Chance News 85

Quotations

“Journalists could help people grasp uncertainty and help them apply critical thinking to health care decision-making issues…rather than promote false certainty, shibboleths and non-evidence-based, cheerleading advocacy.”

-- Gary Schwitzer, at HealthNewsReview.org

"To treat your facts with imagination is one thing; to imagine your facts is another."

-- John Burroughs (1837-1921), quoted in Gary's talk at the conference
Science Writing in the Age of Denial, University of Wisconsin, Madison

Submitted by Paul Alper

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"A big computer, a complex algorithm and a long time does not equal science."

-- Robert Gentleman, quoted at One R Tip A Day

Submitted by Bill Peterson

Fish oil

Weighing the evidence on fish oils for heart health
by Anahad O’Connor, Well blog, New York Times, 11 April 2012

According to O'Connor,

Fish oil supplements have become some of the most popular dietary pills on the market, largely on the strength of medical research linking diets high in baked and broiled fish to lower rates of heart disease. Across the United States, annual sales of purified fish oil, commonly sold as omega-3 fatty acids, are in the neighborhood of a billion dollars. And in some parts of Europe, doctors routinely prescribe fish oils to patients with heart disease.

People who put their faith in fish oil supplements may want to reconsider. A new analysis of the evidence casts doubt on the widely touted notion that the pills can prevent heart attacks in people at risk for cardiovascular disease.

And well the people might. O’Connor is referring to “Efficacy of Omega-3 Fatty Acid Supplements (Eicosapentaenoic Acid and Docosahexaenoic Acid) in the Secondary Prevention of Cardiovascular Disease; A Meta-analysis of Randomized, Double-blind, Placebo-Controlled Trials” by S.M. Kwak, et al., to appear in the Archives of Internal Medicine. Not only did:

Our meta-analysis showed insufficient evidence of a secondary preventive effect of omega-3 fatty acid supplements against overall cardiovascular events among patients with a history of cardiovascular disease,

But also:

Furthermore, no significant preventive effect was observed in subgroup analyses by the following: country location, inland or coastal geographic area, history of CVD, concomitant medication use, type of placebo material in the trial, methodological quality of the trial, duration of treatment, dosage of eicosapentaenoic acid [EPA] or docosahexaenoic acid [DHA], or use of fish oil supplementation only as treatment.

Discussion

1. The authors started their meta-analysis with 1007 articles; eventually, after 181 studies were excluded as duplicates and others were dropped out for various other reasons, they were left with “14 randomized, double blind, placebo-controlled trials.” The total number of subjects in the 14 trials was 20, 485. As stated above, statistical significance was not to be seen. Two large studies of 11,234 and 18, 645 subjects, respectively which did show beneficial effects from fish oil were not included in the 14; they were rejected because they were “open-label” studies. Why are open-label studies suspect?

2. Why did the subjects in the placebo arm of the 14 studies receive various vegetable oils? Some of those subjects in the placebo arm received olive oil. Why might this “have disguised the ‘true’ benefit of omega-3 fatty acid supplementation?”

3. If not fish oil, O’Connor says the authors conclude that

it may make the most sense to spend your money on actual fish, rather than fish oil supplements.

They argue that by eating fish, you end up replacing other less healthy protein sources, like processed foods and red meat. For that reason, a diet high in fatty fish — one that includes at least two servings a week — may make a difference over the long term, they say.

If the above is correct, why are so many people eschewing fish for fish oil?

Submitted by Paul Alper

Choosing a spouse--really?

The purpose of spectacular wealth, according to a spectacularly wealthy guy
by Adam Davidson, New York Times Magazine, 1 May 2012

Davidson describes an interview with Edward Conard, one of Mitt Romney's former associates from Bain Capital, who has written a book entitled Unintended Consequences: Why Everything You’ve Been Told About the Economy Is Wrong. It is amusing to note the following, which appears that about halfway through the article:

There’s also the fact that Conard applies a relentless, mathematical logic to nearly everything, even finding a good spouse. He advocates, in utter seriousness, using demographic data to calculate the number of potential mates in your geographic area. Then, he says, you should set aside a bit of time for “calibration” — dating as many people as you can so that you have a sense of what the marriage marketplace is like. Then you enter the selection phase, this time with the goal of picking a permanent mate. The first woman you date who is a better match than the best woman you met during the calibration phase is, therefore, the person you should marry. By statistical probability, she is as good a match as you’re going to get. (Conard used this system himself.)

Discussion

1. They almost got the description of the optimal algorithm for the famous Secretary Problem correct. What is missing from this argument?

2. Do you believe that Conard actually used this system himself?

Submitted by Charles Grinstead

Comments

1. This is a long article, which describes Conard's argument as a defense of unbridled, winner-take-all competition. As a reminder that we heard much of this a century ago, Paul Alper sent the following quote:

The American Beauty Rose can be produced in the splendor and fragrance which bring cheer to its beholder only by sacrificing the early buds which grow up around it. This is not an evil tendency in business. It is merely the working-out of a law of nature and a law of God.

--John D. Rockefeller, address to the students of Brown University, quoted in Ida Tarbell (1904) The History of the Standard Oil Company

2. See also the post Incentive perversity, Economix blog, New York Times, 7 May 2012. University of Massachusetts economist Nancy Folbre points out that when economic rewards become too extreme, incentives can become distorted. She notes that high-stakes educational testing led to cheating to beat the system, out-sized contracts for star athletes led to an era tainted by performance-enhancing drugs. It's hard to imagine that business would be immune. She concludes that, "Good incentives are always a good idea. But it’s not as easy to design them as it might seem, because they should discourage a host of economic sins — not just sloth and fear, but also cruelty and greed."

TV and the shortening of life

Television viewing time and reduced life expectancy: a life table analysis
by J Lennert Veerman, et. al., British Journal of Sports Medicine, 15 August 2011

From the online abstract we read:

Results The amount of TV viewed in Australia in 2008 reduced life expectancy at birth by 1.8 years (95% uncertainty interval (UI): 8.4 days to 3.7 years) for men and 1.5 years (95% UI: 6.8 days to 3.1 years) for women. Compared with persons who watch no TV, those who spend a lifetime average of 6 h/day watching TV can expect to live 4.8 years (95% UI: 11 days to 10.4 years) less. On average, every single hour of TV viewed after the age of 25 reduces the viewer's life expectancy by 21.8 (95% UI: 0.3–44.7) min. This study is limited by the low precision with which the relationship between TV viewing time and mortality is currently known.

Conclusions TV viewing time may be associated with a loss of life that is comparable to other major chronic disease risk factors such as physical inactivity and obesity.

Needless to say, this highly speculative--but very quotable--statistical analysis has been picked up by every conceivable web site since last August. It just made its appearance in the Minneapolis Star Tribune: Can TV cut your life short?, by Jeff Strickler, 7 May 2012. The New York Times mentioned it a week earlier: Don’t just sit there, by Gretchen Reynolds, 28 April 2012.

Submitted by Paul Alper

Discussion

1. The NYT article describes a number of studies about the ill effects of inactivity. Their entire description of the Australian study reads, "researchers determined that watching an hour of television can snip 22 minutes from someone’s life. If an average man watched no TV in his adult life, the authors concluded, his life span might be 1.8 years longer, and a TV-less woman might live for a year and half longer than otherwise." What is missing here?

2. Elsewhere in the story, the NYT notes that "Television viewing is a widely used measure of sedentary time." What does this suggest about interpreting the Australian study?

Approval "statistic"

“Memo to Connecticut Democrats”, by Jonathan Pelto, May 7, 2012

From a CT blogger's website:

The following chart indicates how Connecticut Democratic voters rate Governor Malloy’s job performance. In politics we use a statistic that measures the rate of approval compared to the rate of disapproval – we call that the overall positive or negative rating of an individual (i.e. +/-). The higher the positive rating the better the candidate or elected official is doing.

Questions

1. Can you think of a reason why the June 2011 poll figures sum to 106?
2. The rightmost column heading might suggest that these figures are margins of error (percentage points), except for their size. If they had been margins of error, about how many people would have been in the sample on March 2011? Is that realistic?
3. According to the text, the rightmost column contains a “statistic that measures the rate of approval compared to the rate of disapproval.” How do you think that the blogger compared approval/disapproval figures to come up with the figures in the rightmost column? (While I couldn’t find a definition of “approval rating,” I did found that the blogger's "statistic" is pretty common; for example, see Wikipedia's "United States presidential approval rating".)
4. How might you have entitled the +/- column, in order to clarify its meaning?
5. The blogger opens the article by stating that Malloy's "support from members of [his] own party ... is at a breathtakingly low + 19 percent." Do you agree? What would you have said?

Submitted by Margaret Cibes