Monday, November 16, 2015
Update on Death Rates
I noted in an earlier post the surprising discovery that death rates for "middle aged" (i.e. age 45-54 year old) non-Hispanic white people in the U.S. have been rising, against a background of overall decreasing death rates in all other demographic categories.
As it turns out, subsequent analysis by other researchers has modified this conclusion. Here Andrew Gelman explains that in fact, this is true only for women. The death rate for men increased until 2005, then started back down. The reason for the mistake is interesting for those of you who care about ways to lie -- or just make a mistake -- with statistics. It turns out that during the period of analysis, the age composition of white non-Hispanic people within the 45-54 year old cohort increased. In other words, more of them were near 54 at the end than at the beginning. The death rate doesn't go up a lot from 45-54, but it goes up enough to wipe out the apparent effect for men.
This is a version of what is called an error of aggregation. In any case, the result is even more puzzling than the original analysis. How would you explain it.