I always look forward to hearing observations and advice from NPR's Weekend Edition math guy, Keith Devlin (his day job is Stanford math professor). Today's story was about the body mass index: Why it doesn't provide good evidence about someone's fitness (or fatness) level, and how it gained such a strong foothold in popular beliefs about weight. In Top Ten Reasons Why the BMI is Bogus, Devlin says:
"1. The person who dreamed up the BMI said explicitly that it could not and should not be used to indicate the level of fatness in an individual. The BMI was introduced in the early 19th century by a Belgian named Lambert Adolphe Jacques Quetelet. He was a mathematician, not a physician. He produced the formula to give a quick and easy way to measure the degree of obesity of the general population to assist the government in allocating resources. In other words, it is a 200-year-old hack.
2. It is scientifically nonsensical. There is no physiological reason to square a person's height (Quetelet had to square the height to get a formula that matched the overall data. If you can't fix the data, rig the formula!). Moreover, it ignores waist size, which is a clear indicator of obesity level.
3. It is physiologically wrong." And the story goes on. OK, so this doesn't mean we should be snarfing extra beer and brats over the holiday. But it is a great example of the tyranny of faulty evidence.
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