An excellent post by Mark Draughn that reminds how we get the behavior we incentivize. In this case the NYC govt incentivized its police to ignore violent crimes and to make bogus arrests to boost their cleared-case stats:
This is a standard recipe for disaster in quality control — and CompStat is at heart a statistical quality control program. Take a bunch of people doing a job, make them report quality control data, and put pressure on them to produce good numbers. If there is little oversight and lots of pressure, then good numbers is exactly what they’ll give you. Even if they’re not true.
Worth reading in full.