I think the Freakonomics authors talked about this study... the study's authors noticed there was some gaming of the statistics going on because while most stat

I think the Freakonomics authors talked about this study... the study's authors noticed there was some gaming of the statistics going on because while most stats dropped, the rate of certain offenses held steady. The stubborn offenses were the ones that were much trickier to reclassify as lower level crimes, like homicide or arson.