to the October 22, 2005 record $340 million Powerball jackpot. For his article related to the current record $365 jackpot, Meyers consulted [http://www.math.temple.edu/~paulos/ John Paulos] author of the bestselling book, "Innumeracy" and a monthly column [http://abcnews.go.com/Technology/WhosCounting/story?id=1560771 Who's Counting] for ABCNews.com. <br />
<br />
We read:<br />
<br />
<blockquote> Paulos says lotteries have always owed their appeal to people's loose grip of math and recalled a line from Voltaire: "Lotteries are a tax on stupidity."<br><br><br />
<br />
Paulos once tore up a Powerball ticket on the eve of a drawing in front of an audience. "They all gasped as if I just slashed the Mona Lisa," he said. </blockquote><br />
<br />
While the Voltaire quote is on many websites and usually attributed to Voltaire our librarians were unable to find its source. Perhaps a reader can provide this. However in our search we did find a similar quotation:<br />
<br />
<center>A lottery is a taxation, Upon all the fools in Creation;<br><br />
And Heav'n be prais'd, It is easily rais'd, <br><br />
Credulity's always in fashion; <br><br />
For, folly's a fund, Will never lose ground,<br><br />
While fools are so rife in the Nation.</center><br />
<div align="right">Henry Fiellding 1707-54<br><br />
</div><br />
<br />
From Wikipedia we read:<br />
<br />
<blockquote>'''Henry Fielding''' was an English novelist and dramatist known for his rich earthy humor and satirical prowess and as the author of the novel ''Tom Jones''.</blockquote><br />
<br />
The quotation comes from Fielding's play [http://www.ebookmall.com/ebook/169052-ebook.htm ''The Lottery, a farce''] (1724)<br />
<br />
In her ''Los Angeles Times'' article [http://www.latimes.com/news/opinion/commentary/la-oe-daum25feb25,0,1184552.column?coll=la-news-comment-opinions Who's the idiot now?] about the winners of the current record lottery columnist Meghan Daum writes:<br />
<blockquote>On Wednesday morning in Lincoln, Neb., after four days of speculation about who had won the biggest jackpot in Powerball history, eight employees of a ConAgra ham processing plant came forward and identified themselves as the winners of the $365-million purse. As lottery stories go, this is about as heartwarming as it gets. Two of the winners are immigrants from Vietnam and one is a political refugee from the Republic of Congo -- and all worked the second and third shifts, some clocking as many as 70 hours a week. There is probably no jobsite as gruesome as a meatpacking house. If anyone deserves an express ticket to a new life, it's these folks. </blockquote><br />
<br />
Equally moving is the [http://www.cnn.com/2006/US/02/22/powerball.winner.ap/ interview] of the winners on CNN. Click on "Watch presentation of big checks" in the article). (You have to watch a short advertisement first).<br />
<br />
==Europe's statisticians are too gloomy==<br />
[http://www.economist.com/finance/displayStory.cfm?story_id=5531335 A numbers racket], The Economist, 18-Feb-06.<br><br />
[http://www.economist.com/displaystory.cfm?story_id=E1_VVDQTDP How to measure economies], The Economist, 9-Feb-2006 (subscription required).<br />
<br />
The first article highlights how statistical biases can influence perceptions of economic growth.<br />
The second gives more information about the merits of [http://en.wikipedia.org/wiki/Gross_domestic_product gross domestic product (GDP)] relative to other economic indicators.<br />
<br />
GDP per head is the most commonly used measure of a country's success. <br />
It was primarily developed as a planning tool to measure productivity during World War II<br />
as it measures value of goods and services produced by the residents of a country.<br />
A nation's well-being depends on factors not covered by GDP, such as leisure time, income inequality and the quality of the envirnoment but GDP was never intended to measure welfare.<br />
For most purposes, it the best available indicator on a timely basis so governments worry about how to boost their GDP growth.<br />
<br />
There is a wide gap between America's and Europe's GPD per head.<br />
Since the start of [http://en.wikipedia.org/wiki/European_Monetary_Union European Monetary Union] in 1999, revisions to [http://en.wikipedia.org/wiki/Gross_domestic_product gross domestic product (GDP)] growth have almost always been upwards. In contrast, revisions in America have tended to be downwards. The initial figures which grab newspaper headlines therefore exaggerate Europe's economic underperformance. <br />
<br />
The Economist resists the obvious conclusion:<br />
<blockquote><br />
Discounting the obvious explanation that American statisticians are born optimists, it is unclear what lies behind the consistent direction of these revisions. <br />
</blockquote><br />
<br />
This article is based on a paper by Kevin Daly, an economist at Goldman Sachs.<br />
He calculates that, based on the GDP-growth figures first published in each quarter, the euro area would have grown by an annual average of only 1.6% in the six years to 2004. Yet the latest figures put the growth rate at 2.0%. <br />
In contrast, the first published figures gave America an average growth rate of 3.1%; but that has now been shaved down to 2.8%. The revisions have cut the reported gap between growth rates in America and the euro area in half. As a result, the euro area's GDP per head has in fact grown at the same pace as America's. <br />
<br />
The Economist goes on to comment:<br />
<blockquote><br />
Europe could rejoice in further upward revisions to growth if its governments were to adopt American statistical practices. Price deflators there take more account of improvements in the quality of goods, such as computers, and thus a given rise in nominal spending implies faster growth in real terms. By using higher inflation rates, the euro area understates its growth relative to America's. In addition, American statisticians consider firms' spending on software that is written in-house to be investment, while in the euro area it is often counted as an expense and so is excluded from final output. The surge in software spending has therefore inflated America's relative growth. <br />
<br><br />
<br><br />
On past experience, Europe's statisticians should add half a percentage point to their first guesses of GDP growth. By also switching to American practices, they could boost growth even further. Instead, their cautious ways are making Europe's economies look more dismal than they are, and gloomy headlines are discouraging consumers from spending. Perhaps Europe should outsource the compilation of its statistics to America, and then watch the boom.<br />
</blockquote><br />
<br />
The second Economist article says that the OECD is encouraging governments to move from relying <br />
on just one indicator. Alternatives, like [http://en.wikipedia.org/wiki/Gross_national_income gross] or net national income suggest that the gap between American and European growth rates may much smaller.<br />
<br />
===Further reading===<br />
[http://www.sbe.co.uk/pdfs/articles/34_3_Daly.pdf Has Euroland Performed That Badly?], Kevin Daly, Golman Sachs. Daly says <br />
<blockquote><br />
Euroland productivity when measured appropriately is not only close to US levels but, over the past ten years as a whole, its growth has continued to surpass that of the US. The<br />
US’s superior GDP performance over this period has not been attributable to faster productivity growth but to a more rapidly expanding labour force that is prepared to work longer hours.<br />
</blockquote><br />
<br />
Submitted by John Gavin.<br />
<br />
==Single and not so carefree==<br />
<br />
Premature mortality among lone fathers and childless men. Ringback Weitoft G, Burstrom B, Rosen M. Soc Sci Med. 2004 Oct;59(7):1449-59.<br />
<br />
This study is a couple of years old, but it is interesting in itself and in how it was reported by a conservative advocacy group. I have not read the full article, so I can only comment on the abstract, which is [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15246173&dopt=Citation available on PubMed].<br />
<br />
These researchers studied 682,919 men and divided them into five groups (lone fathers with custody of their child/children, lone fathers without custody, childless men with a wife, childless men without a wife, and men with a wife and men with a wife and child/children. The last group was the comparison group for all comparisons. They analyzed deaths in these groups from 1991 to 2000.<br />
<br />
<blockquote>"The results suggest that lone non-custodial fathers and lone childless men face the greatest increase in risks, especially from injury and addiction, and also from all-cause mortality and ischaemic heart disease. Being a lone custodial father also entails increased risk, although generally to a much lesser extent, and not for all outcomes. The elevated risks found in all the subgroups considered diminished substantially when proxy variables to control for health-selection effects and socioeconomic circumstances were added to the initial model. Risks fell most in response to introduction of the socioeconomic variables, but health selection also played a major role, mostly in the cases of lone non-custodial fathers and lone childless men. However, even following these adjustments, significant risk increases, although greatly attenuated, remained for all the subgroups."</blockquote><br />
<br />
No mention was made about adjustment for age, but this would have to be done because there is almost certainly a large disparity in the age of men with and without children.<br />
<br />
I became aware of this paper when my brother-in-law sent me an email describing the study that was produced by [http://www.profam.org/Default.htm The Howard Center for Family, Religion, & Society]. This group is located in Rockford, Illinois and does not seem to be associated with Howard University. This group advocates for many conservative family values causes, and opposes gay marriage and no fault divorce. They regularly summarize research studies that support their political viewpoint. There are many other organizations, of course, that advocate viewpoints of all types and they also summarize studies that favor their political outlook.<br />
<br />
There was a large discrepancy, however, in the information provided in the abstract and the information provided by this website. In particular, the website lists actual numbers from the publication itself while the abstract did not report any quantitative results.<br />
<br />
<blockquote>Sharp differences in mortality rates separated these five groups, with men living alone, apart from their children, at greatest risk of premature death. In comparison with men living with a wife (or partner) and their children, fathers living alone—without spouse (or partner) and apart from their children—experienced “almost 4 times as great a risk of all-cause mortality, 10 times of death from external violence, 13 times from fall and poisoning, almost 5 times from suicide, and 19 times from addiction.”</blockquote><br />
<br />
You can read [http://www.profam.org/pub/nr/nr_1811.htm#Men_Dying_Alone the full summary] which does mention the attenuation of these effects after statistical adjustments, but does not report the adjusted rates, only the unadjusted ratios.<br />
<br />
===Questions===<br />
<br />
1. What do you think the "proxy variables to control for health-selection effects and socioeconomic circumstances" are?<br />
<br />
2. Why is it important to adjust for these variables and why are proxies needed?<br />
<br />
3. List some covariates which could possibly be imbalanced between the five groups studied other than health selection effects, socioeconomic circumstances, and presumably age. Could any of these influence mortality results?<br />
<br />
4. Why would a reviewer be interested in the unadjusted ratios rather than the adjusted ratios?<br />
<br />
5. Do you feel that the Howard Center for Family, Religion, & Society summary is a fair and balanced representation of the work by Ringback Weitoft et al? Be sure to read [http://www.profam.org/pub/nr/nr_1811.htm#Men_Dying_Alone the full summary] rather than my extract, because my summary of their summary could be biased.<br />
<br />
6. Should the original authors have included more quantitative results in their abstract?<br />
<br />
Submitted by Steve Simon</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_14&diff=2238Chance News 142006-02-27T03:52:13Z<p>Thekohser: Corrected NPR audio link (from LA Times)</p>
<hr />
<div>==Quotation== <br />
<blockquote>The [Supreme] Court concluded that mental health professionals' predictions were "not always wrong...only most of the time."</blockquote><br />
<div align="right">Gerd Gigerenzer <br><br />
</div><br />
<br />
==Forsooth==<br />
<br />
<br />
<br />
<blockquote> In theory, if you were to buy 50 tickets and your neighbor bought one, neither of you would have a better or worse chance of winning, We like to say it only takes one ticket to win."<br />
</blockquote><br />
<br />
<div align="right">Brian Rockey, a spokesman for the Nebraska Lottery<br><br />
in a discussion of the record Powerball jackpot of 360 million dollars.<br><br />
Omaha World-Herald (Nebraska) February 18, 2007 Pg. 01A. </div><br />
<br />
==Gerd Gigerenzer's Calculated Risks Revisited==<br />
[http://www.dartmouth.edu/%7Echance/chance_news/recent_news/chance_news_11.03.html#item10 Chance News 11.03] had a lengthy and very positive review of Gerd Gigerenzer's book '''Calculated Risks: How To Know When Numbers Deceive You'''.<br />
Readers are urged to download that excellent review because of the information contained. However, the book is so good and so persuasive that it is worth another look in order to alert readers to some other aspects of the book and how it relates to subsequent events.<br />
<br />
The aforementioned review did not mention the abundant number of actual, real-world incidents cited in which doctors, lawyers and social workers, not to mention patients, clients and jurors, were unable to unscramble the difference between P(X| Y) and P(Y| X). Also not mentioned was Gigerenzer's dim view of screening for breast cancer and prostate cancer. Screening may be defined, according to H. Gilbert Welch, as "the systematic examination of asymptomatic people to detect and treat disease." See [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_12#Screening Chance News 12] for a review of Welch's 2004 book '''Should I Be Tested For Cancer? Maybe Not And Here's Why'''. Welch echoes and amplifies Gigerenzer contention that (mass) screening is counterproductive, especially when there is little evidence that a cure exists. Just to complicate matters, however, see [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_8#Mammograms_Validated_as_Key_in_Cancer_Fight "Mammograms validated as key in cancer fight"] in Chance News 8 which indicates that mammography screening does reduce the death rate of breast cancer, . Unfortunately, the article in the ''New England Journal of Medicine'' referred to does not explain why mammogram screening is deemed responsible for 28 to 65% of the 24% drop in the breast cancer death rate.<br />
Gigerenzer would prefer, and this is one of his main points, that any statistical data be given in counts rather than in percentages, especially percentages without a base rate, such as relative risk which he views as the most misleading. <br />
<center><table width="100%" border="1"><br />
<tr><br />
<th>Treatment</th><br />
<th>Deaths per 1000 women</th> <br />
<tr><br />
<td>No mammography screening</td><br />
<th>4</th><br />
</tr><br />
<tr><br />
<td>Mammography screening</td><br />
<th>3</th><br />
</tr><br />
</table></center><br />
<br />
Consequently, there is "a 25 percent relative risk reduction." He would prefer focusing on the difference in the number of deaths which yields the more revealing and perhaps more honest statement: "The absolute risk reduction is 4 minus 3, that is, 1 out of 1000 women (which corresponds to .1 percent)." However, "Counting on their clients' innumeracy, organizations that want to impress upon clients the benefits of treatment generally report them in terms of relative risk reduction...applicants [for grants] often feel compelled to report relative risk reductions because they sound more impressive." Although he did not use this example, one's relative "risk" of winning the lottery is infinitely greater if one buys a ticket, yet one's absolute "risk" of winning has hardly improved at all.<br />
<br />
Most of his numerical examples are typified by his discussion of the cartoon given below <br />
<br />
<center>[[Image:gigerenzer1.gif|500px]]</center><br />
<br />
which indicates the superiority of dealing with counts. Note that "H" represents having the disease and "D" represents a diagnosis having the symptom as seen by testing positive. Characteristically, there is a large number in the population who do not have the disease and because of the possibility of a wrong classification, the number of false positives (99) outweighs the number of true positives (8) resulting in P(disease| symptom) being much lower (8/(8+99)) than P(symptom| disease) (.8). This type of result, low probability of disease given symptom, is true even when ".8" is replaced by a number much closer to 1 provided there are many more who do not have the disease.<br />
<br />
Here is an example he did not consider but it also illustrates the superiority of dealing with counts. Instead of two populations--diseased and healthy--which are greatly different in size, consider Boys and Girls and the desire to predict gender based on some simple test. Assume that 50% of births are Boys so that P(Boy) = P(Girl) = 1/2. A simple, inexpensive, non-invasive gender-testing procedure indicates that it is "perfect" for boys, P(Test Boy| Boy) = 1, implying P(Test Girl| Boy) = 0. Unfortunately, this simple, inexpensive, non-invasive gender-testing procedure for girls is a "coin toss," P(Test Girl| Girl) = P(Test Boy| Girl) = 1/2. Application of Bayes theorem yields what seems to be a strange inversion, P(Boy| Test Boy) = 2/3 and P(Girl| Test Girl) = 1. That is, somehow, "perfection" switched from Boy to Girl. The test is perfect in "confirming" that a Boy is a Boy and has a 50% error rate in confirming that a Girl is a Girl. The test is perfect in "predicting" that a person who tests as a girl is in fact a girl but has 33% error rate in predicting that a person who tests as a Boy is in fact a Boy. Thus, the term perfect is ambiguous. Perfection in confirmation, i.e., the test conditional on the gender, does not mean perfection in prediction, i.e., the gender conditional on the test.<br />
<br />
Some of the puzzlement disappears if we deal with counts; the table below is equivalent to Gigerenzer's "tree" diagram. Assume 50 Boys and 50 Girls to start with. Every one of the 50 Boys will test as a Boy--none of the Boys test as a Girl; of the 50 Girls, 25 will test as a Boy and 25 will test as a girl. Therefore, P(Girl| Test Girl) = 1. One is tempted to to explain the switch by using the lingo of medical testing: false positives, false negatives, sensitivity, specificity, positive predictive value, negative predictive value. However, one hesitates to designate either gender as diseased even though the mathematics is the same.<br />
<center><table width="75%" border="1"><br />
<tr><br />
<th>&nbsp;</th><br />
<th>Test Boy</th><br />
<th>Test Girl</th><br />
<th>Total</th><br />
</tr><br />
<tr><br />
<th>Boy</th><br />
<th>50</th><br />
<th>0</th><br />
<th>50</th><br />
</tr><br />
<tr><br />
<th>Girl</th><br />
<th>25</th><br />
<th>25</th><br />
<th>50</th><br />
</tr><br />
</table></center><br />
<br />
Gigerenzer rightly concludes that the language of statistics is not natural for most individuals. Perhaps the puzzlement in this specific example is at least partly due to the natural language known as English. Boys, Girls, Test Boys and Test Girls are too confusing. . Replace "Boy" by "Norwegian" and "Girl" by "German" and assume that there are as many Norwegians as Germans. Let every Norwegian be "Blond," so that P(Blond| Norwegian) = 1 and only half the Germans are Blond. Thus, P(German| Not Blond) =1; the switch, P(German| Not Blond) = P(Blond| Norwegian) = 1, is rather obvious. Is the this situation easier to understand because of the linguistics--hair color and ethnicity are easily distinct as Test Boy and Boy are not?<br />
<br />
===DISCUSSION QUESTIONS===<br />
<br />
1. Gigerenzer has a chapter entitled, "(Un)Informed Consent." Based on your experience, what do you imagine the chapter contains?<br />
<br />
2. A drawing of two tables (that is, physical tables on which things are placed) appears on page 10. He claims the tables (due to Roger Shepard) are identical in size and shape. After staring at them in disbelief of the claim, how would you verify the contention?<br />
<br />
3. Physicians sometime make the following type of statement:"Never mind the statistics, I treat every patient as an individual." Defend this assertion. Criticize this assertion.<br />
<br />
4. The physicist, Lord Rutherford, is reputed to have said, " If your experiment, needs statistics you ought to have done a better experiment." Defend and criticize Lord Rutherford.<br />
<br />
5. Assume an asymptomatic woman has a mammogram which looks suspicious and then a biopsy which is negative. Would she be grateful for the clean bill of health or would she become an advocate who opposes (mass) screening? Suppose instead we assume a man has a suspiciously high PSA and the painful multiple biopsies (6-12 "sticks") are all negative. Would he be grateful for the clean bill of health or would he become an advocate who opposes (mass) screening? <br />
<br />
6. Calculated Risks also deals with the risk to the physician making a recommendation and a diagnosis. Discuss why in our present-day litigious society the risks to the physician (who may or may not recommend a test or may or may not make a diagnosis) are not symmetrical. Along these lines, who are the vested interests involved in maintaining screening and testing?<br />
<br />
7. Revisit the Boy/Girl scenario but now the test always says Boy regardless of gender, P(Test Boy| Boy) = P(Test Boy| Girl) = 1. Complete the table for this version. Obviously, this test has the advantage of being extremely simple, cost-free and non-invasive. Use either the Probability Format or the Frequency Format to comment on the statistical worthiness of this test.<br />
<br />
Submitted by Paul Alper<br />
<br />
==More medical studies the conflict with previous studies==<br />
<br />
[http://www.nytimes.com/2006/02/08/health/08fat.html?_r=1&oref=slogin Low-fat diet does not cut health risks, Study finds]<br><br />
''New York Times'', Feb. 8, 2006<br><br />
Gina Kolata<br />
<br />
[http://www.usatoday.com/news/health/2006-02-07-diet-fat-women_x.htm Cutting fat alone isn't enough, women advised]<br><br />
''USA TODAY'', Feb, 7, 2006<br><br />
Rita Rubin<br />
<br />
[http://www.post-gazette.com/pg/06040/652708.stm Popular herb shows no benefit for prostate]<br><br />
Wall street journal, Feb. 9, 2006<br><br />
Syllvia Pagan Westphal<br />
<br />
In the ''New York Times'' article we read:<br />
<br />
<blockquote>The largest study ever to ask whether a low-fat diet reduces the risk of getting cancer or heart disease has found that the diet has no effect.<br><br><br />
<br />
The $415 million federal study involved nearly 49,000 women ages 50 to 79 who were followed for eight years. In the end, those assigned to a low-fat diet had the same rates of breast cancer, colon cancer, heart attacks and strokes as those who ate whatever they pleased, researchers are reporting today.</blockquote><br />
<br />
In the ''Wall Street Journal'' article we read:<br />
<br />
<blockquote>Saw palmetto, an herbal supplement taken by 2.5 million Americans for problems with enlargement of the prostate gland, is no more effective than a placebo in alleviating the condition, according to a new study<br><br><br />
<br />
The perception that saw palmetto works had been supported by a number of clinical trials over the years. A comprehensive 2002 analysis of 21 trials involving over 3,000 men found that studies credited saw palmetto with providing "mild to moderate improvement in symptoms with fewer adverse events than finasteride (approved by the Food and Drug Administration to treat benign enlargement).</blockquote><br />
<br />
The saw palmetto study was reported in the ''New England Journal of Medicine'' February 9, 2006 and the low-fat diet study was reported in ''Jama'', February 8, 2006.<br />
<br />
The saw palmetto study had 225 participants randomized to give 112 saw palmetto and 113 placebo and the study lasted from July 2001 to May 2003.<br />
<br />
So once more the general public will wonder what the truth is. Commenting on the diet study Berkeley statistician David Freedmn is quoted as saying that the studies were well designed and should be taken seriously.<br />
<br />
Two of the 32 authors of the study, Judith Hsia, professor of medicine at George Washington University in Washington, D.C. and Ross Prentice, professor of biostatistics at the University of Washington in Seattle, were interviewed by Ira Flato on NPR's Talk of the Nation Friday Science program February 10, 2006. You can listen to them trying to do damage control [http://www.npr.org/templates/story/story.php?storyId=5200525 here] . The say that women should certainly not quit trying to control their diet. They point out that the study did not distinquish between "good" and "bad" fats. Prentice remarks that the incidence rate of breast cancer was 9% less in control group than in the placebo group. When Ira remarks that the study said that the difference was not significant, Prentice replied that you have to understand what statistical signficance meant and adds that if it were 10% it would have been signficant. <br />
<br />
The authors of the paper also comment that the study was not able to continue for the length of time originally planned and since the trend for the incidence of Breast cancer was in the right direction so it is possible that the difference might be significant over the longer time. Here is a graphic from the ''Jama'' article that shows the difference in the incident rates over time http://www.dartmouth.edu/~chance/chance_news/for_chance_news/wiki/diet.png.<br />
<br />
On Feb. 14 Kolata wrote in the ''Times'' a sequal [http://www.nytimes.com/2006/02/14/health/14fat.html Maybe you're not what you eat] to her Feb 8 article where she attempts to explain the conflicting views of the results of the Women's study. You will find [http://www.nytimes.com/2006/02/16/science/17askscience.html here] her answers to readers questions relating to her Feb. 14 article.<br />
<br />
Then in the Times on Feb. 16 she wrote an article [http://www.nytimes.com/2006/02/16/health/16bones.htm Big study finds no clear benefit of calcium pills] about another study based on the Women's study. She writes:<br />
<br />
<blockquote>The $18 million study was part of the Women's Health Initiative, a large federal project whose results have confounded some popular beliefs and raised questions about public health messages that had been addressed to the entire population.<br><br><br />
<br />
In the new study, the participants were randomly assigned to take 1,000 milligrams of calcium and 400 international units of vitamin D a day, or to take placebos, and were followed for seven years. Researchers looked for effects on bone density, fractures and colorectal cancer. The lack of an effect on colorectal cancer over the seven years was so clear that it has aroused little debate. But the effect on bones is another story.<br><br><br />
<br />
Osteoporosis specialists said the study, published today in the New England Journal of Medicine, was likely to put a dent in what has become a widespread medical practice of recommending that all women take calcium and vitamin D supplements starting at menopause if not sooner, as a sort of insurance policy against osteoporosis. But beyond that there is no agreement on what, if anything, healthy women should do.</blockquote><br />
<br />
This led to still another ''New York Times'' article by Denise Grady Feb. 19, 2006 <br />
[http://www.nytimes.com/2006/02/19/health/19health.html?ex=1140584400&en=9daef52512f69cfc&ei=507 Women's health sudies leaves questions in place of certainty] This article begins with:<br />
<br />
<blockquote>So what do women do now? The results of two major studies over the past two weeks have questioned the value of two widely recommended measures: calcium pills and vitamin D to prevent broken bones, and low-fat diets to ward off heart disease and breast and colon cancer.</blockquote><br />
<br />
The article discusses the conflicts between statisticians who are willing to accept the outcomes of the study and researchers who want to look at subgroups to try to argue that despite the lack of significance one can see hopeful signs. Statistician Susan Ellenberg remarks:<br />
<br />
The probability that you will see a spuriously positive effect gets very big very quickly.<br />
<br />
Ellenberg quotes another statistician, Richard Peto of Oxford University, who said of subgroups:<br />
<br />
<blockquote>You should always do them but you should never believe them.</blockquote><br />
<br />
You will also find in this article a nice graphic summerizing the results of the Women's study relating to low-fact diets and vitamin D.<br />
<br />
===Further reading===<br />
The low-fat diet study has attracted a lot of attention from bloggers.<br />
* [http://blog.proteinpower.com/drmike/archives/2006/02/man_bites_dog.html Man Bites Dog] and [http://blog.proteinpower.com/drmike/archives/2006/02/man_bites_dog_i.html Man Bites Dog II], Michael R. Eades, M.D. offers a critical review of the design of the study.<br />
* [http://www.weightoftheevidence.com/ Regina Wilshire's blog] on why we don't need more time and/or more studies to 'prove' that low-fat dieting really works.<br />
<br />
==A day in the life of a human rights statistician==<br />
[http://www.wired.com/news/technology/1,70196-0.html Coders Bare Invasion Death Count], By Ann Harrison, Wired News, 9-Feb-06.<br><br />
[http://www.boingboing.net/2006/02/11/how_statistics_caugh.html How statistics caught Indonesia's war-criminals ], Cory Doctorow, BoingBoing.net<br />
<br />
A group of determined programmers and statisticians,<br />
the [http://www.hrdag.org/about/ Human Rights Data Analysis Group], released a [http://www.hrdag.org/resources/timor_chapter_graphs/timor_chapter_page_01.shtml report] documenting over civilian deaths in the former Portuguese colony, which occurred from a year prior to the Indonesian army's invasion in 1975, to the country's 1999 independence referendum that formally ended the occupation.<br />
[http://www.hrdag.org/about/timor-leste.shtml Statistical analysis] establishes that at least 102,800 (+/- 11,000) Timorese died as a result of the conflict. Approximately 18,600 (+/- 1000) Timorese were killed or disappeared, while the remainder died due to hunger and illness in excess of what would be expected due to peacetime mortality. <br />
<br />
Group director Patrick Ball says <br />
<blockquote><br />
By having an accurate statistical picture of the suffering, we can draw conclusions about what the causes of the violence might have been and identify likely perpetrators with a claim based on thousands of witnesses.<br />
</blockquote><br />
<br />
The group established three datasets that integrated quantitative methods into broader truth seeking activities. These datasets included:<br />
* The commission's statement-taking process, which collected almost 8,000 narrative testimonies from people in every sub-district; <br />
* A census of all public graveyards in the country (encompassing approximately 319,000 gravestones); <br />
* A retrospective mortality survey drawing on a probability sample of approximately 1,400 households throughout the thirteen districts of Timor-Leste. <br />
In establishing these data, HRDAG and the Commission for Reception, Truth and Reconciliation in East Timor (CAVR) pioneered a number of new techniques and methods. <br />
No other truth commission has ever undertaken a retrospective mortality survey. <br />
While gravestone information for mortality estimation has been used by historical demographers for mortality estimations, this is the first time that a human rights project has employed such methods. <br />
These projects were so large that HRDAG developed automated techniques to link multiple reports of the same death - a key component of [http://www.hrdag.org/resources/mult_systems_est.shtml multiple systems estimation],<br />
a technique that uses two separately collected but incomplete lists of a population to estimate the total population size.<br />
<br />
HRDAG uses the multiple systems estimation technique in human rights cases to project the total number of violations, including those that were never documented. This information is vital to producing a complete accurate historical record of the violations and to provide evidence at the trial of the architects of large-scale human rights abuses.<br />
In order to make statistical inferences from multiple systems estimation, it is necessary to:<br />
* Identify overlapping reports <br />
* Control for bias and variation in coverage rates <br />
* Estimate the total magnitude <br />
<br />
Ball has spent the last 15 years building systems and conducting qualitative analysis for large-scale human rights data projects around the world.<br />
HRGAD researchers used comparative analysis of the datasets to uncover patterns of deaths and build objective evidence of abuses. The team also developed an array of descriptive statistical analysis profiling the scale, pattern and structure of torture, ill-treatment, arbitrary detention and sexual violations. <br />
In order to estimate what was missing from the data, the HRDAG developed software to link multiple reports of the same death in a technique called record linkage. <br />
They then used multiple systems estimation to calculate the number of deaths that no one remembered. <br />
<br />
Romesh Silva, a HRDAG field statistician who led the design and implementation of the project's data, says<br />
<blockquote><br />
The Indonesian military has persistently argued that excess mortality in Timor due to its occupation of Timor was zero.<br />
This claim can now be tested empirically and transparently with the tools of science instead of merely being debated with the tools of political rhetoric.<br />
</blockquote><br />
<br />
The final report of the CAVR was handed over to the President of Timor-Leste on 31 October 2005. The President of Timor-Leste then tabled the report at a special sitting of Timor-Leste's National Parliament on 28 November, 2005 - which coincided with the 30th anniversary celebrations of Timor's Proclamation of Independence. <br />
<br />
===Further reading===<br />
* [http://www.hrdag.org/about/ The Human Rights Data Analysis Group (HRDAG)] develops information technology solutions and statistical techniques to help human rights advocates build evidence-based arguments.] See the [http://www.hrdag.org/about/faqs.shtml FAQ] for more info.<br />
* [http://www.hrdag.org/resources/timor_chapter_graphs/timor_chapter_page_01.shtml The Profile of Human Rights Violations in Timor-Leste, 1974-1999.] A Report by the Benetech Human Rights Data Analysis Group to the Commission on Reception, Truth and Reconciliation of Timor-Leste. 9 February 2006.<br />
* [http://www.hrdag.org/about/romesh_silva.shtml Romesh Silva] and [http://www.hrdag.org/about/patrick_ball.shtml Patrick Ball] designed and conducted the statistical analysis and wrote this report. Their on-line profiles provide more information about their statistical work and the awards that they have received. The are also profiles of other [http://www.hrdag.org/about/people.shtml statistical consultants] at HRDAG.<br />
Two short papers by Romesh and Ball are worth reading:<br />
* [http://paa2006.princeton.edu/download.aspx?submissionId=60827 The Demography of Large-Scale Human Rights Atrocities: Integrating demographic and statistical analysis into post-conflict historical clarification in Timor-Leste.] Romesh Silva and Patrick Ball. A 5-page paper presented at the 2006 meetings of the Population Association of America.<br />
* [http://www.austms.org.au/Publ/Gazette/2005/May05/careersilva.pdf My brilliant career - Quantitative Data Analysis and Large-Scale Human Rights Violations: An Example of Applied Statistics at the Grassroots.] Romesh Silva. Gazette of the Australian Mathematical Society. Canberra (Australia). Volume 32, Number 2, May 2005. A 5-page paper on where a mathematics education can lead you. <br />
** "in the late 1990’s as I was completing my honors degree in statistics at UNSW, I became increasingly involved with Amnesty International ... I began to wonder how I might be able to directly apply my mathematical education and quantitative skills to international human rights. ... As the field of human rights statistics is relatively new, our main challenge remains in attracting more mathematicians and statisticians to work in this area and also communicating to the human rights field how quantitative data analysis can contribute to accountability and truthtelling processes."<br />
<br />
Submitted by John Gavin.<br />
<br />
==Another record jackpot for the Powerball lottery==<br />
[http://www.startribune.com/535/story/247617.html Elusiveness of Powerball is revealed in the math]<br><br />
Minneapolis Star Tribune, Feb. 15, 2006<br><br />
Mike Meyers<br />
<br />
[http://www.latimes.com/news/columnists/la-oe-daum25feb25,1,5399378.column?coll=la-news-columns&ctrack=1&cset=true Who's the idiot now?]<br><br />
''Los Angeles Times'', Feb. 25, 2006<br><br />
Meghan Doum.<br />
<br />
When a powerball jackpot nears a new record the media asks experts to comment on what the odds are and to explain how unlikely you are to win a lottery. See [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_8#A_record_powerball_lottery_jackpot Chance News 8] for interesting comments of two Minnesota mathematicians related to the October 22, 2005 record $340 million powerball jackpot. For his article related to the current record $365 jackpot, Meyers consulted [http://www.math.temple.edu/~paulos/ John Paulos] author of the bestselling book, "Innumeracy" and a monthly column [http://abcnews.go.com/Technology/WhosCounting/story?id=1560771 Who's Counting] for ABCNews.com. <br />
<br />
We read:<br />
<br />
<blockquote> Paulos says lotteries have always owed their appeal to people's loose grip of math and recalled a line from Voltaire: "Lotteries are a tax on stupidity."<br><br><br />
<br />
Paulos once tore up a Powerball ticket on the eve of a drawing in front of an audience. "They all gasped as if I just slashed the Mona Lisa," he said. </blockquote><br />
<br />
While the Voltaire quote is on many websites and usually attributed to Voltaire our librarians were unable to find its source. Perhaps a reader can provide this. However in our search we did find a similar quotation:<br />
<br />
<center>A lottery is a taxation, Upon all the fools in Creation;<br><br />
And Heav'n be prais'd, It is easily rais'd, <br><br />
Credulity's always in fashion; <br><br />
For, folly's a fund, Will never lose ground,<br><br />
While fools are so rife in the Nation.</center><br />
<div align="right">Henry Fiellding 1707-54<br><br />
</div><br />
<br />
From Wikipedia we read:<br />
<br />
<blockquote>'''Henry Fielding''' was an English novelist and dramatist known for his rich earthy humor and satirical prowess and as the author of the novel ''Tom Jones''.</blockquote><br />
<br />
The quotation comes from Fielding's play [http://www.ebookmall.com/ebook/169052-ebook.htm ''The Lottery, a farce''] (1724)<br />
<br />
In her ''Los Angeles Times'' article [http://www.latimes.com/news/columnists/la-oe-daum25feb25,1,5399378.column?coll=la-news-columns&ctrack=1&cset=true"Who's the idiot now?] about the winners of the current record lottery columnest Meghan Daum writes:<br />
<blockquote>On Wednesday morning in Lincoln, Neb., after four days of speculation about who had won the biggest jackpot in Powerball history, eight employees of a ConAgra ham processing plant came forward and identified themselves as the winners of the $365-million purse. As lottery stories go, this is about as heartwarming as it gets. Two of the winners are immigrants from Vietnam and one is a political refugee from the Republic of Congo -- and all worked the second and third shifts, some clocking as many as 70 hours a week. There is probably no jobsite as gruesome as a meatpacking house. If anyone deserves an express ticket to a new life, it's these folks. </blockquote><br />
<br />
Equally moving is to listen [http://www.npr.org/templates/story/story.php?storyId=5228654] to the winners answers in an interview by Sara McCammon on NPR ''All things considered'' Feb. 22, 2006.<br />
<br />
==Europe's statisticians are too gloomy==<br />
[http://www.economist.com/finance/displayStory.cfm?story_id=5531335 A numbers racket], The Economist, 18-Feb-06.<br><br />
[http://www.economist.com/displaystory.cfm?story_id=E1_VVDQTDP How to measure economies], The Economist, 9-Feb-2006 (subscription required).<br />
<br />
The first article highlights how statistical biases can influence perceptions of economic growth.<br />
The second gives more information about the merits of [http://en.wikipedia.org/wiki/Gross_domestic_product gross domestic product (GDP)] relative to other economic indicators.<br />
<br />
GDP per head is the most commonly used measure of a country's success. <br />
It was primarily developed as a planning tool to measure productivity during World War II<br />
as it measures value of goods and services produced by the residents of a country.<br />
A nation's well-being depends on factors not covered by GDP, such as leisure time, income inequality and the quality of the envirnoment but GDP was never intended to measure welfare.<br />
For most purposes, it the best available indicator on a timely basis so governments worry about how to boost their GDP growth.<br />
<br />
There is a wide gap between America's and Europe's GPD per head.<br />
Since the start of [http://en.wikipedia.org/wiki/European_Monetary_Union European Monetary Union] in 1999, revisions to [http://en.wikipedia.org/wiki/Gross_domestic_product gross domestic product (GDP)] growth have almost always been upwards. In contrast, revisions in America have tended to be downwards. The initial figures which grab newspaper headlines therefore exaggerate Europe's economic underperformance. <br />
<br />
The Economist resists the obvious conclusion:<br />
<blockquote><br />
Discounting the obvious explanation that American statisticians are born optimists, it is unclear what lies behind the consistent direction of these revisions. <br />
</blockquote><br />
<br />
This article is based on a paper by Kevin Daly, an economist at Goldman Sachs.<br />
He calculates that, based on the GDP-growth figures first published in each quarter, the euro area would have grown by an annual average of only 1.6% in the six years to 2004. Yet the latest figures put the growth rate at 2.0%. <br />
In contrast, the first published figures gave America an average growth rate of 3.1%; but that has now been shaved down to 2.8%. The revisions have cut the reported gap between growth rates in America and the euro area in half. As a result, the euro area's GDP per head has in fact grown at the same pace as America's. <br />
<br />
The Economist goes on to comment:<br />
<blockquote><br />
Europe could rejoice in further upward revisions to growth if its governments were to adopt American statistical practices. Price deflators there take more account of improvements in the quality of goods, such as computers, and thus a given rise in nominal spending implies faster growth in real terms. By using higher inflation rates, the euro area understates its growth relative to America's. In addition, American statisticians consider firms' spending on software that is written in-house to be investment, while in the euro area it is often counted as an expense and so is excluded from final output. The surge in software spending has therefore inflated America's relative growth. <br />
<br><br />
<br><br />
On past experience, Europe's statisticians should add half a percentage point to their first guesses of GDP growth. By also switching to American practices, they could boost growth even further. Instead, their cautious ways are making Europe's economies look more dismal than they are, and gloomy headlines are discouraging consumers from spending. Perhaps Europe should outsource the compilation of its statistics to America, and then watch the boom.<br />
</blockquote><br />
<br />
The second Economist article says that the OECD is encouraging governments to move from relying <br />
on just one indicator. Alternatives, like [http://en.wikipedia.org/wiki/Gross_national_income gross] or net national income suggest that the gap between American and European growth rates may much smaller.<br />
<br />
===Further reading===<br />
[http://www.sbe.co.uk/pdfs/articles/34_3_Daly.pdf Has Euroland Performed That Badly?], Kevin Daly, Golman Sachs. Daly says <br />
<blockquote><br />
Euroland productivity when measured appropriately is not only close to US levels but, over the past ten years as a whole, its growth has continued to surpass that of the US. The<br />
US’s superior GDP performance over this period has not been attributable to faster productivity growth but to a more rapidly expanding labour force that is prepared to work longer hours.<br />
</blockquote><br />
<br />
Submitted by John Gavin.<br />
<br />
==Single and not so carefree==<br />
<br />
Premature mortality among lone fathers and childless men. Ringback Weitoft G, Burstrom B, Rosen M. Soc Sci Med. 2004 Oct;59(7):1449-59.<br />
<br />
This study is a couple of years old, but it is interesting in itself and in how it was reported by a conservative advocacy group. I have not read the full article, so I can only comment on the abstract, which is [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15246173&dopt=Citation available on PubMed].<br />
<br />
These researchers studied 682,919 men and divided them into five groups (lone fathers with custody of their child/children, lone fathers without custody, childless men with a wife, childless men without a wife, and men with a wife and men with a wife and child/children. The last group was the comparison group for all comparisons. They analyzed deaths in these groups from 1991 to 2000.<br />
<br />
<blockquote>"The results suggest that lone non-custodial fathers and lone childless men face the greatest increase in risks, especially from injury and addiction, and also from all-cause mortality and ischaemic heart disease. Being a lone custodial father also entails increased risk, although generally to a much lesser extent, and not for all outcomes. The elevated risks found in all the subgroups considered diminished substantially when proxy variables to control for health-selection effects and socioeconomic circumstances were added to the initial model. Risks fell most in response to introduction of the socioeconomic variables, but health selection also played a major role, mostly in the cases of lone non-custodial fathers and lone childless men. However, even following these adjustments, significant risk increases, although greatly attenuated, remained for all the subgroups."</blockquote><br />
<br />
No mention was made about adjustment for age, but this would have to be done because there is almost certainly a large disparity in the age of men with and without children.<br />
<br />
I became aware of this paper when my brother-in-law sent me an email describing the study that was produced by [http://www.profam.org/Default.htm The Howard Center for Family, Religion, & Society]. This group is located in Rockford, Illinois and does not seem to be associated with Howard University. This group advocates for many conservative family values causes, and opposes gay marriage and no fault divorce. They regularly summarize research studies that support their political viewpoint. There are many other organizations, of course, that advocate viewpoints of all types and they also summarize studies that favor their political outlook.<br />
<br />
There was a large discrepancy, however, in the information provided in the abstract and the information provided by this website. In particular, the website lists actual numbers from the publication itself while the abstract did not report any quantitative results.<br />
<br />
<blockquote>Sharp differences in mortality rates separated these five groups, with men living alone, apart from their children, at greatest risk of premature death. In comparison with men living with a wife (or partner) and their children, fathers living alone—without spouse (or partner) and apart from their children—experienced “almost 4 times as great a risk of all-cause mortality, 10 times of death from external violence, 13 times from fall and poisoning, almost 5 times from suicide, and 19 times from addiction.”</blockquote><br />
<br />
You can read [http://www.profam.org/pub/nr/nr_1811.htm#Men_Dying_Alone the full summary] which does mention the attenuation of these effects after statistical adjustments, but does not report the adjusted rates, only the unadjusted ratios.<br />
<br />
===Questions===<br />
<br />
1. What do you think the "proxy variables to control for health-selection effects and socioeconomic circumstances" are?<br />
<br />
2. Why is it important to adjust for these variables and why are proxies needed?<br />
<br />
3. List some covariates which could possibly be imbalanced between the five groups studied other than health selection effects, socioeconomic circumstances, and presumably age. Could any of these influence mortality results?<br />
<br />
4. Why would a reviewer be interested in the unadjusted ratios rather than the adjusted ratios?<br />
<br />
5. Do you feel that the Howard Center for Family, Religion, & Society summary is a fair and balanced representation of the work by Ringback Weitoft et al? Be sure to read [http://www.profam.org/pub/nr/nr_1811.htm#Men_Dying_Alone the full summary] rather than my extract, because my summary of their summary could be biased.<br />
<br />
6. Should the original authors have included more quantitative results in their abstract?<br />
<br />
Submitted by Steve Simon</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_14&diff=2237Chance News 142006-02-27T03:47:00Z<p>Thekohser: /* Another record jackpot for the Powerball lottery */</p>
<hr />
<div>==Quotation== <br />
<blockquote>The [Supreme] Court concluded that mental health professionals' predictions were "not always wrong...only most of the time."</blockquote><br />
<div align="right">Gerd Gigerenzer <br><br />
</div><br />
<br />
==Forsooth==<br />
<br />
<br />
<br />
<blockquote> In theory, if you were to buy 50 tickets and your neighbor bought one, neither of you would have a better or worse chance of winning, We like to say it only takes one ticket to win."<br />
</blockquote><br />
<br />
<div align="right">Brian Rockey, a spokesman for the Nebraska Lottery<br><br />
in a discussion of the record Powerball jackpot of 360 million dollars.<br><br />
Omaha World-Herald (Nebraska) February 18, 2007 Pg. 01A. </div><br />
<br />
==Gerd Gigerenzer's Calculated Risks Revisited==<br />
[http://www.dartmouth.edu/%7Echance/chance_news/recent_news/chance_news_11.03.html#item10 Chance News 11.03] had a lengthy and very positive review of Gerd Gigerenzer's book '''Calculated Risks: How To Know When Numbers Deceive You'''.<br />
Readers are urged to download that excellent review because of the information contained. However, the book is so good and so persuasive that it is worth another look in order to alert readers to some other aspects of the book and how it relates to subsequent events.<br />
<br />
The aforementioned review did not mention the abundant number of actual, real-world incidents cited in which doctors, lawyers and social workers, not to mention patients, clients and jurors, were unable to unscramble the difference between P(X| Y) and P(Y| X). Also not mentioned was Gigerenzer's dim view of screening for breast cancer and prostate cancer. Screening may be defined, according to H. Gilbert Welch, as "the systematic examination of asymptomatic people to detect and treat disease." See [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_12#Screening Chance News 12] for a review of Welch's 2004 book '''Should I Be Tested For Cancer? Maybe Not And Here's Why'''. Welch echoes and amplifies Gigerenzer contention that (mass) screening is counterproductive, especially when there is little evidence that a cure exists. Just to complicate matters, however, see [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_8#Mammograms_Validated_as_Key_in_Cancer_Fight "Mammograms validated as key in cancer fight"] in Chance News 8 which indicates that mammography screening does reduce the death rate of breast cancer, . Unfortunately, the article in the ''New England Journal of Medicine'' referred to does not explain why mammogram screening is deemed responsible for 28 to 65% of the 24% drop in the breast cancer death rate.<br />
Gigerenzer would prefer, and this is one of his main points, that any statistical data be given in counts rather than in percentages, especially percentages without a base rate, such as relative risk which he views as the most misleading. <br />
<center><table width="100%" border="1"><br />
<tr><br />
<th>Treatment</th><br />
<th>Deaths per 1000 women</th> <br />
<tr><br />
<td>No mammography screening</td><br />
<th>4</th><br />
</tr><br />
<tr><br />
<td>Mammography screening</td><br />
<th>3</th><br />
</tr><br />
</table></center><br />
<br />
Consequently, there is "a 25 percent relative risk reduction." He would prefer focusing on the difference in the number of deaths which yields the more revealing and perhaps more honest statement: "The absolute risk reduction is 4 minus 3, that is, 1 out of 1000 women (which corresponds to .1 percent)." However, "Counting on their clients' innumeracy, organizations that want to impress upon clients the benefits of treatment generally report them in terms of relative risk reduction...applicants [for grants] often feel compelled to report relative risk reductions because they sound more impressive." Although he did not use this example, one's relative "risk" of winning the lottery is infinitely greater if one buys a ticket, yet one's absolute "risk" of winning has hardly improved at all.<br />
<br />
Most of his numerical examples are typified by his discussion of the cartoon given below <br />
<br />
<center>[[Image:gigerenzer1.gif|500px]]</center><br />
<br />
which indicates the superiority of dealing with counts. Note that "H" represents having the disease and "D" represents a diagnosis having the symptom as seen by testing positive. Characteristically, there is a large number in the population who do not have the disease and because of the possibility of a wrong classification, the number of false positives (99) outweighs the number of true positives (8) resulting in P(disease| symptom) being much lower (8/(8+99)) than P(symptom| disease) (.8). This type of result, low probability of disease given symptom, is true even when ".8" is replaced by a number much closer to 1 provided there are many more who do not have the disease.<br />
<br />
Here is an example he did not consider but it also illustrates the superiority of dealing with counts. Instead of two populations--diseased and healthy--which are greatly different in size, consider Boys and Girls and the desire to predict gender based on some simple test. Assume that 50% of births are Boys so that P(Boy) = P(Girl) = 1/2. A simple, inexpensive, non-invasive gender-testing procedure indicates that it is "perfect" for boys, P(Test Boy| Boy) = 1, implying P(Test Girl| Boy) = 0. Unfortunately, this simple, inexpensive, non-invasive gender-testing procedure for girls is a "coin toss," P(Test Girl| Girl) = P(Test Boy| Girl) = 1/2. Application of Bayes theorem yields what seems to be a strange inversion, P(Boy| Test Boy) = 2/3 and P(Girl| Test Girl) = 1. That is, somehow, "perfection" switched from Boy to Girl. The test is perfect in "confirming" that a Boy is a Boy and has a 50% error rate in confirming that a Girl is a Girl. The test is perfect in "predicting" that a person who tests as a girl is in fact a girl but has 33% error rate in predicting that a person who tests as a Boy is in fact a Boy. Thus, the term perfect is ambiguous. Perfection in confirmation, i.e., the test conditional on the gender, does not mean perfection in prediction, i.e., the gender conditional on the test.<br />
<br />
Some of the puzzlement disappears if we deal with counts; the table below is equivalent to Gigerenzer's "tree" diagram. Assume 50 Boys and 50 Girls to start with. Every one of the 50 Boys will test as a Boy--none of the Boys test as a Girl; of the 50 Girls, 25 will test as a Boy and 25 will test as a girl. Therefore, P(Girl| Test Girl) = 1. One is tempted to to explain the switch by using the lingo of medical testing: false positives, false negatives, sensitivity, specificity, positive predictive value, negative predictive value. However, one hesitates to designate either gender as diseased even though the mathematics is the same.<br />
<center><table width="75%" border="1"><br />
<tr><br />
<th>&nbsp;</th><br />
<th>Test Boy</th><br />
<th>Test Girl</th><br />
<th>Total</th><br />
</tr><br />
<tr><br />
<th>Boy</th><br />
<th>50</th><br />
<th>0</th><br />
<th>50</th><br />
</tr><br />
<tr><br />
<th>Girl</th><br />
<th>25</th><br />
<th>25</th><br />
<th>50</th><br />
</tr><br />
</table></center><br />
<br />
Gigerenzer rightly concludes that the language of statistics is not natural for most individuals. Perhaps the puzzlement in this specific example is at least partly due to the natural language known as English. Boys, Girls, Test Boys and Test Girls are too confusing. . Replace "Boy" by "Norwegian" and "Girl" by "German" and assume that there are as many Norwegians as Germans. Let every Norwegian be "Blond," so that P(Blond| Norwegian) = 1 and only half the Germans are Blond. Thus, P(German| Not Blond) =1; the switch, P(German| Not Blond) = P(Blond| Norwegian) = 1, is rather obvious. Is the this situation easier to understand because of the linguistics--hair color and ethnicity are easily distinct as Test Boy and Boy are not?<br />
<br />
===DISCUSSION QUESTIONS===<br />
<br />
1. Gigerenzer has a chapter entitled, "(Un)Informed Consent." Based on your experience, what do you imagine the chapter contains?<br />
<br />
2. A drawing of two tables (that is, physical tables on which things are placed) appears on page 10. He claims the tables (due to Roger Shepard) are identical in size and shape. After staring at them in disbelief of the claim, how would you verify the contention?<br />
<br />
3. Physicians sometime make the following type of statement:"Never mind the statistics, I treat every patient as an individual." Defend this assertion. Criticize this assertion.<br />
<br />
4. The physicist, Lord Rutherford, is reputed to have said, " If your experiment, needs statistics you ought to have done a better experiment." Defend and criticize Lord Rutherford.<br />
<br />
5. Assume an asymptomatic woman has a mammogram which looks suspicious and then a biopsy which is negative. Would she be grateful for the clean bill of health or would she become an advocate who opposes (mass) screening? Suppose instead we assume a man has a suspiciously high PSA and the painful multiple biopsies (6-12 "sticks") are all negative. Would he be grateful for the clean bill of health or would he become an advocate who opposes (mass) screening? <br />
<br />
6. Calculated Risks also deals with the risk to the physician making a recommendation and a diagnosis. Discuss why in our present-day litigious society the risks to the physician (who may or may not recommend a test or may or may not make a diagnosis) are not symmetrical. Along these lines, who are the vested interests involved in maintaining screening and testing?<br />
<br />
7. Revisit the Boy/Girl scenario but now the test always says Boy regardless of gender, P(Test Boy| Boy) = P(Test Boy| Girl) = 1. Complete the table for this version. Obviously, this test has the advantage of being extremely simple, cost-free and non-invasive. Use either the Probability Format or the Frequency Format to comment on the statistical worthiness of this test.<br />
<br />
Submitted by Paul Alper<br />
<br />
==More medical studies the conflict with previous studies==<br />
<br />
[http://www.nytimes.com/2006/02/08/health/08fat.html?_r=1&oref=slogin Low-fat diet does not cut health risks, Study finds]<br><br />
''New York Times'', Feb. 8, 2006<br><br />
Gina Kolata<br />
<br />
[http://www.usatoday.com/news/health/2006-02-07-diet-fat-women_x.htm Cutting fat alone isn't enough, women advised]<br><br />
''USA TODAY'', Feb, 7, 2006<br><br />
Rita Rubin<br />
<br />
[http://www.post-gazette.com/pg/06040/652708.stm Popular herb shows no benefit for prostate]<br><br />
Wall street journal, Feb. 9, 2006<br><br />
Syllvia Pagan Westphal<br />
<br />
In the ''New York Times'' article we read:<br />
<br />
<blockquote>The largest study ever to ask whether a low-fat diet reduces the risk of getting cancer or heart disease has found that the diet has no effect.<br><br><br />
<br />
The $415 million federal study involved nearly 49,000 women ages 50 to 79 who were followed for eight years. In the end, those assigned to a low-fat diet had the same rates of breast cancer, colon cancer, heart attacks and strokes as those who ate whatever they pleased, researchers are reporting today.</blockquote><br />
<br />
In the ''Wall Street Journal'' article we read:<br />
<br />
<blockquote>Saw palmetto, an herbal supplement taken by 2.5 million Americans for problems with enlargement of the prostate gland, is no more effective than a placebo in alleviating the condition, according to a new study<br><br><br />
<br />
The perception that saw palmetto works had been supported by a number of clinical trials over the years. A comprehensive 2002 analysis of 21 trials involving over 3,000 men found that studies credited saw palmetto with providing "mild to moderate improvement in symptoms with fewer adverse events than finasteride (approved by the Food and Drug Administration to treat benign enlargement).</blockquote><br />
<br />
The saw palmetto study was reported in the ''New England Journal of Medicine'' February 9, 2006 and the low-fat diet study was reported in ''Jama'', February 8, 2006.<br />
<br />
The saw palmetto study had 225 participants randomized to give 112 saw palmetto and 113 placebo and the study lasted from July 2001 to May 2003.<br />
<br />
So once more the general public will wonder what the truth is. Commenting on the diet study Berkeley statistician David Freedmn is quoted as saying that the studies were well designed and should be taken seriously.<br />
<br />
Two of the 32 authors of the study, Judith Hsia, professor of medicine at George Washington University in Washington, D.C. and Ross Prentice, professor of biostatistics at the University of Washington in Seattle, were interviewed by Ira Flato on NPR's Talk of the Nation Friday Science program February 10, 2006. You can listen to them trying to do damage control [http://www.npr.org/templates/story/story.php?storyId=5200525 here] . The say that women should certainly not quit trying to control their diet. They point out that the study did not distinquish between "good" and "bad" fats. Prentice remarks that the incidence rate of breast cancer was 9% less in control group than in the placebo group. When Ira remarks that the study said that the difference was not significant, Prentice replied that you have to understand what statistical signficance meant and adds that if it were 10% it would have been signficant. <br />
<br />
The authors of the paper also comment that the study was not able to continue for the length of time originally planned and since the trend for the incidence of Breast cancer was in the right direction so it is possible that the difference might be significant over the longer time. Here is a graphic from the ''Jama'' article that shows the difference in the incident rates over time http://www.dartmouth.edu/~chance/chance_news/for_chance_news/wiki/diet.png.<br />
<br />
On Feb. 14 Kolata wrote in the ''Times'' a sequal [http://www.nytimes.com/2006/02/14/health/14fat.html Maybe you're not what you eat] to her Feb 8 article where she attempts to explain the conflicting views of the results of the Women's study. You will find [http://www.nytimes.com/2006/02/16/science/17askscience.html here] her answers to readers questions relating to her Feb. 14 article.<br />
<br />
Then in the Times on Feb. 16 she wrote an article [http://www.nytimes.com/2006/02/16/health/16bones.htm Big study finds no clear benefit of calcium pills] about another study based on the Women's study. She writes:<br />
<br />
<blockquote>The $18 million study was part of the Women's Health Initiative, a large federal project whose results have confounded some popular beliefs and raised questions about public health messages that had been addressed to the entire population.<br><br><br />
<br />
In the new study, the participants were randomly assigned to take 1,000 milligrams of calcium and 400 international units of vitamin D a day, or to take placebos, and were followed for seven years. Researchers looked for effects on bone density, fractures and colorectal cancer. The lack of an effect on colorectal cancer over the seven years was so clear that it has aroused little debate. But the effect on bones is another story.<br><br><br />
<br />
Osteoporosis specialists said the study, published today in the New England Journal of Medicine, was likely to put a dent in what has become a widespread medical practice of recommending that all women take calcium and vitamin D supplements starting at menopause if not sooner, as a sort of insurance policy against osteoporosis. But beyond that there is no agreement on what, if anything, healthy women should do.</blockquote><br />
<br />
This led to still another ''New York Times'' article by Denise Grady Feb. 19, 2006 <br />
[http://www.nytimes.com/2006/02/19/health/19health.html?ex=1140584400&en=9daef52512f69cfc&ei=507 Women's health sudies leaves questions in place of certainty] This article begins with:<br />
<br />
<blockquote>So what do women do now? The results of two major studies over the past two weeks have questioned the value of two widely recommended measures: calcium pills and vitamin D to prevent broken bones, and low-fat diets to ward off heart disease and breast and colon cancer.</blockquote><br />
<br />
The article discusses the conflicts between statisticians who are willing to accept the outcomes of the study and researchers who want to look at subgroups to try to argue that despite the lack of significance one can see hopeful signs. Statistician Susan Ellenberg remarks:<br />
<br />
The probability that you will see a spuriously positive effect gets very big very quickly.<br />
<br />
Ellenberg quotes another statistician, Richard Peto of Oxford University, who said of subgroups:<br />
<br />
<blockquote>You should always do them but you should never believe them.</blockquote><br />
<br />
You will also find in this article a nice graphic summerizing the results of the Women's study relating to low-fact diets and vitamin D.<br />
<br />
===Further reading===<br />
The low-fat diet study has attracted a lot of attention from bloggers.<br />
* [http://blog.proteinpower.com/drmike/archives/2006/02/man_bites_dog.html Man Bites Dog] and [http://blog.proteinpower.com/drmike/archives/2006/02/man_bites_dog_i.html Man Bites Dog II], Michael R. Eades, M.D. offers a critical review of the design of the study.<br />
* [http://www.weightoftheevidence.com/ Regina Wilshire's blog] on why we don't need more time and/or more studies to 'prove' that low-fat dieting really works.<br />
<br />
==A day in the life of a human rights statistician==<br />
[http://www.wired.com/news/technology/1,70196-0.html Coders Bare Invasion Death Count], By Ann Harrison, Wired News, 9-Feb-06.<br><br />
[http://www.boingboing.net/2006/02/11/how_statistics_caugh.html How statistics caught Indonesia's war-criminals ], Cory Doctorow, BoingBoing.net<br />
<br />
A group of determined programmers and statisticians,<br />
the [http://www.hrdag.org/about/ Human Rights Data Analysis Group], released a [http://www.hrdag.org/resources/timor_chapter_graphs/timor_chapter_page_01.shtml report] documenting over civilian deaths in the former Portuguese colony, which occurred from a year prior to the Indonesian army's invasion in 1975, to the country's 1999 independence referendum that formally ended the occupation.<br />
[http://www.hrdag.org/about/timor-leste.shtml Statistical analysis] establishes that at least 102,800 (+/- 11,000) Timorese died as a result of the conflict. Approximately 18,600 (+/- 1000) Timorese were killed or disappeared, while the remainder died due to hunger and illness in excess of what would be expected due to peacetime mortality. <br />
<br />
Group director Patrick Ball says <br />
<blockquote><br />
By having an accurate statistical picture of the suffering, we can draw conclusions about what the causes of the violence might have been and identify likely perpetrators with a claim based on thousands of witnesses.<br />
</blockquote><br />
<br />
The group established three datasets that integrated quantitative methods into broader truth seeking activities. These datasets included:<br />
* The commission's statement-taking process, which collected almost 8,000 narrative testimonies from people in every sub-district; <br />
* A census of all public graveyards in the country (encompassing approximately 319,000 gravestones); <br />
* A retrospective mortality survey drawing on a probability sample of approximately 1,400 households throughout the thirteen districts of Timor-Leste. <br />
In establishing these data, HRDAG and the Commission for Reception, Truth and Reconciliation in East Timor (CAVR) pioneered a number of new techniques and methods. <br />
No other truth commission has ever undertaken a retrospective mortality survey. <br />
While gravestone information for mortality estimation has been used by historical demographers for mortality estimations, this is the first time that a human rights project has employed such methods. <br />
These projects were so large that HRDAG developed automated techniques to link multiple reports of the same death - a key component of [http://www.hrdag.org/resources/mult_systems_est.shtml multiple systems estimation],<br />
a technique that uses two separately collected but incomplete lists of a population to estimate the total population size.<br />
<br />
HRDAG uses the multiple systems estimation technique in human rights cases to project the total number of violations, including those that were never documented. This information is vital to producing a complete accurate historical record of the violations and to provide evidence at the trial of the architects of large-scale human rights abuses.<br />
In order to make statistical inferences from multiple systems estimation, it is necessary to:<br />
* Identify overlapping reports <br />
* Control for bias and variation in coverage rates <br />
* Estimate the total magnitude <br />
<br />
Ball has spent the last 15 years building systems and conducting qualitative analysis for large-scale human rights data projects around the world.<br />
HRGAD researchers used comparative analysis of the datasets to uncover patterns of deaths and build objective evidence of abuses. The team also developed an array of descriptive statistical analysis profiling the scale, pattern and structure of torture, ill-treatment, arbitrary detention and sexual violations. <br />
In order to estimate what was missing from the data, the HRDAG developed software to link multiple reports of the same death in a technique called record linkage. <br />
They then used multiple systems estimation to calculate the number of deaths that no one remembered. <br />
<br />
Romesh Silva, a HRDAG field statistician who led the design and implementation of the project's data, says<br />
<blockquote><br />
The Indonesian military has persistently argued that excess mortality in Timor due to its occupation of Timor was zero.<br />
This claim can now be tested empirically and transparently with the tools of science instead of merely being debated with the tools of political rhetoric.<br />
</blockquote><br />
<br />
The final report of the CAVR was handed over to the President of Timor-Leste on 31 October 2005. The President of Timor-Leste then tabled the report at a special sitting of Timor-Leste's National Parliament on 28 November, 2005 - which coincided with the 30th anniversary celebrations of Timor's Proclamation of Independence. <br />
<br />
===Further reading===<br />
* [http://www.hrdag.org/about/ The Human Rights Data Analysis Group (HRDAG)] develops information technology solutions and statistical techniques to help human rights advocates build evidence-based arguments.] See the [http://www.hrdag.org/about/faqs.shtml FAQ] for more info.<br />
* [http://www.hrdag.org/resources/timor_chapter_graphs/timor_chapter_page_01.shtml The Profile of Human Rights Violations in Timor-Leste, 1974-1999.] A Report by the Benetech Human Rights Data Analysis Group to the Commission on Reception, Truth and Reconciliation of Timor-Leste. 9 February 2006.<br />
* [http://www.hrdag.org/about/romesh_silva.shtml Romesh Silva] and [http://www.hrdag.org/about/patrick_ball.shtml Patrick Ball] designed and conducted the statistical analysis and wrote this report. Their on-line profiles provide more information about their statistical work and the awards that they have received. The are also profiles of other [http://www.hrdag.org/about/people.shtml statistical consultants] at HRDAG.<br />
Two short papers by Romesh and Ball are worth reading:<br />
* [http://paa2006.princeton.edu/download.aspx?submissionId=60827 The Demography of Large-Scale Human Rights Atrocities: Integrating demographic and statistical analysis into post-conflict historical clarification in Timor-Leste.] Romesh Silva and Patrick Ball. A 5-page paper presented at the 2006 meetings of the Population Association of America.<br />
* [http://www.austms.org.au/Publ/Gazette/2005/May05/careersilva.pdf My brilliant career - Quantitative Data Analysis and Large-Scale Human Rights Violations: An Example of Applied Statistics at the Grassroots.] Romesh Silva. Gazette of the Australian Mathematical Society. Canberra (Australia). Volume 32, Number 2, May 2005. A 5-page paper on where a mathematics education can lead you. <br />
** "in the late 1990’s as I was completing my honors degree in statistics at UNSW, I became increasingly involved with Amnesty International ... I began to wonder how I might be able to directly apply my mathematical education and quantitative skills to international human rights. ... As the field of human rights statistics is relatively new, our main challenge remains in attracting more mathematicians and statisticians to work in this area and also communicating to the human rights field how quantitative data analysis can contribute to accountability and truthtelling processes."<br />
<br />
Submitted by John Gavin.<br />
<br />
==Another record jackpot for the Powerball lottery==<br />
[http://www.startribune.com/535/story/247617.html Elusiveness of Powerball is revealed in the math]<br><br />
Minneapolis Star Tribune, Feb. 15, 2006<br><br />
Mike Meyers<br />
<br />
[http://www.latimes.com/news/columnists/la-oe-daum25feb25,1,5399378.column?coll=la-news-columns&ctrack=1&cset=true Who's the idiot now?]<br><br />
''Los Angeles Times'', Feb. 25, 2006<br><br />
Meghan Doum.<br />
<br />
When a powerball jackpot nears a new record the media asks experts to comment on what the odds are and to explain how unlikely you are to win a lottery. See [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_8#A_record_powerball_lottery_jackpot Chance News 8] for interesting comments of two Minnesota mathematicians related to the October 22, 2005 record $340 million powerball jackpot. For his article related to the current record $365 jackpot, Meyers consulted [http://www.math.temple.edu/~paulos/ John Paulos] author of the bestselling book, "Innumeracy" and a monthly column [http://abcnews.go.com/Technology/WhosCounting/story?id=1560771 Who's Counting] for ABCNews.com. <br />
<br />
We read:<br />
<br />
<blockquote> Paulos says lotteries have always owed their appeal to people's loose grip of math and recalled a line from Voltaire: "Lotteries are a tax on stupidity."<br><br><br />
<br />
Paulos once tore up a Powerball ticket on the eve of a drawing in front of an audience. "They all gasped as if I just slashed the Mona Lisa," he said. </blockquote><br />
<br />
While the Voltaire quote is on many websites and usually attributed to Voltaire our librarians were unable to find it's source. Perhaps a reader can provide this. However in our search we did find a similar quotation:<br />
<br />
<center>A lottery is a taxation, Upon all the fools in Creation;<br><br />
And Heav'n be prais'd, It is easily rais'd, <br><br />
Credulity's always in fashion; <br><br />
For, folly's a fund, Will never lose ground,<br><br />
While fools are so rife in the Nation.</center><br />
<div align="right">Henry Fiellding 1707-54<br><br />
</div><br />
<br />
From Wikipedia we read:<br />
<br />
<blockquote>'''Henry Fielding''' was an English novelist and dramatist known for his rich earthy humor and satirical prowess and as the author of the novel ''Tom Jones''.</blockquote><br />
<br />
The quotation comes from Fielding's play [http://www.ebookmall.com/ebook/169052-ebook.htm ''The Lottery, a farce''] (1724)<br />
<br />
In her ''Los Angelas Times'' article [http://www.latimes.com/news/columnists/la-oe-daum25feb25,1,5399378.column?coll=la-news-columns&ctrack=1&cset=true"Who's the idiot now?] about the winners of the current record lottery columnest Meghan Daum writes:<br />
<blockquote>On Wednesday morning in Lincoln, Neb., after four days of speculation about who had won the biggest jackpot in Powerball history, eight employees of a ConAgra ham processing plant came forward and identified themselves as the winners of the $365-million purse. As lottery stories go, this is about as heartwarming as it gets. Two of the winners are immigrants from Vietnam and one is a political refugee from the Republic of Congo -- and all worked the second and third shifts, some clocking as many as 70 hours a week. There is probably no jobsite as gruesome as a meatpacking house. If anyone deserves an express ticket to a new life, it's these folks. </blockquote><br />
<br />
Equally moving is to listen [http://www.latimes.com/news/columnists/la-oe-daum25feb25,1,5399378.column?coll=la-news-columns&ctrack=1&cset=true here] to the winners answers in an interview by Sara McCammon on NPR ''All things considered'' Feb. 22, 2006.<br />
<br />
==Europe's statisticians are too gloomy==<br />
[http://www.economist.com/finance/displayStory.cfm?story_id=5531335 A numbers racket], The Economist, 18-Feb-06.<br><br />
[http://www.economist.com/displaystory.cfm?story_id=E1_VVDQTDP How to measure economies], The Economist, 9-Feb-2006 (subscription required).<br />
<br />
The first article highlights how statistical biases can influence perceptions of economic growth.<br />
The second gives more information about the merits of [http://en.wikipedia.org/wiki/Gross_domestic_product gross domestic product (GDP)] relative to other economic indicators.<br />
<br />
GDP per head is the most commonly used measure of a country's success. <br />
It was primarily developed as a planning tool to measure productivity during World War II<br />
as it measures value of goods and services produced by the residents of a country.<br />
A nation's well-being depends on factors not covered by GDP, such as leisure time, income inequality and the quality of the envirnoment but GDP was never intended to measure welfare.<br />
For most purposes, it the best available indicator on a timely basis so governments worry about how to boost their GDP growth.<br />
<br />
There is a wide gap between America's and Europe's GPD per head.<br />
Since the start of [http://en.wikipedia.org/wiki/European_Monetary_Union European Monetary Union] in 1999, revisions to [http://en.wikipedia.org/wiki/Gross_domestic_product gross domestic product (GDP)] growth have almost always been upwards. In contrast, revisions in America have tended to be downwards. The initial figures which grab newspaper headlines therefore exaggerate Europe's economic underperformance. <br />
<br />
The Economist resists the obvious conclusion:<br />
<blockquote><br />
Discounting the obvious explanation that American statisticians are born optimists, it is unclear what lies behind the consistent direction of these revisions. <br />
</blockquote><br />
<br />
This article is based on a paper by Kevin Daly, an economist at Goldman Sachs.<br />
He calculates that, based on the GDP-growth figures first published in each quarter, the euro area would have grown by an annual average of only 1.6% in the six years to 2004. Yet the latest figures put the growth rate at 2.0%. <br />
In contrast, the first published figures gave America an average growth rate of 3.1%; but that has now been shaved down to 2.8%. The revisions have cut the reported gap between growth rates in America and the euro area in half. As a result, the euro area's GDP per head has in fact grown at the same pace as America's. <br />
<br />
The Economist goes on to comment:<br />
<blockquote><br />
Europe could rejoice in further upward revisions to growth if its governments were to adopt American statistical practices. Price deflators there take more account of improvements in the quality of goods, such as computers, and thus a given rise in nominal spending implies faster growth in real terms. By using higher inflation rates, the euro area understates its growth relative to America's. In addition, American statisticians consider firms' spending on software that is written in-house to be investment, while in the euro area it is often counted as an expense and so is excluded from final output. The surge in software spending has therefore inflated America's relative growth. <br />
<br><br />
<br><br />
On past experience, Europe's statisticians should add half a percentage point to their first guesses of GDP growth. By also switching to American practices, they could boost growth even further. Instead, their cautious ways are making Europe's economies look more dismal than they are, and gloomy headlines are discouraging consumers from spending. Perhaps Europe should outsource the compilation of its statistics to America, and then watch the boom.<br />
</blockquote><br />
<br />
The second Economist article says that the OECD is encouraging governments to move from relying <br />
on just one indicator. Alternatives, like [http://en.wikipedia.org/wiki/Gross_national_income gross] or net national income suggest that the gap between American and European growth rates may much smaller.<br />
<br />
===Further reading===<br />
[http://www.sbe.co.uk/pdfs/articles/34_3_Daly.pdf Has Euroland Performed That Badly?], Kevin Daly, Golman Sachs. Daly says <br />
<blockquote><br />
Euroland productivity when measured appropriately is not only close to US levels but, over the past ten years as a whole, its growth has continued to surpass that of the US. The<br />
US’s superior GDP performance over this period has not been attributable to faster productivity growth but to a more rapidly expanding labour force that is prepared to work longer hours.<br />
</blockquote><br />
<br />
Submitted by John Gavin.<br />
<br />
==Single and not so carefree==<br />
<br />
Premature mortality among lone fathers and childless men. Ringback Weitoft G, Burstrom B, Rosen M. Soc Sci Med. 2004 Oct;59(7):1449-59.<br />
<br />
This study is a couple of years old, but it is interesting in itself and in how it was reported by a conservative advocacy group. I have not read the full article, so I can only comment on the abstract, which is [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15246173&dopt=Citation available on PubMed].<br />
<br />
These researchers studied 682,919 men and divided them into five groups (lone fathers with custody of their child/children, lone fathers without custody, childless men with a wife, childless men without a wife, and men with a wife and men with a wife and child/children. The last group was the comparison group for all comparisons. They analyzed deaths in these groups from 1991 to 2000.<br />
<br />
<blockquote>"The results suggest that lone non-custodial fathers and lone childless men face the greatest increase in risks, especially from injury and addiction, and also from all-cause mortality and ischaemic heart disease. Being a lone custodial father also entails increased risk, although generally to a much lesser extent, and not for all outcomes. The elevated risks found in all the subgroups considered diminished substantially when proxy variables to control for health-selection effects and socioeconomic circumstances were added to the initial model. Risks fell most in response to introduction of the socioeconomic variables, but health selection also played a major role, mostly in the cases of lone non-custodial fathers and lone childless men. However, even following these adjustments, significant risk increases, although greatly attenuated, remained for all the subgroups."</blockquote><br />
<br />
No mention was made about adjustment for age, but this would have to be done because there is almost certainly a large disparity in the age of men with and without children.<br />
<br />
I became aware of this paper when my brother-in-law sent me an email describing the study that was produced by [http://www.profam.org/Default.htm The Howard Center for Family, Religion, & Society]. This group is located in Rockford, Illinois and does not seem to be associated with Howard University. This group advocates for many conservative family values causes, and opposes gay marriage and no fault divorce. They regularly summarize research studies that support their political viewpoint. There are many other organizations, of course, that advocate viewpoints of all types and they also summarize studies that favor their political outlook.<br />
<br />
There was a large discrepancy, however, in the information provided in the abstract and the information provided by this website. In particular, the website lists actual numbers from the publication itself while the abstract did not report any quantitative results.<br />
<br />
<blockquote>Sharp differences in mortality rates separated these five groups, with men living alone, apart from their children, at greatest risk of premature death. In comparison with men living with a wife (or partner) and their children, fathers living alone—without spouse (or partner) and apart from their children—experienced “almost 4 times as great a risk of all-cause mortality, 10 times of death from external violence, 13 times from fall and poisoning, almost 5 times from suicide, and 19 times from addiction.”</blockquote><br />
<br />
You can read [http://www.profam.org/pub/nr/nr_1811.htm#Men_Dying_Alone the full summary] which does mention the attenuation of these effects after statistical adjustments, but does not report the adjusted rates, only the unadjusted ratios.<br />
<br />
===Questions===<br />
<br />
1. What do you think the "proxy variables to control for health-selection effects and socioeconomic circumstances" are?<br />
<br />
2. Why is it important to adjust for these variables and why are proxies needed?<br />
<br />
3. List some covariates which could possibly be imbalanced between the five groups studied other than health selection effects, socioeconomic circumstances, and presumably age. Could any of these influence mortality results?<br />
<br />
4. Why would a reviewer be interested in the unadjusted ratios rather than the adjusted ratios?<br />
<br />
5. Do you feel that the Howard Center for Family, Religion, & Society summary is a fair and balanced representation of the work by Ringback Weitoft et al? Be sure to read [http://www.profam.org/pub/nr/nr_1811.htm#Men_Dying_Alone the full summary] rather than my extract, because my summary of their summary could be biased.<br />
<br />
6. Should the original authors have included more quantitative results in their abstract?<br />
<br />
Submitted by Steve Simon</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_14&diff=2236Chance News 142006-02-27T03:46:13Z<p>Thekohser: /* Another record jackpot for the Powerball lottery */</p>
<hr />
<div>==Quotation== <br />
<blockquote>The [Supreme] Court concluded that mental health professionals' predictions were "not always wrong...only most of the time."</blockquote><br />
<div align="right">Gerd Gigerenzer <br><br />
</div><br />
<br />
==Forsooth==<br />
<br />
<br />
<br />
<blockquote> In theory, if you were to buy 50 tickets and your neighbor bought one, neither of you would have a better or worse chance of winning, We like to say it only takes one ticket to win."<br />
</blockquote><br />
<br />
<div align="right">Brian Rockey, a spokesman for the Nebraska Lottery<br><br />
in a discussion of the record Powerball jackpot of 360 million dollars.<br><br />
Omaha World-Herald (Nebraska) February 18, 2007 Pg. 01A. </div><br />
<br />
==Gerd Gigerenzer's Calculated Risks Revisited==<br />
[http://www.dartmouth.edu/%7Echance/chance_news/recent_news/chance_news_11.03.html#item10 Chance News 11.03] had a lengthy and very positive review of Gerd Gigerenzer's book '''Calculated Risks: How To Know When Numbers Deceive You'''.<br />
Readers are urged to download that excellent review because of the information contained. However, the book is so good and so persuasive that it is worth another look in order to alert readers to some other aspects of the book and how it relates to subsequent events.<br />
<br />
The aforementioned review did not mention the abundant number of actual, real-world incidents cited in which doctors, lawyers and social workers, not to mention patients, clients and jurors, were unable to unscramble the difference between P(X| Y) and P(Y| X). Also not mentioned was Gigerenzer's dim view of screening for breast cancer and prostate cancer. Screening may be defined, according to H. Gilbert Welch, as "the systematic examination of asymptomatic people to detect and treat disease." See [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_12#Screening Chance News 12] for a review of Welch's 2004 book '''Should I Be Tested For Cancer? Maybe Not And Here's Why'''. Welch echoes and amplifies Gigerenzer contention that (mass) screening is counterproductive, especially when there is little evidence that a cure exists. Just to complicate matters, however, see [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_8#Mammograms_Validated_as_Key_in_Cancer_Fight "Mammograms validated as key in cancer fight"] in Chance News 8 which indicates that mammography screening does reduce the death rate of breast cancer, . Unfortunately, the article in the ''New England Journal of Medicine'' referred to does not explain why mammogram screening is deemed responsible for 28 to 65% of the 24% drop in the breast cancer death rate.<br />
Gigerenzer would prefer, and this is one of his main points, that any statistical data be given in counts rather than in percentages, especially percentages without a base rate, such as relative risk which he views as the most misleading. <br />
<center><table width="100%" border="1"><br />
<tr><br />
<th>Treatment</th><br />
<th>Deaths per 1000 women</th> <br />
<tr><br />
<td>No mammography screening</td><br />
<th>4</th><br />
</tr><br />
<tr><br />
<td>Mammography screening</td><br />
<th>3</th><br />
</tr><br />
</table></center><br />
<br />
Consequently, there is "a 25 percent relative risk reduction." He would prefer focusing on the difference in the number of deaths which yields the more revealing and perhaps more honest statement: "The absolute risk reduction is 4 minus 3, that is, 1 out of 1000 women (which corresponds to .1 percent)." However, "Counting on their clients' innumeracy, organizations that want to impress upon clients the benefits of treatment generally report them in terms of relative risk reduction...applicants [for grants] often feel compelled to report relative risk reductions because they sound more impressive." Although he did not use this example, one's relative "risk" of winning the lottery is infinitely greater if one buys a ticket, yet one's absolute "risk" of winning has hardly improved at all.<br />
<br />
Most of his numerical examples are typified by his discussion of the cartoon given below <br />
<br />
<center>[[Image:gigerenzer1.gif|500px]]</center><br />
<br />
which indicates the superiority of dealing with counts. Note that "H" represents having the disease and "D" represents a diagnosis having the symptom as seen by testing positive. Characteristically, there is a large number in the population who do not have the disease and because of the possibility of a wrong classification, the number of false positives (99) outweighs the number of true positives (8) resulting in P(disease| symptom) being much lower (8/(8+99)) than P(symptom| disease) (.8). This type of result, low probability of disease given symptom, is true even when ".8" is replaced by a number much closer to 1 provided there are many more who do not have the disease.<br />
<br />
Here is an example he did not consider but it also illustrates the superiority of dealing with counts. Instead of two populations--diseased and healthy--which are greatly different in size, consider Boys and Girls and the desire to predict gender based on some simple test. Assume that 50% of births are Boys so that P(Boy) = P(Girl) = 1/2. A simple, inexpensive, non-invasive gender-testing procedure indicates that it is "perfect" for boys, P(Test Boy| Boy) = 1, implying P(Test Girl| Boy) = 0. Unfortunately, this simple, inexpensive, non-invasive gender-testing procedure for girls is a "coin toss," P(Test Girl| Girl) = P(Test Boy| Girl) = 1/2. Application of Bayes theorem yields what seems to be a strange inversion, P(Boy| Test Boy) = 2/3 and P(Girl| Test Girl) = 1. That is, somehow, "perfection" switched from Boy to Girl. The test is perfect in "confirming" that a Boy is a Boy and has a 50% error rate in confirming that a Girl is a Girl. The test is perfect in "predicting" that a person who tests as a girl is in fact a girl but has 33% error rate in predicting that a person who tests as a Boy is in fact a Boy. Thus, the term perfect is ambiguous. Perfection in confirmation, i.e., the test conditional on the gender, does not mean perfection in prediction, i.e., the gender conditional on the test.<br />
<br />
Some of the puzzlement disappears if we deal with counts; the table below is equivalent to Gigerenzer's "tree" diagram. Assume 50 Boys and 50 Girls to start with. Every one of the 50 Boys will test as a Boy--none of the Boys test as a Girl; of the 50 Girls, 25 will test as a Boy and 25 will test as a girl. Therefore, P(Girl| Test Girl) = 1. One is tempted to to explain the switch by using the lingo of medical testing: false positives, false negatives, sensitivity, specificity, positive predictive value, negative predictive value. However, one hesitates to designate either gender as diseased even though the mathematics is the same.<br />
<center><table width="75%" border="1"><br />
<tr><br />
<th>&nbsp;</th><br />
<th>Test Boy</th><br />
<th>Test Girl</th><br />
<th>Total</th><br />
</tr><br />
<tr><br />
<th>Boy</th><br />
<th>50</th><br />
<th>0</th><br />
<th>50</th><br />
</tr><br />
<tr><br />
<th>Girl</th><br />
<th>25</th><br />
<th>25</th><br />
<th>50</th><br />
</tr><br />
</table></center><br />
<br />
Gigerenzer rightly concludes that the language of statistics is not natural for most individuals. Perhaps the puzzlement in this specific example is at least partly due to the natural language known as English. Boys, Girls, Test Boys and Test Girls are too confusing. . Replace "Boy" by "Norwegian" and "Girl" by "German" and assume that there are as many Norwegians as Germans. Let every Norwegian be "Blond," so that P(Blond| Norwegian) = 1 and only half the Germans are Blond. Thus, P(German| Not Blond) =1; the switch, P(German| Not Blond) = P(Blond| Norwegian) = 1, is rather obvious. Is the this situation easier to understand because of the linguistics--hair color and ethnicity are easily distinct as Test Boy and Boy are not?<br />
<br />
===DISCUSSION QUESTIONS===<br />
<br />
1. Gigerenzer has a chapter entitled, "(Un)Informed Consent." Based on your experience, what do you imagine the chapter contains?<br />
<br />
2. A drawing of two tables (that is, physical tables on which things are placed) appears on page 10. He claims the tables (due to Roger Shepard) are identical in size and shape. After staring at them in disbelief of the claim, how would you verify the contention?<br />
<br />
3. Physicians sometime make the following type of statement:"Never mind the statistics, I treat every patient as an individual." Defend this assertion. Criticize this assertion.<br />
<br />
4. The physicist, Lord Rutherford, is reputed to have said, " If your experiment, needs statistics you ought to have done a better experiment." Defend and criticize Lord Rutherford.<br />
<br />
5. Assume an asymptomatic woman has a mammogram which looks suspicious and then a biopsy which is negative. Would she be grateful for the clean bill of health or would she become an advocate who opposes (mass) screening? Suppose instead we assume a man has a suspiciously high PSA and the painful multiple biopsies (6-12 "sticks") are all negative. Would he be grateful for the clean bill of health or would he become an advocate who opposes (mass) screening? <br />
<br />
6. Calculated Risks also deals with the risk to the physician making a recommendation and a diagnosis. Discuss why in our present-day litigious society the risks to the physician (who may or may not recommend a test or may or may not make a diagnosis) are not symmetrical. Along these lines, who are the vested interests involved in maintaining screening and testing?<br />
<br />
7. Revisit the Boy/Girl scenario but now the test always says Boy regardless of gender, P(Test Boy| Boy) = P(Test Boy| Girl) = 1. Complete the table for this version. Obviously, this test has the advantage of being extremely simple, cost-free and non-invasive. Use either the Probability Format or the Frequency Format to comment on the statistical worthiness of this test.<br />
<br />
Submitted by Paul Alper<br />
<br />
==More medical studies the conflict with previous studies==<br />
<br />
[http://www.nytimes.com/2006/02/08/health/08fat.html?_r=1&oref=slogin Low-fat diet does not cut health risks, Study finds]<br><br />
''New York Times'', Feb. 8, 2006<br><br />
Gina Kolata<br />
<br />
[http://www.usatoday.com/news/health/2006-02-07-diet-fat-women_x.htm Cutting fat alone isn't enough, women advised]<br><br />
''USA TODAY'', Feb, 7, 2006<br><br />
Rita Rubin<br />
<br />
[http://www.post-gazette.com/pg/06040/652708.stm Popular herb shows no benefit for prostate]<br><br />
Wall street journal, Feb. 9, 2006<br><br />
Syllvia Pagan Westphal<br />
<br />
In the ''New York Times'' article we read:<br />
<br />
<blockquote>The largest study ever to ask whether a low-fat diet reduces the risk of getting cancer or heart disease has found that the diet has no effect.<br><br><br />
<br />
The $415 million federal study involved nearly 49,000 women ages 50 to 79 who were followed for eight years. In the end, those assigned to a low-fat diet had the same rates of breast cancer, colon cancer, heart attacks and strokes as those who ate whatever they pleased, researchers are reporting today.</blockquote><br />
<br />
In the ''Wall Street Journal'' article we read:<br />
<br />
<blockquote>Saw palmetto, an herbal supplement taken by 2.5 million Americans for problems with enlargement of the prostate gland, is no more effective than a placebo in alleviating the condition, according to a new study<br><br><br />
<br />
The perception that saw palmetto works had been supported by a number of clinical trials over the years. A comprehensive 2002 analysis of 21 trials involving over 3,000 men found that studies credited saw palmetto with providing "mild to moderate improvement in symptoms with fewer adverse events than finasteride (approved by the Food and Drug Administration to treat benign enlargement).</blockquote><br />
<br />
The saw palmetto study was reported in the ''New England Journal of Medicine'' February 9, 2006 and the low-fat diet study was reported in ''Jama'', February 8, 2006.<br />
<br />
The saw palmetto study had 225 participants randomized to give 112 saw palmetto and 113 placebo and the study lasted from July 2001 to May 2003.<br />
<br />
So once more the general public will wonder what the truth is. Commenting on the diet study Berkeley statistician David Freedmn is quoted as saying that the studies were well designed and should be taken seriously.<br />
<br />
Two of the 32 authors of the study, Judith Hsia, professor of medicine at George Washington University in Washington, D.C. and Ross Prentice, professor of biostatistics at the University of Washington in Seattle, were interviewed by Ira Flato on NPR's Talk of the Nation Friday Science program February 10, 2006. You can listen to them trying to do damage control [http://www.npr.org/templates/story/story.php?storyId=5200525 here] . The say that women should certainly not quit trying to control their diet. They point out that the study did not distinquish between "good" and "bad" fats. Prentice remarks that the incidence rate of breast cancer was 9% less in control group than in the placebo group. When Ira remarks that the study said that the difference was not significant, Prentice replied that you have to understand what statistical signficance meant and adds that if it were 10% it would have been signficant. <br />
<br />
The authors of the paper also comment that the study was not able to continue for the length of time originally planned and since the trend for the incidence of Breast cancer was in the right direction so it is possible that the difference might be significant over the longer time. Here is a graphic from the ''Jama'' article that shows the difference in the incident rates over time http://www.dartmouth.edu/~chance/chance_news/for_chance_news/wiki/diet.png.<br />
<br />
On Feb. 14 Kolata wrote in the ''Times'' a sequal [http://www.nytimes.com/2006/02/14/health/14fat.html Maybe you're not what you eat] to her Feb 8 article where she attempts to explain the conflicting views of the results of the Women's study. You will find [http://www.nytimes.com/2006/02/16/science/17askscience.html here] her answers to readers questions relating to her Feb. 14 article.<br />
<br />
Then in the Times on Feb. 16 she wrote an article [http://www.nytimes.com/2006/02/16/health/16bones.htm Big study finds no clear benefit of calcium pills] about another study based on the Women's study. She writes:<br />
<br />
<blockquote>The $18 million study was part of the Women's Health Initiative, a large federal project whose results have confounded some popular beliefs and raised questions about public health messages that had been addressed to the entire population.<br><br><br />
<br />
In the new study, the participants were randomly assigned to take 1,000 milligrams of calcium and 400 international units of vitamin D a day, or to take placebos, and were followed for seven years. Researchers looked for effects on bone density, fractures and colorectal cancer. The lack of an effect on colorectal cancer over the seven years was so clear that it has aroused little debate. But the effect on bones is another story.<br><br><br />
<br />
Osteoporosis specialists said the study, published today in the New England Journal of Medicine, was likely to put a dent in what has become a widespread medical practice of recommending that all women take calcium and vitamin D supplements starting at menopause if not sooner, as a sort of insurance policy against osteoporosis. But beyond that there is no agreement on what, if anything, healthy women should do.</blockquote><br />
<br />
This led to still another ''New York Times'' article by Denise Grady Feb. 19, 2006 <br />
[http://www.nytimes.com/2006/02/19/health/19health.html?ex=1140584400&en=9daef52512f69cfc&ei=507 Women's health sudies leaves questions in place of certainty] This article begins with:<br />
<br />
<blockquote>So what do women do now? The results of two major studies over the past two weeks have questioned the value of two widely recommended measures: calcium pills and vitamin D to prevent broken bones, and low-fat diets to ward off heart disease and breast and colon cancer.</blockquote><br />
<br />
The article discusses the conflicts between statisticians who are willing to accept the outcomes of the study and researchers who want to look at subgroups to try to argue that despite the lack of significance one can see hopeful signs. Statistician Susan Ellenberg remarks:<br />
<br />
The probability that you will see a spuriously positive effect gets very big very quickly.<br />
<br />
Ellenberg quotes another statistician, Richard Peto of Oxford University, who said of subgroups:<br />
<br />
<blockquote>You should always do them but you should never believe them.</blockquote><br />
<br />
You will also find in this article a nice graphic summerizing the results of the Women's study relating to low-fact diets and vitamin D.<br />
<br />
===Further reading===<br />
The low-fat diet study has attracted a lot of attention from bloggers.<br />
* [http://blog.proteinpower.com/drmike/archives/2006/02/man_bites_dog.html Man Bites Dog] and [http://blog.proteinpower.com/drmike/archives/2006/02/man_bites_dog_i.html Man Bites Dog II], Michael R. Eades, M.D. offers a critical review of the design of the study.<br />
* [http://www.weightoftheevidence.com/ Regina Wilshire's blog] on why we don't need more time and/or more studies to 'prove' that low-fat dieting really works.<br />
<br />
==A day in the life of a human rights statistician==<br />
[http://www.wired.com/news/technology/1,70196-0.html Coders Bare Invasion Death Count], By Ann Harrison, Wired News, 9-Feb-06.<br><br />
[http://www.boingboing.net/2006/02/11/how_statistics_caugh.html How statistics caught Indonesia's war-criminals ], Cory Doctorow, BoingBoing.net<br />
<br />
A group of determined programmers and statisticians,<br />
the [http://www.hrdag.org/about/ Human Rights Data Analysis Group], released a [http://www.hrdag.org/resources/timor_chapter_graphs/timor_chapter_page_01.shtml report] documenting over civilian deaths in the former Portuguese colony, which occurred from a year prior to the Indonesian army's invasion in 1975, to the country's 1999 independence referendum that formally ended the occupation.<br />
[http://www.hrdag.org/about/timor-leste.shtml Statistical analysis] establishes that at least 102,800 (+/- 11,000) Timorese died as a result of the conflict. Approximately 18,600 (+/- 1000) Timorese were killed or disappeared, while the remainder died due to hunger and illness in excess of what would be expected due to peacetime mortality. <br />
<br />
Group director Patrick Ball says <br />
<blockquote><br />
By having an accurate statistical picture of the suffering, we can draw conclusions about what the causes of the violence might have been and identify likely perpetrators with a claim based on thousands of witnesses.<br />
</blockquote><br />
<br />
The group established three datasets that integrated quantitative methods into broader truth seeking activities. These datasets included:<br />
* The commission's statement-taking process, which collected almost 8,000 narrative testimonies from people in every sub-district; <br />
* A census of all public graveyards in the country (encompassing approximately 319,000 gravestones); <br />
* A retrospective mortality survey drawing on a probability sample of approximately 1,400 households throughout the thirteen districts of Timor-Leste. <br />
In establishing these data, HRDAG and the Commission for Reception, Truth and Reconciliation in East Timor (CAVR) pioneered a number of new techniques and methods. <br />
No other truth commission has ever undertaken a retrospective mortality survey. <br />
While gravestone information for mortality estimation has been used by historical demographers for mortality estimations, this is the first time that a human rights project has employed such methods. <br />
These projects were so large that HRDAG developed automated techniques to link multiple reports of the same death - a key component of [http://www.hrdag.org/resources/mult_systems_est.shtml multiple systems estimation],<br />
a technique that uses two separately collected but incomplete lists of a population to estimate the total population size.<br />
<br />
HRDAG uses the multiple systems estimation technique in human rights cases to project the total number of violations, including those that were never documented. This information is vital to producing a complete accurate historical record of the violations and to provide evidence at the trial of the architects of large-scale human rights abuses.<br />
In order to make statistical inferences from multiple systems estimation, it is necessary to:<br />
* Identify overlapping reports <br />
* Control for bias and variation in coverage rates <br />
* Estimate the total magnitude <br />
<br />
Ball has spent the last 15 years building systems and conducting qualitative analysis for large-scale human rights data projects around the world.<br />
HRGAD researchers used comparative analysis of the datasets to uncover patterns of deaths and build objective evidence of abuses. The team also developed an array of descriptive statistical analysis profiling the scale, pattern and structure of torture, ill-treatment, arbitrary detention and sexual violations. <br />
In order to estimate what was missing from the data, the HRDAG developed software to link multiple reports of the same death in a technique called record linkage. <br />
They then used multiple systems estimation to calculate the number of deaths that no one remembered. <br />
<br />
Romesh Silva, a HRDAG field statistician who led the design and implementation of the project's data, says<br />
<blockquote><br />
The Indonesian military has persistently argued that excess mortality in Timor due to its occupation of Timor was zero.<br />
This claim can now be tested empirically and transparently with the tools of science instead of merely being debated with the tools of political rhetoric.<br />
</blockquote><br />
<br />
The final report of the CAVR was handed over to the President of Timor-Leste on 31 October 2005. The President of Timor-Leste then tabled the report at a special sitting of Timor-Leste's National Parliament on 28 November, 2005 - which coincided with the 30th anniversary celebrations of Timor's Proclamation of Independence. <br />
<br />
===Further reading===<br />
* [http://www.hrdag.org/about/ The Human Rights Data Analysis Group (HRDAG)] develops information technology solutions and statistical techniques to help human rights advocates build evidence-based arguments.] See the [http://www.hrdag.org/about/faqs.shtml FAQ] for more info.<br />
* [http://www.hrdag.org/resources/timor_chapter_graphs/timor_chapter_page_01.shtml The Profile of Human Rights Violations in Timor-Leste, 1974-1999.] A Report by the Benetech Human Rights Data Analysis Group to the Commission on Reception, Truth and Reconciliation of Timor-Leste. 9 February 2006.<br />
* [http://www.hrdag.org/about/romesh_silva.shtml Romesh Silva] and [http://www.hrdag.org/about/patrick_ball.shtml Patrick Ball] designed and conducted the statistical analysis and wrote this report. Their on-line profiles provide more information about their statistical work and the awards that they have received. The are also profiles of other [http://www.hrdag.org/about/people.shtml statistical consultants] at HRDAG.<br />
Two short papers by Romesh and Ball are worth reading:<br />
* [http://paa2006.princeton.edu/download.aspx?submissionId=60827 The Demography of Large-Scale Human Rights Atrocities: Integrating demographic and statistical analysis into post-conflict historical clarification in Timor-Leste.] Romesh Silva and Patrick Ball. A 5-page paper presented at the 2006 meetings of the Population Association of America.<br />
* [http://www.austms.org.au/Publ/Gazette/2005/May05/careersilva.pdf My brilliant career - Quantitative Data Analysis and Large-Scale Human Rights Violations: An Example of Applied Statistics at the Grassroots.] Romesh Silva. Gazette of the Australian Mathematical Society. Canberra (Australia). Volume 32, Number 2, May 2005. A 5-page paper on where a mathematics education can lead you. <br />
** "in the late 1990’s as I was completing my honors degree in statistics at UNSW, I became increasingly involved with Amnesty International ... I began to wonder how I might be able to directly apply my mathematical education and quantitative skills to international human rights. ... As the field of human rights statistics is relatively new, our main challenge remains in attracting more mathematicians and statisticians to work in this area and also communicating to the human rights field how quantitative data analysis can contribute to accountability and truthtelling processes."<br />
<br />
Submitted by John Gavin.<br />
<br />
==Another record jackpot for the Powerball lottery==<br />
[http://www.startribune.com/535/story/247617.html Elusiveness of Powerball is revealed in the math]<br><br />
Minneapolis Star Tribune, Feb. 15, 2006<br><br />
Mike Meyers<br />
<br />
[http://www.latimes.com/news/columnists/la-oe-daum25feb25,1,5399378.column?coll=la-news-columns&ctrack=1&cset=true Whose the idiot now?]<br><br />
''Los Angeles Times'', Feb. 25, 2006<br><br />
Meghan Doum.<br />
<br />
When a powerball jackpot nears a new record the media asks experts to comment on what the odds are and to explain how unlikely you are to win a lottery. See [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_8#A_record_powerball_lottery_jackpot Chance News 8] for interesting comments of two Minnesota mathematicians related to the October 22, 2005 record $340 million powerball jackpot. For his article related to the current record $365 jackpot, Meyers consulted [http://www.math.temple.edu/~paulos/ John Paulos] author of the bestselling book, "Innumeracy" and a monthly column [http://abcnews.go.com/Technology/WhosCounting/story?id=1560771 Who's Counting] for ABCNews.com. <br />
<br />
We read:<br />
<br />
<blockquote> Paulos says lotteries have always owed their appeal to people's loose grip of math and recalled a line from Voltaire: "Lotteries are a tax on stupidity."<br><br><br />
<br />
Paulos once tore up a Powerball ticket on the eve of a drawing in front of an audience. "They all gasped as if I just slashed the Mona Lisa," he said. </blockquote><br />
<br />
While the Voltaire quote is on many websites and usually attributed to Voltaire our librarians were unable to find it's source. Perhaps a reader can provide this. However in our search we did find a similar quotation:<br />
<br />
<center>A lottery is a taxation, Upon all the fools in Creation;<br><br />
And Heav'n be prais'd, It is easily rais'd, <br><br />
Credulity's always in fashion; <br><br />
For, folly's a fund, Will never lose ground,<br><br />
While fools are so rife in the Nation.</center><br />
<div align="right">Henry Fiellding 1707-54<br><br />
</div><br />
<br />
From Wikipedia we read:<br />
<br />
<blockquote>'''Henry Fielding''' was an English novelist and dramatist known for his rich earthy humor and satirical prowess and as the author of the novel ''Tom Jones''.</blockquote><br />
<br />
The quotation comes from Fielding's play [http://www.ebookmall.com/ebook/169052-ebook.htm ''The Lottery, a farce''] (1724)<br />
<br />
In her ''Los Angelas Times'' article [http://www.latimes.com/news/columnists/la-oe-daum25feb25,1,5399378.column?coll=la-news-columns&ctrack=1&cset=true"Who's the idiot now?] about the winners of the current record lottery columnest Meghan Daum writes:<br />
<blockquote>On Wednesday morning in Lincoln, Neb., after four days of speculation about who had won the biggest jackpot in Powerball history, eight employees of a ConAgra ham processing plant came forward and identified themselves as the winners of the $365-million purse. As lottery stories go, this is about as heartwarming as it gets. Two of the winners are immigrants from Vietnam and one is a political refugee from the Republic of Congo -- and all worked the second and third shifts, some clocking as many as 70 hours a week. There is probably no jobsite as gruesome as a meatpacking house. If anyone deserves an express ticket to a new life, it's these folks. </blockquote><br />
<br />
Equally moving is to listen [http://www.latimes.com/news/columnists/la-oe-daum25feb25,1,5399378.column?coll=la-news-columns&ctrack=1&cset=true here] to the winners answers in an interview by Sara McCammon on NPR ''All things considered'' Feb. 22, 2006.<br />
<br />
==Europe's statisticians are too gloomy==<br />
[http://www.economist.com/finance/displayStory.cfm?story_id=5531335 A numbers racket], The Economist, 18-Feb-06.<br><br />
[http://www.economist.com/displaystory.cfm?story_id=E1_VVDQTDP How to measure economies], The Economist, 9-Feb-2006 (subscription required).<br />
<br />
The first article highlights how statistical biases can influence perceptions of economic growth.<br />
The second gives more information about the merits of [http://en.wikipedia.org/wiki/Gross_domestic_product gross domestic product (GDP)] relative to other economic indicators.<br />
<br />
GDP per head is the most commonly used measure of a country's success. <br />
It was primarily developed as a planning tool to measure productivity during World War II<br />
as it measures value of goods and services produced by the residents of a country.<br />
A nation's well-being depends on factors not covered by GDP, such as leisure time, income inequality and the quality of the envirnoment but GDP was never intended to measure welfare.<br />
For most purposes, it the best available indicator on a timely basis so governments worry about how to boost their GDP growth.<br />
<br />
There is a wide gap between America's and Europe's GPD per head.<br />
Since the start of [http://en.wikipedia.org/wiki/European_Monetary_Union European Monetary Union] in 1999, revisions to [http://en.wikipedia.org/wiki/Gross_domestic_product gross domestic product (GDP)] growth have almost always been upwards. In contrast, revisions in America have tended to be downwards. The initial figures which grab newspaper headlines therefore exaggerate Europe's economic underperformance. <br />
<br />
The Economist resists the obvious conclusion:<br />
<blockquote><br />
Discounting the obvious explanation that American statisticians are born optimists, it is unclear what lies behind the consistent direction of these revisions. <br />
</blockquote><br />
<br />
This article is based on a paper by Kevin Daly, an economist at Goldman Sachs.<br />
He calculates that, based on the GDP-growth figures first published in each quarter, the euro area would have grown by an annual average of only 1.6% in the six years to 2004. Yet the latest figures put the growth rate at 2.0%. <br />
In contrast, the first published figures gave America an average growth rate of 3.1%; but that has now been shaved down to 2.8%. The revisions have cut the reported gap between growth rates in America and the euro area in half. As a result, the euro area's GDP per head has in fact grown at the same pace as America's. <br />
<br />
The Economist goes on to comment:<br />
<blockquote><br />
Europe could rejoice in further upward revisions to growth if its governments were to adopt American statistical practices. Price deflators there take more account of improvements in the quality of goods, such as computers, and thus a given rise in nominal spending implies faster growth in real terms. By using higher inflation rates, the euro area understates its growth relative to America's. In addition, American statisticians consider firms' spending on software that is written in-house to be investment, while in the euro area it is often counted as an expense and so is excluded from final output. The surge in software spending has therefore inflated America's relative growth. <br />
<br><br />
<br><br />
On past experience, Europe's statisticians should add half a percentage point to their first guesses of GDP growth. By also switching to American practices, they could boost growth even further. Instead, their cautious ways are making Europe's economies look more dismal than they are, and gloomy headlines are discouraging consumers from spending. Perhaps Europe should outsource the compilation of its statistics to America, and then watch the boom.<br />
</blockquote><br />
<br />
The second Economist article says that the OECD is encouraging governments to move from relying <br />
on just one indicator. Alternatives, like [http://en.wikipedia.org/wiki/Gross_national_income gross] or net national income suggest that the gap between American and European growth rates may much smaller.<br />
<br />
===Further reading===<br />
[http://www.sbe.co.uk/pdfs/articles/34_3_Daly.pdf Has Euroland Performed That Badly?], Kevin Daly, Golman Sachs. Daly says <br />
<blockquote><br />
Euroland productivity when measured appropriately is not only close to US levels but, over the past ten years as a whole, its growth has continued to surpass that of the US. The<br />
US’s superior GDP performance over this period has not been attributable to faster productivity growth but to a more rapidly expanding labour force that is prepared to work longer hours.<br />
</blockquote><br />
<br />
Submitted by John Gavin.<br />
<br />
==Single and not so carefree==<br />
<br />
Premature mortality among lone fathers and childless men. Ringback Weitoft G, Burstrom B, Rosen M. Soc Sci Med. 2004 Oct;59(7):1449-59.<br />
<br />
This study is a couple of years old, but it is interesting in itself and in how it was reported by a conservative advocacy group. I have not read the full article, so I can only comment on the abstract, which is [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15246173&dopt=Citation available on PubMed].<br />
<br />
These researchers studied 682,919 men and divided them into five groups (lone fathers with custody of their child/children, lone fathers without custody, childless men with a wife, childless men without a wife, and men with a wife and men with a wife and child/children. The last group was the comparison group for all comparisons. They analyzed deaths in these groups from 1991 to 2000.<br />
<br />
<blockquote>"The results suggest that lone non-custodial fathers and lone childless men face the greatest increase in risks, especially from injury and addiction, and also from all-cause mortality and ischaemic heart disease. Being a lone custodial father also entails increased risk, although generally to a much lesser extent, and not for all outcomes. The elevated risks found in all the subgroups considered diminished substantially when proxy variables to control for health-selection effects and socioeconomic circumstances were added to the initial model. Risks fell most in response to introduction of the socioeconomic variables, but health selection also played a major role, mostly in the cases of lone non-custodial fathers and lone childless men. However, even following these adjustments, significant risk increases, although greatly attenuated, remained for all the subgroups."</blockquote><br />
<br />
No mention was made about adjustment for age, but this would have to be done because there is almost certainly a large disparity in the age of men with and without children.<br />
<br />
I became aware of this paper when my brother-in-law sent me an email describing the study that was produced by [http://www.profam.org/Default.htm The Howard Center for Family, Religion, & Society]. This group is located in Rockford, Illinois and does not seem to be associated with Howard University. This group advocates for many conservative family values causes, and opposes gay marriage and no fault divorce. They regularly summarize research studies that support their political viewpoint. There are many other organizations, of course, that advocate viewpoints of all types and they also summarize studies that favor their political outlook.<br />
<br />
There was a large discrepancy, however, in the information provided in the abstract and the information provided by this website. In particular, the website lists actual numbers from the publication itself while the abstract did not report any quantitative results.<br />
<br />
<blockquote>Sharp differences in mortality rates separated these five groups, with men living alone, apart from their children, at greatest risk of premature death. In comparison with men living with a wife (or partner) and their children, fathers living alone—without spouse (or partner) and apart from their children—experienced “almost 4 times as great a risk of all-cause mortality, 10 times of death from external violence, 13 times from fall and poisoning, almost 5 times from suicide, and 19 times from addiction.”</blockquote><br />
<br />
You can read [http://www.profam.org/pub/nr/nr_1811.htm#Men_Dying_Alone the full summary] which does mention the attenuation of these effects after statistical adjustments, but does not report the adjusted rates, only the unadjusted ratios.<br />
<br />
===Questions===<br />
<br />
1. What do you think the "proxy variables to control for health-selection effects and socioeconomic circumstances" are?<br />
<br />
2. Why is it important to adjust for these variables and why are proxies needed?<br />
<br />
3. List some covariates which could possibly be imbalanced between the five groups studied other than health selection effects, socioeconomic circumstances, and presumably age. Could any of these influence mortality results?<br />
<br />
4. Why would a reviewer be interested in the unadjusted ratios rather than the adjusted ratios?<br />
<br />
5. Do you feel that the Howard Center for Family, Religion, & Society summary is a fair and balanced representation of the work by Ringback Weitoft et al? Be sure to read [http://www.profam.org/pub/nr/nr_1811.htm#Men_Dying_Alone the full summary] rather than my extract, because my summary of their summary could be biased.<br />
<br />
6. Should the original authors have included more quantitative results in their abstract?<br />
<br />
Submitted by Steve Simon</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_12&diff=1962Chance News 122006-01-23T20:35:00Z<p>Thekohser: /* Superflous Medical Studies */</p>
<hr />
<div>==Screening==<br />
<br />
Screening<br />
<br />
<blockquote>''From the doctors' perspective, early detection has other appealing features: ordering a test is quick and easy, and it has an established billing process--unlike health promotion counseling''.<br><br />
--H. Gilbert Welch</blockquote><br />
<br />
For a related story, see [[Chance_News_8#Mammograms_Validated_as_Key_in_Cancer_Fight | this page.]]<br />
<br />
One thing almost all people know is that it is prudent to be screened for diseases because that will add to their longevity. However, according to H. Gilbert Welch, a medical doctor at Dartmouth College, it isn't necessarily so.<br />
<br />
His book, ''Should I Be Tested For Cancer? Maybe Not And Here's Why'' [University of California Press, 2004], focuses on screening which is a particular form of testing and he deals exclusively with cancer as opposed to other afflictions. Screening "means the systematic examination of asymptomatic people to detect and treat disease." His contention is that screening for cancer is inefficient in that very few people who actually have the particular cancer are both discovered and then cured. Moreover, the false positives result in many problems of which the general public is not aware. On the other hand, false negatives of cancer screening are barely mentioned in his book "because we do not biopsy people with negative screening tests." That is, we can't distinguish between a false negative and a rapidly-growing cancer that emerges in between screenings.<br />
<br />
In a nutshell, randomized clinical screening trials for those cancers discussed in the book--lung cancer, cervical cancer, breast cancer, prostate cancer and colon cancer-- have statistically shown that screening has provided very little benefit in terms of mortality. Welch argues that with the new, exquisite devices such as CAT scans, MRIs, etc., now available, it is possible to detect cancer earlier so that it seems that the 5-year survival rates have improved; victims are living longer not because the treatments are better but only because the diagnoses were made earlier. Further, these devices are detecting what he calls "pseudodiseases," cancers which will never develop into a cancer that will cause a problem. It follows that this detection of cancers which would never have been discovered years ago when there was a lack of technology, further inflates the 5-year survival rate, a figure of merit which he would like to see abolished because it is so misleading.<br />
<br />
He argues that the side effects of a false positive are not to be taken lightly. Chapters 2 and 3 are entitled "You may have a cancer 'scare' and face an endless cycle of testing" and "You may receive unnecessary treatment," respectively. Certainly, in bygone days being told that you had cancer was frightening in the extreme. Perhaps not so much in these enlightened times, but a stay in a hospital, especially for an unnecessary procedure, can definitely lead to unpleasant side effects such as infection or worse. <br />
<br />
Welch points out that there are vested interests in the screening industry: doctors, hospitals, clinics, insurance companies and lay organizations which depend for their existence, financial and otherwise, on keeping Americans fully screened and uninformed about the problems connected with screening. For example, although it has been statistically shown via randomized clinical screening trials that mammography, an unpleasant procedure at best, is not useful for women under 50, the "mammography lobby," made up of manufacturers, radiologists, ideologues and feminists who considered the studies to be a male plot, went ballistic and wanted to substitute emotion for science: The National Cancer Institute reconsidered and by 17 to 1 decided "in favor of recommending mammography to all women in their 40s."<br />
<br />
The same sort of situation applies to prostate cancer. The accepted, conventional wisdom in the United States is that screening must be worthwhile because it is self-evident even though a careful look at the data points in the opposite direction. Watchful waiting, a much used medical treatment in Europe for prostate cancer is frequently ridiculed in this country by both laymen and urologists.<br />
<br />
Welch fully realizes his thesis--screening for most cancers is, by and large, ineffective and/or harmful--will not go over well because it "flies in the face of medical dogma." His "book is not about what to do if you know you have cancer; it is about informing the decision of whether to look for cancer when you are well." This distinction has been lost on the people I have spoken to. The conventional wisdom that cancer screening must be desirable is a notion that, as far as I can tell from my experience when discussing it with others, is unchallengeable. To be even more cynical, any doctor who doesn't order a screening test for a patient who eventually gets cancer is likely to be sued successfully, so ingrained is the conventional wisdom among the general public and judges alike.<br />
<br />
Submitted by Paul Alper<br />
<br />
==Is the human brain a Bayesian-reasoning machine?==<br />
[http://economist.com/science/displaystory.cfm?story_id=5354696&no_na_tran=1 Bayes rules], Jan 5th 2006, The Economist.<br><br />
<br />
The lead article in this weeks Science & Technology section of The Economist claims that Bayesian statistics may help to explain how the mind works and even argues that the human mind is a Bayesian one.<br />
<br />
The Economist article begins with a summary of Bayes' ideas:<br />
<blockquote><br />
[[http://en.wikipedia.org/wiki/Bayes Bayes] ideas] about the prediction of future events from one or two examples were popular for a while, and have never been fundamentally challenged. But they were eventually overwhelmed by those of the [http://en.wikipedia.org/wiki/Frequentist frequentist] school, which developed the methods based on sampling from a large population that now dominate the field and are used to predict things as diverse as the outcomes of elections and preferences for chocolate bars.<br />
</blockquote><br />
<br />
But, Bayes has recently started a comeback, among computer scientists designing software with human-like intelligence, such as internet search engines and automated 'help wizards'.<br />
In many situations, the true answer cannot be determined based on the limited data available, <br />
yet common sense suggests at least a reasonable guess.<br />
For example, <br />
* how much longer will a 60-year old man live?<br />
* can you identify a three-dimensional object from a two-dimensional diagram?<br />
* what is the total gross from a movie that has made $40m at the box-office, so far?<br />
That has prompted some psychologists to ask if the human brain itself might be a Bayesian-reasoning machine.<br />
Accounts of human perception and memory suggest that these systems effectively<br />
approximate optimal statistical inference, correctly combining new data with an accurate<br />
probabilistic model of the environment.<br />
The Economist article suggests that<br />
<blockquote><br />
The Bayesian capacity to draw strong inferences from sparse data could be crucial to the way the mind perceives the world, plans actions, comprehends and learns language, reasons from correlation to causation, and even understands the goals and beliefs of other minds.<br />
</blockquote><br />
<br />
It goes on to summarises how Bayesian reasoning works <br />
<blockquote><br />
The key to successful Bayesian reasoning is not in having an extensive, unbiased sample, which is the eternal worry of frequentists, but rather in having an appropriate “prior”, as it is known to the cognoscenti. This prior is an assumption about the way the world works-in essence, a hypothesis about reality-that can be expressed as a mathematical probability distribution of the frequency with which events of a particular magnitude happen.<br />
</blockquote><br />
It claims that frequentism is thus a more robust approach but it is not well suited to making decisions on the basis of limited information - which is something that people have to do all the time - and this is where Bayesian statistics excels.<br />
<br />
The article discusses four prior distributions: Gaussian, Poisson, [http://en.wikipedia.org/wiki/Erlang_distribution Erlang] and [http://en.wikipedia.org/wiki/Power_law power-law]<br />
and [http://web.mit.edu/cocosci/Papers/prediction10.pdf an experiement] that the scientists,<br />
Thomas Griffiths at Brown and Joshua Tenenbaum at MIT, conducted by giving <br />
individual nuggets of information to each of the participants in their study <br />
and asking them to draw a general conclusion. <br />
<br />
The experiment found that people could make accurate predictions about the duration or extent of everyday phenomena,<br />
given limited data, such as:<br />
(The authors used publicly available data to identify the true prior distributions shown in brackets.)<br />
* estimate what its total box-office “gross” takings of a movie, even though they were not told for how long it had been on release so far (power-law)<br />
* the number of lines in a poem, given how far into the poem a single line is (power-law)<br />
* the time it takes to bake a cake, given how long it has already been in the oven (a complex and irregular distribution, according to the authors)<br />
* the total length of the term that would be served by an American congressman, given how long he has already been in the House of Representatives (Erlang)<br />
* an individual's lifespan given his current age (approx Gaussian) <br />
* the run-time of a film (approx Gaussian)<br />
* the amount of time spent on hold in a telephone queuing system (traditionally a Poisson but the experiment's results suggests a power-law distribution which matches other recent research)<br />
* reigns of Pharaohs (approx Erlang)<br />
<br />
Accounts of human perception and memory suggest that these systems effectively<br />
approximate optimal statistical inference, correctly combining new data with an accurate<br />
probabilistic model of the environment.<br />
People’s prediction functions took on very different shapes in domains characterized by <br />
Gaussian, power-law, or Erlang priors, just as expected under the ideal Bayesian analysis.<br />
<br />
There were exceptions, such as an inability of the human brain to estimate the length of the reign of an Egyptian Pharaoh in the fourth millennium BC. <br />
People consistently overestimated this.<br />
The analysis showed that the prior they were applying was an Erlang distribution, which was the correct type. <br />
They just got the parameters wrong, <br />
presumably through lack of knowledge of political and medical conditions in fourth-millennium BC Egypt.<br />
<br />
The authors claim that <br />
<blockquote><br />
everyday cognitive judgments follow the same optimal statistical principles as perception and memory <br />
[which are often explained as optimal statistical inferences, informed by accurate prior probabilities],<br />
and reveal a close correspondence between people’s implicit probabilistic<br />
models and the statistics of the world.<br />
</blockquote><br />
<br />
How the priors are themselves constructed in the mind has yet to be investigated in detail. <br />
Obviously they are learned by experience, but the exact process is not properly understood. <br />
The Economist article finishes with a cautionary note for both Bayesians and frequentists<br />
<blockquote><br />
Things dont always go smoothly with a Bayesian approach.<br />
Sometimes the process goes further and further off-track and the authors speculate <br />
that that might explain the emergence of superstitious behaviour, with an accidental correlation or two being misinterpreted by the brain as causal. A frequentist way of doing things would reduce the risk of that happening. But by the time the frequentist had enough data to draw a conclusion, he might already be dead.<br />
</blockquote><br />
<br />
===Further reading===<br />
* [http://economist.com/science/displaystory.cfm?story_id=5354696&no_na_tran=1 Bayes rules], Jan 5th 2006, The Economist. - the full article is worth reading.<br />
* [http://web.mit.edu/cocosci/Papers/prediction10.pdf Optimal predictions in everyday cognition], Thomas L. Griffths, Department of Cognitive and Linguistic Sciences, Brown University & Joshua B. Tenenbaum, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology. <br />
** The paper shows the emprical distributions for the each of the variables being estimated along with more details about the experiment.<br />
<br />
Submitted by John Gavin.<br />
<br />
==Superfluous Medical Studies==<br />
Superfluous Medical Studies<br><br />
''When a patient volunteers for a randomized clinical trial, he or she strikes an implicit bargain with the researcher. The patient may benefit, but even if he does not, others will. That is because the study will produce new knowledge. But if the question is already settled, then the patient's sacrifice and altruism are for naught.''<br><br />
Steven N. Goodman, Johns Hopkins University biostatistician<br />
<br />
Clinical trials have been the bread and butter for many a statistician. A frequent tagline to such studies is, "More research needs to be done" which implies further employment for statisticians. If the results are overall underwhelming, perhaps the procedure/medication works better on women, or Hispanics, or the elderly or some other subgroup and so the studies proliferate. David Brown's article in the ''Washington Post'' of January 2, 2006 looks at several instances where, on the contrary, the evidence is so convincing that no more studies need or should be done. As he puts it, "What part of 'yes' don't doctors understand." Specifically, he cites the use of aprotinin in heart surgery, SIDS (sudden infant death syndrome) prevention and the use of streptokinase to treat heart attacks.<br />
<br />
According to Brown, there have been 64 studies of aprotinin since 1987 but by the 12th in 1992 it was clear that aprotinin reduced bleeding. "On average, each new paper listed only one-fifth of the previous studies in its references." Although "Being given a placebo long after aprotinin's value had been proved probably did not cost lives, the same cannot be said of medicine's failure to pay attention to studies of infant sleep position."<br />
<br />
A child health expert alleges that "if researchers had pooled the results of the oldest studies [40 studies back to 1965] and analyzed them, they might have gotten a big hint by 1970 that putting babies to sleep on their stomachs raised the risk of SIDS" sevenfold. By the 1990s,"at least 50,000 excess [SIDS] deaths were attributable to harmful health advice." <br />
With regard to streptokinase, it lowered death rates by 25%; "that conclusion and the percentage, did not budge while 34,542 more patients were enrolled in 25 more trials of streptokinase over the next 15 years" from 1973 to 1988.<br />
<br />
In order to rectify this excessive zeal on the part of researchers, "The Lancet, a British journal, announced last summer that it will require that authors submitting papers show they performed a meta-analysis of previous research or consulted an existing one." Goodman claims that "In 10 years we are going to look back on this time, and we won't believe this wasn't done as a matter of course."<br />
<br />
Submitted by Paul Alper<br />
<br />
==Are We Descended from Cannibals?==<br />
Are We Descended from Cannibals? Micheal Balter, ScienceNOW Daily News,<br />
6 January 2006. <br><br />
<br />
A study published 2 years ago in [http://www.sciencemag.org/cgi/content/abstract/300/5619/640 Science (25 April 2003, p. 640)], led by John Collinge of University College London (UCL), <br />
claimed that modern humans harbor a gene that allowed our ancestors to engage in cannibalism.<br />
The gene, called PRNP, codes for [http://en.wikipedia.org/wiki/Prions prions,]<br />
thought to be responsible for several neurodegenerative diseases, <br />
including Creutzfeldt-Jacob Disease (CJD) and kuru.<br />
Individuals with certain variations in this gene are more resistant to those diseases.<br />
<br />
The claim was based on a sample of 1,000 people from populations around the world<br />
and suggested that variations on this gene had survived for 500,000 years.<br />
The researchers hypothesized that the gene survived due to widespread cannibalistic practices that had made early humans susceptible to prion diseases.<br />
<br />
But a recent second paper in <emGenome Research</em>,<br />
by Jaume Bertranpetit and his coworkers at the Pompeu Fabra University in Barcelona,<br />
contradicts this result.<br />
It rejects the model of selection and claimed that the Science paper<br />
was statistically skewed because its study <br />
ignored low frequency variations of the gene, an error known as [http://en.wikipedia.org/wiki/Ascertainment_bias ascertainment bias.]<br />
This second paper used a sample of 174 people from around the world.<br />
<br />
Lead author of the Science paper, Simon Mead of UCL, stands by his original claim and argues that his paper's conclusions were based on several different lines of evidence that trump criticisms of ascertainment bias.<br />
<br />
===Questions===<br />
* Is a sample size of 1,000 people sufficient to extrapotate to the world population over the last 500,000 years?<br />
* Is the much smaller sample size of 174 in the second paper justifiable? <br />
<br />
===Further reading===<br />
Incidently, the wikipedia link above to [http://en.wikipedia.org/wiki/Prions prions] warns '[http://en.wikipedia.org/wiki/Wikipedia:External_peer_review/Nature_December_2005/Errors#Prion This article] has been identified as possibly containing errors', referring to [http://en.wikipedia.org/wiki/Wikipedia:External_peer_review/Nature_December_2005/Errors a study in the journal Nature] comparing Wikipedia to Britanica. This comparison was the subject of [http://chance.dartmouth.edu/chancewiki/index.php/Chance_News_10#Wikipedia_and_Britannica_go_head_to_head a previous Chance news item].<br />
<br />
Submitted by John Gavin.<br />
<br />
==Data Mining 101: Finding Subversives with Amazon Wishlists==<br />
[http://www.applefritter.com/bannedbooks Data Mining 101: Finding Subversives with Amazon Wishlists], Tom Owad. applefritter.com, January 4, 2006.<br />
<br />
This article explains a novel source for data mining, <br />
the information contained in the popular Amazon wishlists,<br />
and discusses the political implications of its use.<br />
It is not written from a statistical point of view but <br />
it offers an interesting case study in data-mining and exploratory data analysis (EDA).<br />
<br />
The author uses readily-available open-source software to access over 260,000 wishlists from U.S. citizens.<br />
He says<br />
<blockquote><br />
All the tools used in this project are standard and free. The services, likewise, are all free. The technical skills required to implement this project are well within the abilities of anybody who has done any programming.<br />
</blockquote><br />
<br />
Owad suggests that based on this information, it is possible to compile a list<br />
of people who expressed an interest in certain books.<br />
The author offers a sample of the list he compiled<br />
and invites everyone to make up their own list and explore the data. <br />
As an example he asks <br />
<blockquote><br />
What books are most dangerous?<br />
Send it to the FBI. I'm sure they'll appreciate your help in fighting terrorism.<br />
</blockquote><br />
Owad offers some examples of 'subversive' authors, such as Michael Moore (the fringe left) or Rush Limbaugh (the fringe right).<br />
<br />
As part of his EDA, he impressively converted City and state information on each person to latitude and longitude coordinates,<br />
using the free on-line [http://www.ontok.com/ Ontok Geocoder] service<br />
and then mapped those locations using Google's [http://www.google.com/apis/maps/ Maps API].<br />
For example, you could see the locations of all people who expressed an interest in a certain book<br />
and live in a certain city or even a certain street.<br />
<br />
==Further reading==<br />
There are many comments on this article posted on the same webpage.<br />
<br />
Submitted by John Gavin.</div>Thekohserhttps://www.causeweb.org/wiki/chance/index.php?title=Chance_News_11&diff=1921Chance News 112006-01-03T21:37:05Z<p>Thekohser: /* Investing in a poker player */</p>
<hr />
<div>==Quotation==<br />
<blockquote> "Then there was the man who drowned crossing a stream with an average depth of six inches." - W.I.E. Gates<br />
</blockquote><br />
<br />
==Forsooth==<br />
Here is a Forsooth from the December 2005 issue of RSS News.<br />
<blockquote> The current rate of shrinkage they calculate at 8% per decade; at this rate there may be no ice at all during the summer of 2060 </blockquote><br />
<br />
<div align="right">[http://news.bbc.co.uk/1/hi/sci/tech/4290340.stm BBC News website]</div><br />
<br />
==Investing in a poker player==<br />
<br />
Texas Hold'em poker is sweeping the globe as a favorite pastime of gamblers, young and old, novices and experts. <br />
<br />
The following web site discusses a proposition from an amateur poker player to gain financial backing for entry into the 2006 World Series of Poker. <br />
<br />
[http://www.pledgebank.com/investmentpoker Pledgebank: Investment poker]<br />
<br />
<blockquote><br />
The 2006 WSOP will likely have at least 8,000 participants, each ponying up $10,000 for the buy-in. The winner could take home $10 million. I will take vacation time and travel to Las Vegas to participate in this event, using $1,000 of my own money to complete the buy-in with nine other sponsors. <br />
<p></p><br />
Any cash winnings garnered from the tournament will be split twelve ways. Each of the nine outside sponsors will receive a 1/12th cut, I will receive a 1/6th cut, since I am taking vacation time and paying for travel and lodging. A final l/12th of the winnings will be donated to a non-profit charity voted on by the nine outside sponsors, to be assessed equally from the nine sponsors as a tax write-off.<br />
<p></p><br />
I am an experienced and successful online multi-table tournament player (my cashes are currently 155% of my buy-ins for the year), and I also have in-person tournament experience in Atlantic City. I recently came in first place in an online tournament against 450 players: [http://www.pokerroom.com/account/profile/?id=31a39c&main=pokah Link to Pokah! page]. This alone should demonstrate my potential for finishing in the money at the WSOP. (The top 10% are paid.) <br />
<p></p><br />
Once I have nine sponsors, I will have an attorney draw up a binding financial contract. If for any reason I cannot attend the WSOP, all contributions will be returned to investors.<br />
</blockquote><br />
<br />
The notion of players receiving outside backing in a big-stakes tournament is not new. Most recently, though, the 2nd-place finisher in the 2005 WSOP had a 50-50 deal with one financial angel investor. Steve Dannenmann has a bachelor’s degree from the University of Baltimore and was a CPA and mortgage banker before winning $4,250,000 in the WSOP, his first ever.<br />
<br />
A friend of Dannenman's, Jerry Ditzell, split the $10,000 entry fee with him -- each put up half of the money. After Dannenman won, they went to the cashier's cage at the Rio casino and split the prize. According to Dannenman, they had no agreement to do so in writing, but that "it was a gentleman's agreement".<br />
<br />
===Questions===<br />
<br />
Can playing tournament poker be legitimately described as an "investment" (one with admittedly significant risk, but potentially high return)?<br />
<br />
What factors would you look for to determine the attractiveness of this investment opportunity?<br />
<br />
==A game show for probabalists==<br />
<br />
A game show for the probability theorist in us all <br><br />
New York Times, Dec. 14, A19<br><br />
Gia Kourlas<br />
<br />
This article describes the new NBC game show called "Deal or No Deal"<br />
The rules are described on the NBC website as:<br />
<br />
<blockquote>The rules are simple. Choose a briefcase. Then as each round progresses, you must either stay with your original briefcase choice or make a "deal" with the bank to accept its cash offer in exchange for whatever dollar amount is in your chosen case. Once you decide to accept or decline the bank's offer, the decision is final. </blockquote><br />
<br />
To fully understand the game you should play it [http://www.nbc.com/Deal_or_No_Deal/game/ here]. Choose "game" from the options and go to the bottom of the page that comes up and choose "Start game".<br />
<br />
The Times article observes that it is not known how the bank determines its offers. Kourlas says that, at a meeting at his house to discuss the game, some thought the decisions my be based on probability concepts such as expected values and others thought that it had "psychological--but not logical--coherence. <br />
<br />
Of course the game as played on the Internet the bank clearly has a strategy for determing the offers and if this were known we would have an optional stopping problem if we were ineresting only in the expected amount we win.<br />
<br />
You can read more about this game including a discussion of the role of statistics in such a game [http://en.wikipedia.org/wiki/Deal_or_No_Deal here] from [http://en.wikipedia.org/wiki/Main_Page Wikipedia].<br />
<br />
===Questions===<br />
(1) The amounts that are in the briefcases at the beginning of the game are:<br />
<div style="float:left; width:55px;"><br />
{|border=1 cellspacing=0 cellpadding=1 width=50px|-<br />
|align=center|$0.01<br />
|-<br />
|align=center|$1<br />
|-<br />
|align=center|$5<br />
|-<br />
|align=center|$10<br />
|-<br />
|align=center|$25<br />
|-<br />
|align=center|$50<br />
|-<br />
|align=center|$75<br />
|-<br />
|align=center|$100<br />
|-<br />
|align=center|$200<br />
|-<br />
|align=center|$300<br />
|-<br />
|align=center|$400<br />
|-<br />
|align=center|$500<br />
|-<br />
|align=center|$750<br />
|}<br />
</div><br />
<div style="float:right; width:85%;"><br />
{|border=1 cellspacing=0 cellpadding=1 width=50px|-<br />
|align=center|$1,000<br />
|-<br />
|align=center|$5,000<br />
|-<br />
|align=center|$10,000<br />
|-<br />
|align=center|$25,000<br />
|-<br />
|align=center|$50,000<br />
|-<br />
|align=center|$75,000<br />
|-<br />
|align=center|$100,000<br />
|-<br />
|align=center|$200,000<br />
|-<br />
|align=center|$300,000<br />
|-<br />
|align=center|$400,000<br />
|-<br />
|align=center|$500,000<br />
|-<br />
|align=center|$750,000<br />
|-<br />
|align=center|$1,000,000<br />
|}<br />
</div><br />
<br clear="all" /><br />
<br />
(1) What is the expected amount in your initial suitcase?<br />
<br />
(2) Assume that the banker always offers the expected value of the amounts in the remaining suitcases. Would any strategy give you a higher expected winning then just accepting the banker's first offer?<br />
<br />
(3) If the bank does not offer the expected amount in the remaining suitcases, what is your optimal strategy to maximize your expected winning? <br />
<br />
(4) Why might you not want to use expected value in deciding on your strategy for playing this game?<br />
<br />
(5) Here is a remark from [http://www.freakonomics.com/blog/2005/12/22/the-sad-thing-about-deal-or-no-deal/ the Freakonomics Blog].<br />
<blockquote>Guessing the banker's offer is fun to do. Interestingly, in the Australian and Dutch version, this task is relatively simple: the offer as a percentage of the average remaining prize increases with every round, starting from about 5% to finally 100%. This rule can explain about 95% of the variation in the offers. I wonder if the US bank uses the same rule?</blockquote><br />
<br />
Does this seem to fit what is done on the internet version of the game?<br />
<br />
<br />
Sugested by Norton Starr and submitted by Laurie Snell.<br />
<br />
==New Form of Literary Criticism==<br />
<br />
[http://books.guardian.co.uk/news/articles/0,,1674327,00.html Da Vincy novel breaks code for success]<br><br />
''The Guardian'', Dec. 28, 2005<br><br />
John Ezard<br />
<br />
The discipline of statistics suffers when it practitioners venture into fields without the aid of a content expert. There is a temptation to deal with something which has popular appeal; use of multiple comparisons of easily acquired computer data can lead to inane predictions. In the past, ludicrous forecasts related the winners of presidential elections to whether the American League or the National League won the World Series; or, the sexual orientation of an individual depends upon whether a forefinger is longer than the ring finger. According to the British newspaper, ''The Guardian'', of December 28, 2005, statisticians are now into literary criticism, or at least what makes a book a bestseller.<br />
<br />
The team of statisticians headed by Dr. Alvai Winkler, formerly of Middlesex University, "assumes that much of success lies in the title" of the work. "Comparing these with a control group of less successful novels by the same authors, they found that the winning books had three common features; they had metaphorical, or figurative titles instead of literal ones; the first word was a pronoun, a verb, an adjective or a greeting; and their grammar patterns took the form either of a possessive case with a noun, or of an adjective and noun or of the words The ... of ..."<br />
<br />
Dr. Winkler states: "When we tested our model on 700 titles published over 50 years, it correctly predicted whether a book was a bestseller or not for nearly 70% of cases. This is 40% better than random guesswork [(70%-50%)/50% = 40%]. It is far from perfect but given the nature of the data and the way tastes change 70% accuracy is surprisingly good." However, despite the data dredging, the article points out that ''Harry Potter'' came in at 51% and ''The Da Vinci Code'' scored only 36%. The Winkler team, in an effort to avoid having its analysis look foolish, backpedals and predicts Dan Brown "will have a real bestseller next year with ''The Solomon Key''. Though its title structure is identical to ''The Da Vinci Code'', they count it as figurative 'due to its reference to the Greater and Lesser Keys of Solomon, medieval books about black magic.'" In other words, for "yes," read "no."<br />
<br />
Whether or not Dan Brown's new book approaches the financial and literary success of ''The Da Vinci Code'' will, of course, depend on ''The Da Vinci Code''. And one hopes, at least to some extent on what is inside the covers and presumably to chance as well (state of the economy, natural disasters, the phases of the moon, etc.). Titles come and titles go as in Hemingway's identical ''Fiesta'' and ''The Sun Also Rises'', not to mention Agatha Christie's penchant for multiple naming of the same book. The reader is encouraged to look up the original title of her brilliant novel, ''And Then There Were None'', to see how unconsciously prejudiced we used to be. Her last book, ''Sleeping Murder'', scored 83% and was deemed "the most perfect title." Nevertheless, this Agatha Christie fan claims it can't compare with some of her earlier novels when she was in her prime, regardless of the subsequent rechristenings of the titles.<br />
<br />
Unquestionably, under any conceivable criterion, a candidate for the dullest book title in creation would be ''Statistics in Britain, 1865-1930: The Social Construction of Scientific Knowledge'' by Donald MacKenzie. Never judge a book by its title; MacKenzie gives a fascinating presentation of the political and social mindset of the pioneers of statistics who invented, among other concepts, regression, correlation, and the t-test in order to advance a particular agenda which, embarrassingly enough, had eugenics in the forefront. Every practitioner of statistics needs to read this book.<br />
<br />
<br />
===Discussion===<br />
Do you think Winkler's claim that 70% correct is 40% better than random guesswork makes sense? If not how might you compare 70% correct to guesswork?<br />
<br />
Submitted by Paul Alper.<br />
<br />
==Mothers Know Best. Or Do They?==<br />
[http://online.wsj.com/article_email/SB113565052512831921-lMyQjAxMDE1MzI1NzYyNTcwWj.html Pestering a busy statistican]<br><br />
''Wall Street Journal'', Dec. 27, 2005, A1<br><br />
Anna Wilde Mathews in London and Peter Wonacott in Moradbad India.<br />
<br />
In a sense, we--statisticians and lay people--were spoiled by the famous study some 50 years ago relating lung cancer to cigarette smoking. Spoiled because the connection was so blatantly obvious in that smokers had a five to ten-fold increase in lung cancer over nonsmokers. Since then, most studies which tried to find culprits or saviors have produced far less striking results. A, let us say, mere 20%, as opposed to a 500 or 1000%, difference between a treatment and a placebo would be regarded nowadays as an achievement. Too many things which ought to promote health just don't seem to pan out when a careful experiment is done.<br />
<br />
One exception would seem to be the one our mothers drilled into us: eat your vegetables! According to the ''Wall Street Journal'' article, a 1992 article in the ''British Medical Journal'' by Ram Singh claims, "Heart attack victims who ate more fiber, fruits and vegetables for a year cut their risk of death during that period by almost half." The WMJ reports that "Singh's study has been cited more than 200 times in other scientific articles and guidelines for doctors." The newspaper further states that in other journals Singh "offered eye-popping evidence about the cardiac-health benefits of a good diet" which should include "fish oil, mustard oil, zinc, magnesium," and, of course those old standbys, "fruits and vegetables." Patients at his hospital are handed a card which advises in addition to the usual fruits and vegetables, "eating papaya, walnuts, lentils" and "a glass of whiskey every other day and about 15 minutes of yoga daily."<br />
<br />
Except perhaps for the whiskey, most of us would automatically nod our heads in agreement because it makes such good intuitive sense. Unfortunately, intuitively sensible though the advice may be, the WSJ article points out there is considerable reason to believe that Singh's results are bogus. By 1993 critics doubted that he could have conducted five distinct trials involving so many patients in such a short period. Furthermore, there were allegations that he "had tried multiple treatments simultaneously on patients and then written articles as if only one treatment was being used at a time." In addition, "He used some of the same patients in more that one study." Moreover, another paper of his to the BMJ had improper randomization with only the younger patients getting--you guessed it--the fruits and vegetables<br />
<br />
When the BMJ editor asked for the raw data, Singh who works in India, apologized because "termites had eaten crucial data." A British statistician was asked to review Singh's work and eventually concluded it was "either fabricated or falsified," and "was full of basic statistical errors and contradictions." The strangest aspect of the whole affair is the length of time the BMJ editor took to unravel the assertions made by Singh's original paper. When the editor was alerted to the alleged problems in 1993, a comedy of errors ensued. The statistician tapped to do the checking changed jobs and thus, several years went by. All the while, the editor was trying to hide his detective work from Singh. In 2002--ten years after publication--Singh "sent a copy of one of his articles with a serrated edge that he said had been gnawed by termites." Three further years go by--we are then half way through 2005--before "the BMJ carried a headline: 'Suspicions of fraud in medical research--Who should investigate?' along with a photo of a list of Dr. Singh's publications."<br />
<br />
Whether or not mothers know best, the mother of ''my'' child continues to believe that fruits and vegetables must be good for you despite the lack of statistical evidence. If she is typical, the public consequently feels it is a shortcoming of statistics if it can't verify the obvious. Fortunately for family harmony, unlike former President H.W. Bush, our daughter likes broccoli. As far as we know, she isn't into whiskey or fish oil.<br />
<br />
Submitted by Paul Alper.</div>Thekohser