Progress Daily

People born under the astrological sign of Leo are 15% more likely to be admitted to hospital with gastric bleeding than those born under the other 11 signs. Sagittarians are 38% more likely than others to land up there because of a broken arm. Those are the conclusions that many medical researchers would be forced to make from a set of data presented by Peter Austin — if they applied the lax statistical methods of their own work.

Austin’s point was to shock medical researchers into using better statistics.

The confusion arises because each result is tested separately to see how likely, in statistical terms, it was to have happened by chance. If that likelihood is below a certain threshold, typically 5%, then the convention is that an effect is “real.” And that is fine if only one hypothesis is being tested. But if, say, 20 are being tested at the same time, then on average one of them will be accepted as provisionally true.

In his study, Dr Austin tested 24 hypotheses, two for each astrological sign. He was looking for instances in which a certain sign “caused” an increased risk of a particular ailment. The hypotheses were less than 5% likely to have come about by chance. However, when he modified his statistical methods to take into account the fact that he was testing 24 hypotheses, not one, the boundary of significance dropped dramatically. At that point, none of the astrological associations remained.

Unfortunately, many researchers looking for risk factors for diseases are not aware that they need to modify their statistics when they test multiple hypotheses. According to work by John Ioannidis, observational health studies that trawl through databases, rather than relying on controlled experiments, are likely to be completely correct only 20% of the time.

“Signs of the times,” The Economist

According to the World Health Organization, people further down the social ladder usually run at least twice the risk of serious illness and premature death of those near the top.

A possible explanation has been proposed in several papers by Linda Gottfredson and Ian Deary. The crucial points are that (a) social status correlates strongly and positively with IQ and other measures of intelligence; (b) intelligence correlates strongly with “health literacy,” the ability to understand and follow a prescription for disease prevention and treatment; and (c) intelligence is also correlated with forward planning — which means avoidance of health risks (including smoking) as they are identified.

In modern developed countries IQ correlates about 0.5 with measures of income and social status. The mean IQ of Americans in the Census Bureau’s “professional and technical” category is 111. The mean for unskilled laborers is 89. An American whose IQ is in the range between 76 and 90 is 8 times as likely to be living in poverty as someone whose IQ is over 125.

Intelligent people tend to be the most knowledgeable about health-related issues. In the past big gains in health and longevity were associated with improvements in public sanitation, immunization and other initiatives not requiring decisions by ordinary citizens. But today the major threats to health are chronic diseases — which require patients to participate in the treatment.

Deary was coauthor of a 2003 study in which childhood IQs in Scotland were related to adult health outcomes. Mortality rates were 17% higher for each 15-point falloff in IQ. Gottfredson cites a 1993 study indicating that more than half of the 1.8 billion prescriptions issued annually in the U.S. are taken incorrectly. The same study reported that 10% of all hospitalizations resulted from patients’ inability to manage their drug therapy.

A new Test of Functional Health Literacy of Adults can evaluate the problem in a mere 22 minutes. In a sample of 2,659 clinic patients in two urban hospitals, 42% did not understand the instructions for taking medicine on an empty stomach, and 26% did not understand when the next appointment was scheduled.

Smoking, obesity and sedentary living are more prevalent among the low-status. A 2001 study by the Centers for Disease Control & Prevention found that college graduates are 3 times as likely to live healthily as those who never got beyond high school.

“Why the Rich Live Longer,” by Dan Seligman

Receiving even small gifts creates the desire, often unconscious, to give something back, says Max Bazerman. Charities that send out free address labels get more in donations than those that don’t. Customers who are given a 50-cent key chain at a pharmacy spend substantially more in the store.

Conflicted individuals, says Prof. Bazerman, “continue to have doubts long after objective observers are convinced by the evidence,” as when some tobacco executives refused to admit that smoking is related to risk of cancer.

But simply disclosing financial ties, as many journals require of authors, may not help.

In a 2005 experiment done by Daylian Cain, volunteers were given advice about how much money was in a jar of coins. In some cases, the advisers were unconflicted, and the volunteers used the advice to make good guesses about the coins (which they saw only fleetingly and from a distance). In other cases, the advisers had a monetary incentive to overestimate the value of the coins. The volunteers knew this, and adjusted the advice downward. But they didn’t adjust enough, and overestimated the value.

“Simply Disclosing Funds Behind Studies May Not Erase Bias,” by Shirley S. Wang

Carsten Wrosch, Gregory E. Miller, Michael F. Scheier, etc., conducted 3 studies of 280 subjects and found that clinging to impossible dreams results in symptoms of depression and stress. (See “Giving up Unattainable Goals: Benefits for Health?“)

“We’re All Failures,” by David Serchuk

US blacks are twice as likely to be in poverty as non-blacks, according to the U.S. Census Bureau, and they make nearly $5,000 a year less, on average.

Roland Fryer has studied “acting white,” where black kids who work hard at school are said to be ostracized by their peers.

He sifted through a database of the social connections of 90,000 teens, judging a teen’s popularity based on whether other teens named them as a friend. His conclusion was that hardworking black and Hispanic children, unlike non-Hispanic white kids, lost friends if they studied hard.

Fryer points to similar behavior by Italian immigrants in 1950s Boston; by the Burakumin in Japan, who are descendants of what was traditionally a low caste; and some traditional Amish communities.

“The Achievement Gap,” by Tim Harford

Psychological well-being and high blood-pressure are thought by clinicians to be inversely correlated. Blood-pressure problems can be reported more objectively than mental well-being. Using data on 16 countries, the paper finds that happier nations report lower levels of hypertension.

“Hypertension and Happiness across Nations,” by David G. Blanchflower & Andrew Oswald

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Recent research has argued that psychological well-being is U-shaped through the life cycle. The difficulty with such a claim is that there are likely to be omitted cohort effects (earlier generations may have been born in, say, particularly good or bad times). Hence the apparent U may be an artifact. Using data on approximately 500,000 Americans and Europeans, this paper designs a test that makes it possible to allow for different birth-cohorts. A robust U-shape of happiness in age is found. Well-being reaches a minimum, on both sides of the Atlantic, in people’s mid to late 40s.

“Is Well-being U-Shaped over the Life Cycle?” David G. Blanchflower & Andrew J. Oswald