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CHANCE News 3.09
(11 June to 8 July, 1994)
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Prepared by J. Laurie Snell, with help from Jeanne
Albert and William Peterson, as part of the CHANCE
Course Project supported by the National Science
Foundation and the New England Consortium for
Undergraduate Science Education.
Please send comments and suggestions for articles to:
jlsnell@dartmouth.edu
Back issues of Chance News and other materials for
teaching a CHANCE course are available from the Geometry
Center Mosaic (http://www.geom.umn.edu/) in their
Online Document Library.
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It is time for us to reclaim our numbers,
our truth.
Cynthia Crossen
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IN THIS NEWSLETTER
======================================= FROM OUR READERS Goran Djuknic sent us the Bureau of Consular Affairs [Public Notice 1974] describing the rules for the visa lottery. He noted that, at first, it is stated that every applicant will have an equal chance of winning but later every applicant "within a given region" has an equal chance of winning. The following newspaper article describes this visa lottery <<<========<<
>>>>>==========>> Immigrants' American dream: winning a visa.
The Washington Post, 1 July 1994, B3 Ann O'Hanlon
Over 9 million people have applied since June 1 for a lottery which will give visas to 55,000 immigrants. The purpose of the lottery is to balance a skewed distribution of immigrant nationalities resulting from giving preference to those with family ties and job skills. Countries that sent more than 50,000 legal immigrants to the United States in the past 5 years are not eligible. In this article, a State Department spokesman said, "it is all random and nobody's chances are better than anybody else's". As Djuknic points out, this is not correct because the number of visa numbers allotted for each region is chosen to give a greater share of numbers to low admission regions. Obviously, one's chances in this lottery depend upon both the allotment for a region and the number of people who apply in this region. The procedure for applying is very simple but swindlers are making money by putting ads in papers read by immigrants such as "Green Card!!! Try Your Luck!! $20 a person and $35 per family. <<<========<<
>>>>>==========>> Jim Baumgartner suggested the following book: Tainted Truth: the Manipulation of Fact in America by Cynthia Crossen, Simon and Shuster 1994. This book might well be required reading for students in a CHANCE course. Cynthia Crossen argues that a lot can go wrong with statistics that cannot be blamed on the whims of chance. Her many insightful observations include: For very good reasons having little to do with statistics, Coca Cola taste studies show that people prefer Coke and Pepsi Cola studies show that they prefer Pepsi. Polls are a politician's weapon and are frequently designed and interpreted accordingly. A study paid for by the tobacco company is not likely to conclude that second hand smoke is dangerous and medical researchers funded by drug companies may not be completely immune to bias. Parameters in risk models can and often are chosen judiciously to make the outcome agreeable to the developer of the model. Expert witnesses in the courts are paid a lot of money to try to reach different conclusions from the same statistical data. Each chapter has numerous examples. Here are chapter titles and examples from each chapter that I particular enjoyed. Chapter 1: The Study Game Example: The author asked Gallup five questions about credibility and information. Gallup responded by making the questions into a survey which they carried out for a modest fee ($4,500). Chapter 2: The Truth about Food. Example: the oat bran mania of the 80's and the stampede against Alar started by the 60 Minutes report. . Chapter 3: Numerical Lies of Advertising: Example: An account of the taste tests carried out by Coca Cola and Pepsi companies. Chapter 4: False Barometers of Opinion: Example: Polls taken at the time of the Clarence Thomas hearings indicated that people did not believe Anita Hill. It is likely that these polls influenced the outcome of the Thomas appointment. However, similar polls a year later indicated that Anita Hill was at least as believable, if not more so, than Clarence Thomas. Chapter 5: False Truth and the Future of the World Example: The environmental battle between disposable and cloth diaper industries. A 1988 study by the cloth diaper industry served as ammunition for opponents of disposable until this study was neutralized by a 1990 study produced by Proctor & Gamble. This in turn was followed in 1991 by another study sponsored by the cloth diaper industry showing that cloth diapers were environmentally superior. Chapter 6: Drugs and Money Example: Two conflicting studies on the effectiveness of a drug based on the same data were submitted simultaneously to the New England Journal of Medicine. The author who found the drug effective had large grants from the pharmaceutical companies and had his paper accepted. The other with no grants had his paper rejected by the NEJM but then accepted by the Journal of the American Medical Association but this did not lead to a happy ending. Chapter 7: Research in the courtroom Example: The account of the Dalkon Shield case is interesting but I would have preferred DNA finger-printing. Chapter 8: Solutions Example: I liked the recommendation that high schools and colleges teach critical assessment of such news. In other words, Take a chance on CHANCE. <<<========<<
>>>>>==========>> OTHER RELEVANT INTERNET SOURCES Oncolink (The University of Pennsylvania Multimedia Oncology Resource) is a prize winning Mosaic that provides all kinds of news on cancer. The address is http://cancer.med.upenn.edu/. Oncolink has lots of interesting studies, EPA reports survey articles, etc. many of which are related to Chance News. The treatment of cancer and power lines is the most complete discussion of this problem that I have see anywhere. I would encourage you to browse around yourself but here are a few things I found in my browsing.
Cancer and Power Lines, emf etc.
Spiritual Well-Being: A Review of the Research Literature
Decision Support for Patients with Breast Cancer
FDA Statement on Nicotine and Cigarettes
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>>>>>==========>> The Electronic Newsstand gopher://gopher.internet.com:2100/11/ This newsstand has a wide variety of journals some of which have articles relevant to Chance News. Typically, the journal includes the table of contents of the current issue and one or two articles from this issue. This is the case, for example, for the journals "Discover", "The Economist" and the "Skeptical Inquirer" of special interest to us. Occasionally you find more complete set of articles in the current issue as, for example, is the case with "The Scientist". It is fun to browse, and in our own browsing we found the following article for this chance news: Trials and errors in breast-cancer research The Journal of NIH Research July 1994 Nancy Touchette The author states, "It wasn't meant to be fought this way. But leaders of the National Cancer Institute (NCI), the chief strategists in the War on Cancer, are caught in a crossfire." This crossfire started with the revised mammography-screening guidelines, and was followed by charges that the Breast Cancer Prevention Trial may have seriously understated the potential risk of tomoxifen, and the charges that the NCI tolerated improper enrollment of patients in other breast-cancer trials. In the process of describing this crossfire we learn a lot the current state of our knowledge on some of the most important on-going cancer studies. ======================================= CURRENT NEWS ======================================= Space station faces danger from flotsam
The New York Times, 27 June, 1994, pg. A1 William J. Broad
This article discusses NASA's estimate of the chance that the international space station, due to be built from 1997 to 2002, will be penetrated by "space junk"-- dead satellites, shattered rockets, and other man-made debris. The chance of being hit is given at 1 in 5 over the course of its construction and expected 10-year life. The article explains that the "probability means that, if there were five such stations, experts would expect one to be hit." For comparison, the overall risk of a catastrophic collision that causes the death of astronauts or the destruction of the station is given at "1 chance in 10". The article states that there are "perhaps 150,000 objects that could penetrate the space station," of which 7000, "ranging from the size of a school bus to the size of a baseball," are tracked by the military. The remaining objects are too small to track. The size of the planned station itself is 361 by 290 feet-- larger than a football field. DISCUSSION QUESTION: The Russian space station Mir has been in orbit for eight years, and apparently has suffered no penetrations from space junk. How could you determine the chance of this happening, (assuming the probabilities given in the article are correct)? <<<========<<
>>>>>==========>> Testing the blood 3 ways.
New York Times, 9 July 1994, A8 Gina Kolata
This article explains the blood test reported in the hearing leading to the judge's decision that O. J. Simpson must stand trial for murder. In this test, blood found at the scene of the crime was compared with that of the suspect O. J. Simpson and the two victims, his former wife and Ronald Goldman. Serology proceeds by looking at proteins in the blood that occur in people in different forms. The most well known protein determines the ABO grouping or blood type. Simpson's blood type was A as was his former wife. Ronald Goldman, the other victim, had type O. The second protein they looked at, called ESD, has three variants, and in this case all three had the same type. The third protein, PGM, has 10 different forms. Here Simpson had the same type as the bloodstain found at the scene of the crime, and Mrs. Simpson and Mr. Goldman had different types. In an accompanying article, it is stated that estimates of the frequencies for these types were obtained by using blood tests run by the Los Angeles police department. Naturally, these estimates were multiplied together to obtain an estimate that 1 person in 200 had the types of proteins that Simpson had. The defense observed that between 40 and 80 thousand people in Los Angeles should also have these three types. One of the few attempts to estimate these from national data was published in 1987, but this study did not have enough data to include Asians or Hispanics so was hardly applicable to Los Angeles. From the results of this study it is estimated (again by multiplying the individual estimates) that among the white population 1 in 150 would have the types of the proteins that Simpson has and, in a black population, 1 in 500. DISCUSSION QUESTIONS: 1. The prosecutor tries to narrow down the 40,000 to 80,000 people in Los Angeles that have the same blood characteristics as Simpson by asking "But how many of these would have a bloody glove in their house?" The defense responds: No, you should ask "How many have some any bloody or suspicious object such as a knife." Which one is correct? 2. An Los Angeles Times article discussing the possibility of a death sentence if Simpson is found guilty remarked: "The death penalty is rarely imposed in spousal murders. Indeed, of the 2,812 men on Death Row nationwide, only 34, or 1.2%, killed their wives or ex-wives". Are these statistics convincing? 3. How would you determine if multiplying the frequency of the three protein types is reasonable? <<<========<<
>>>>>==========>> Embattled tobacco: one maker's struggle-1.
Embattled tobacco: one maker's struggle-2.
Embattled tobacco: one maker's struggle-3.
The New York Times, 16, 17, 18 June, 1984 Philip J. Hilts
Based on documents from the archives of the Brown & Williamson Tobacco Corporation, this three-part series describes how the major American tobacco companies chose to publicly downplay or even deny the results of studies, many conducted by their own research departments, on the health risks and physiologically addictive properties of smoking cigarettes. For example, the second article states that after an internal study from 1963 found evidence of significant physiological effects from smoking, considerable effort was put toward creating what the company called "a device for the controlled administration of nicotine"--- a "safer" cigarette with equal (or even greater) nicotine levels. A top researcher for Brown & Williamson's sister company, British-American Tobacco (Batco), described Batco in 1967 as being "in the nicotine rather than the tobacco industry." But when questioned in April of this year by the House Subcommittee on Health and the Environment, each of the seven top executives in the American tobacco industry stated that nicotine is not addictive and that cigarettes may not cause cancer. Meanwhile, on 17 June, 1994 a spokesman for Brown & Williamson is quoted as saying: "The tobacco industry was and is just as interested in research on smoking and health as those outside the industry. Our position continues to be that there are health risks statistically associated with smoking, but there is no conclusive evidence of a causal link between tobacco use and disease." The third article includes a "Chronology of Concern" that lists some of the results of major studies on tobacco and disease since the 1950's, along with actions taken by tobacco companies and government agencies. DISCUSSION QUESTIONS: 1. Referring to the statement by the industry spokesman, above, what do you think is meant by the phrases "statistically associated", "causal link" , and "conclusive evidence"? 2. In testimony before congress, Andrew W. Tisch, chairman of the Lorillard Tobacco Co., stated that "We have looked at the data and the data we have been able to see has all been statistical data that has not convinced me that smoking causes death." What do you think of this remark? <<<========<<
>>>>>==========>> Were you mislead? The Boston Globe, 3 July 1994, p7. Paid advertisement, Philip Morris USA
This advertisement reprints an article from Forbes MediaCritic entitled "Passive Reporting on Passive Smoke", by Jacob Sullum, the managing editor of Reason magazine. (This is clearly related, though not identical, to Sullum's recent National Review article; see CHANCE News, June 10, 1994) The central theme is that the media have been totally uncritical in their acceptance of the EPA's claims of evidence linking environmental tobacco smoke (ETS) to cancer. For example, the EPA examined 30 epidemiological studies looking for a link. While most of the studies found a positive association, this association was statistically significant in only six. Why, Sullum asks, has the issue of significance been ignored in press reports? Sullum also notes that the risk ratios associated with ETS are an order of magnitude lower than those for smokers. He complains that the news has been reported in a way that leads people to think that the evidence is just as strong for passive smoking as for active. Recent studies indicate that the average male smoker is 20 times more likely to develop lung cancer than a male nonsmoker; the corresponding risk ratio for women is 10 to 1. By contrast the EPA estimated that a woman living with a smoker is 1.19 times as likely to develop lung cancer as a woman who lives with a non-smoker. Sullum states that, with risk ratios this small, it is difficult to rule out other confounding variables, such as diet and pollution. James Enstrom, a UCLA professor of epidemiology, is quoted as saying: "You're talking about risk ratios so close to 1.0 that it's really beyond the realm of epidemiology." DISCUSSION QUESTIONS: 1. At one point, noting the media's failure to explain that an association was not statistically significant, Sullum explains that this means "the probability that the result occurred purely by chance was greater than 5%." Is this an accurate description? 2. In a section entitled Weasel Words, Sullum complains about phrases describing evidence that 'suggested there may be an increased...risk' or 'shows an apparent pattern' or 'appears to be associated.' He states that "in rigorous science, close doesn't count". Comment. 3. Sullum writes that "no study has ever found 'statistical proof that secondhand smoke caused cancer with certainty.' (In fact, it is impossible for an epidemiological study to provide such proof)." Does this mean that all epidemiological research is worthless? What would constitute "statistical proof with certainty?" <<<========<<
>>>>>==========>> Psi in psychology. SKEPTICAL INQUIRER, Summer 1994, pg. 351 Susan Blackmore
A recent paper in one of psychology's most prestigious academic journals, Psychological Bulletin (Vol. 115, 1994, 4-18.) forms the subject of this article by Susan Blackmore, a parapsychology researcher for the past 20 years. The paper, entitled, "Does Psi Exist? Replicable Evidence for an Anomalous Process of Information Transfer", concerns recent research on the existence of ESP by parapsychologist Charles Honorton and psychologist Daryl Bem. Blackmore remarks, "Bem's high profile and the respect he is accorded by psychologists will ensure that [their paper] is taken seriously." Honorton and Bem's paper concerns experiments in sending and receiving "telepathic" information using a procedure, pioneered by Honorton, known as a "ganzfeld". In the experiment, a person called the "receiver" is deprived of any outside sensory stimuli, while another, the "transmitter", concentrates on one of four randomly selected images. In general the ganzfeld is designed to limit the possibility of fraud or sloppy technique. The paper published in the Psychological Bulletin claims to have produced results with a 40 percent success rate, while a 25 percent success rate would be expected by chance alone. For more information about the history of ESP research and a thorough description of the ganzfeld procedure, see the article Inside Story: Talking Heads. The Guardian Weekend Page, 25 March, 1994, pg. 34 Simon Beckett. <<<========<<
>>>>>==========>> Completing math literacy.
Star Tribune, 1 July 1994, pg. 3B Jim Dawson
This article from a Minneapolis newspaper describes the recent workshop for high-school teachers about teaching the CHANCE course held at the University of Minnesota. The students were 30 junior and senior high school math teachers from Minnesota. In the article there are examples of topics covered in classes, such as margin of error and the reliability of political polls, and DNA fingerprinting in the courts. A typical workshop activity is also described in some detail: the design and execution of an experiment to determine the best of 12 chocolate-chip cookies. A syllabus for this course can be found on the CHANCE Mosaic. DISCUSSION QUESTIONS: 1. Here is an example of a discussion question about polling and margin of error used at the workshop. A poll in the Star Tribute says that "one can be 95% confident that error due to sampling will be no more than plus or minus 4.4 percentage points." A poll in the New York Times taken in Iowa says that "In theory, in 19 out of 20 cases the results based on such samples will differ by no more than 3 percentage points in either direction by what would have been obtained by interviewing all adult Iowans." These are both attempts to explain the concept of margin of error. Do they amount to the same thing? If not, which do you think is the more accurate description? Where do the 4.4 and 3 percent come from? 2. Mr. Dawson wrote that the second of the two polls explains margin of error this way: `In theory, in 19 out of 20 cases the results based on such samples will differ by no more than 3 percentage points in either direction.' How does this differ from the explanation given in question 1? 3. According to the article, one participant apparently used a theory "from a discreet [sic] mathematics course he had once taken" to help with the chocolate-chip cookie experiment. What do you suppose is taught in a "discreet" mathematics course? <<<========<<
>>>>>==========>> Early warnings, early worries.
The Economist, 18 July 1994, Pg. 91
This is a remarkably complete story about problems related to medical screening. The article begins with the medical problems caused by false positive and false negative outcomes. Such outcomes can lead to additional expensive tests, unnecessary and sometimes harmful treatments, and emotional problems. The issues are illustrated in terms of a number of specific diseases and screening processes. The author discusses current problems associated with genetic testing and future problems anticipated as these tests become more common. Again specific diseases and screening processes are discussed. The author remarks that the ability to develop new screening tests is running ahead of new cures and clearly thinks that screening is in danger of getting out of control. <<<========<<
>>>>>==========>> Implant study too small for final word.
The New York Times, 28 June, 1994, pg. A16 Letter to the Editor Sidney M. Wolfe, M.D., and Joanne C. Mott
This Letter is in response to a 16 June news article which reported on a study by the Mayo Clinic. The study, conducted to determine if there is a link between silicone breast implants and connective tissue diseases such as rheumatoid arthritis, found no evidence of such a link. The authors criticize the study for not addressing problems which they claim are "unequivocally caused by silicone implants", including delayed diagnosis of breast cancer and implant rupture. They also condemn the study for its small sample size, stating that there is "...a low probability that such a small sample will detect a statistically significant increase in connective tissue diseases among women with breast implants." For example, the authors claim that the probability that the study would detect a doubling of the risk of these diseases is 31 percent. DISCUSSION QUESTION: How do you think the 31 percent figure was determined? <<<========<<
>>>>>==========>> Pregnancy and breast cancer pose lethal risk.
Los Angeles Times, 24 June, 1994, pg. A3 Thomas H. Maugh II
This article reports on a study published in The Lancet by the M.D. Anderson Cancer Center in Houston which found that women who are pregnant when diagnosed with breast cancer are 3.26 times as likely to die from the disease as women who are not and never have been pregnant. If the woman is not pregnant, there is still a higher risk of mortality if she has been pregnant during the past five years, with the highest risks associated with more recent pregnancies. The results are based on studies of 407 women in their 20s. There has been evidence that younger women with breast cancer generally fare worse than older women, and, according to Dr. Vincent F. Guinee of M.D. Anderson, the results from this study show that "pregnancy itself is responsible." However, the article states that the increased mortality rate for pregnant women should apply to women of all ages. DISCUSSION QUESTIONS: 1. The article says that when the researchers "adjusted for the stage of the disease at the time of detection-- the size of the tumor, the number of lymph nodes involved and so on--the risk was reduced, but the women were still 2.83 times as likely to die. What do you think this means? 2. According to Eugenia Calle of the American Cancer Society, women in their 20s represent less than 1% of all breast cancer cases. On the other hand, the article states that one in every 2,426 women under 30 develops breast cancer, compared to one in 96 for women aged 45. Over a woman's life span, the risk is one in nine. What do these numbers mean? <<<========<< >>>>>==========>> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! CHANCE News 3.09 (11 June to 8 July 1994) !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Please send suggestions to: jlsnell@dartmouth.edu
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