Bruce McCullough points me to this note by Bernard Harcourt on the negative correlation between the rates of institutionalization and homicide. Basically, when more people have been in mental hospitals, there have been fewer homicides, and vice-versa.
It makes sense since, presumably, men who are institutionalized are more likely to commit crimes, so I’m surprised that Harcourt descrbes his results as “remarkable–actually astounding. These regressions cover an extremely lengthy time period . . . a large number of observations . . . and the results remain robust and statistically significant . . .” With a large data set, you’re more likely to find statistically significance. Especially when the main result is so plausible in the first place.
Harcourt concludes with some interesting comments about the applicability of his results. (I’d also like to recommend the paper by Donohue and Wolfers on death penalty deterrence as a model example of this sort of analysis.)
P.S. See here for an update by Harcourt, where he explains why he finds his results surprising. I’m not convinced–I believe the results are important, just not that they’re suprising.
Funny stuff
Harcourt’s blog entry had some amusing comments: Continue reading →