Tuesday, January 12, 2010

Happy to have blown a forecast

Last winter, I wrote two posts that discussed "rational" crime. The gist of the posts was that the standard rational choice model predicted that as the economy soured and legitimate economic opportunities decreased, crime, especially property crime, was likely to increase. The posts cited economic studies that indicated that a one percent increase in unemployment was associated, on average, with a one percent increase in the property crime rate. In one of the posts, I wrote that "people, business owners, and law enforcement will need to be more vigilant during the tough economic months ahead."

Well, it's a year later, and preliminary crime statistics for 2009 for Greensboro and the rest of the U.S. are in. For the first half of 2009, the FBI reports that
  • property crimes were down three percent (mostly due to a decrease in burglaries), and
  • violent crimes were down 12 percent (including a one-third drop in rapes and a 23 percent drop in aggravated assaults).

Okay, well, that's just one city and half a year (e.g., does anybody really believe that Greensboro's total year burglary rate will be down?). What do the statistics for the U.S. indicate?

For the entire U.S., the FBI reports a six percent drop in property crimes and a four percent drop in violent crimes.

Like any good empirical researcher, I can remind people that the statistics are preliminary and give a dissertation on the problems with the statistics. I can also point to the empirical association between the economy and crime rates representing an "expected" outcome with considerable variation around that expectation (think, e.g., about hurricane forecasts). I could even write that "people, business owners, and police departments" seem to have heeded my advice (judging from my site's stat counter, those 25 viewers were very influential).

But the bottom line is that the outcome did not match up with expectation, which is good news for most people.