Category: Medicine
Doctors are very ignorant of statistics
Here is a bit from Gerd Gigerenzer:
The science fiction writer H G Wells predicted that in modern technological societies statistical thinking will one day be as necessary for efficient citizenship as the ability to read and write. How far have we got, a hundred or so years later? A glance at the literature shows a shocking lack of statistical understanding of the outcomes of modern technologies, from standard screening tests for HIV infection to DNA evidence. For instance, doctors with an average of 14 years of professional experience were asked to imagine using the Haemoccult test to screen for colorectal cancer. The prevalence of cancer was 0.3%, the sensitivity of the test was 50%, and the false positive rate was 3%. The doctors were asked: what is the probability that someone who tests positive actually has colorectal cancer? The correct answer is about 5%. However, the doctors’ answers ranged from 1% to 99%, with about half of them estimating the probability as 50% (the sensitivity) or 47% (sensitivity minus false positive rate). If patients knew about this degree of variability and statistical innumeracy they would be justly alarmed.
The lead is from Crooked Timber, through BlackTriangle.org.
Will life extension increase risk aversion?
Scientist Tom Johnson says that humans someday might live to 350 years old. Aubrey De Grey argues that as our lifespans become longer, we might stop taking high-speed automobile trips. Why risk losing so much, and after all, what would the hurry be?
FuturePundit suggests that perhaps our level of risk-taking behavior is regulated by our biology and hormonal systems. So if driving a car doesn’t “feel too risky” now, living to 350 won’t change this, perhaps we were never making an intertemporal calculation in the first place. Furthermore, it is young males who take the most risks, and they have large numbers of years left to lose. So giving us more years might not change our behavior that much. FuturePundit then wonders how drugs and neuroscience engineering might change this conclusion. What if you could take drugs that would make you more averse to risky behavior? Might you then, sitting alone in your room, ponder your remaining 320 years and decide to clutch on to them?
Cannabis Emptor
When goods are prohibited, quality tends to fall because of lack of competition and legal recourse. Quality in illegal markets, however, may still beat that available from government production. Health Canada spends millions of dollars growing marijuana for distribution to patients with medical need. The government grown pot is so awful, however, that patients are returning their 30 gram bags and asking for refunds! The government certifies and advertises that their product contains 10.2% THC but independent labs report only 3% THC. Furthermore, the government pot is contaminated with lead and arsenic. “This particular product wouldn’t hold a candle to street-level cannabis,” said Philippe Lucas of Canadians for Safe Access, the group that sponsored the tests. Thanks to Eric Crampton for alerting us to this story.