Friday, May 01, 2009

Google Hot Trends: Crime Mapping

Crime Mapping is a Google hot trend that peaked at #3 about 6 hours ago, with 21% of search volume in Los Angeles, CA and 6% of search volume in Montclair, CA. It's now at #9. Here's the most recent graph from Google Hot Trends:



Crime mapping is used by analysts in law enforcement agencies to map, visualize, and analyze crime incident patterns. It is a key component of crime analysis and the CompStat policing strategy. Mapping crime, using Geographic Information Systems (GIS), allows crime analysts to identify crime hot spots, along with other trends and patterns. CrimeMapping.com is one of the major websites that provide information about recent crime activity by neighborhood. ClearMap is the Chicago Police Department offering. Using SpotCrime, it's possible to look at crime mapping in Dublin:
http://www.spotcrime.com/ie/dublin

Economists have some timely insights to offer on the cyclicality of crime behaviour. Derek Deadman and Ziggy MacDonald from the University of Leicester have shown that the general level of recorded crime fell in the United States and many European countries in the ten years previous to 2008. However, a recent issue of Scientific American asks "Will the Recession Spark a Crime Wave?". This fear is also becoming notable in the American media: Will Recession Make Cities Dangerous Again?

Bruce Weinberg from Ohio State University and his collaborators Eric D. Gould of Hebrew University and David Mustard of the University of Georgia have examined the crime behaviour of young males with no more than a high school education — the demographic group that commits the most crime. These authors find that average wages and unemployment rates were directly linked to the incidence of property crimes. Rick Rosenfeld, a criminologist at the University of Missouri–St. Louis, says: “I don’t think that newly unemployed people become criminals,” Rosenfeld notes, but “marginal consumers—the shopper who goes to discount stores—many of those consumers turn to street markets during an economic downturn. These are often markets for used goods, but some are stolen goods. As demand increases, incentives for criminals to commit crimes expand.”

Kevin Denny and Colm Harmon from UCD, along with Reamonn Lydon from the University of Warwick, have done an "Econometric Analysis of Burglary in Ireland". They model the level of burglary in Ireland between 1952 and 1998. The share of young males in the population is associated with higher levels of crime. Imprisonment and detection act as powerful forces for reducing crimes. The effects of aggregate consumption are more difficult to pin down but Denny, Harmon and Lydon show that higher spending is associated with more lucrative but probably fewer crimes. One somewhat surprising result is that they were unable to find any robust effect from direct measures of labour market activity such as unemployment rates or wage levels.

5 comments:

Kevin Denny said...

Thanks for the plug for our burglary paper, Rea Lydon was also an author.

Martin Ryan said...

My apologies to Rea.

I was looking at part of the Ideas page that said the following:

Additional information is available for the following registered author(s):

Colm P. Harmon
Kevin John Denny

So my eye just skipped over the main author info.

The paper is very topical given that Ireland has gone back into recession.

Kevin Denny said...

I have largely forgotten whatever I knew about crime trends. Cyclicality is a big issue though in the literature I think. I also think you get different patterns for crime against property compared to crime against the person. I don't think there is any evidence to suggest that the current recession will generate a crime wave.

I am puzzled about the Spot Crime data for Dublin. It looks too low: it picks up shootings but it would appear there were no burglaries or vandalism in Dublin for the last three months. Shurely shome mishtake?

Martin Ryan said...

Kevin,

Although you may not have looked at crime trends recently, you still know a lot more about the available data than I do. That SpotCrime data for Dublin must be limited to a narrow range of crimes.

I'm most interested in your thought that there is no evidence to suggest that the current recession will generate a crime wave.

From a theoretical perspective,
Rick Rosenfeld, a criminologist at the University of Missouri–St., says: “I don’t think that newly unemployed people become criminals,” but “marginal consumers—the shopper who goes to discount stores—many of those consumers turn to street markets during an economic downturn. These are often markets for used goods, but some are stolen goods. As demand increases, incentives for criminals to commit crimes expand.”

This suggests that the problem may be largely demand-driven, which is attuned to a cyclicality argument. This is definitely interesting for the Justice dept. from a planning perspective (e.g. should there be more police hired during a recession?) but it would also be useful to know whether there are different patterns for crime against property compared to crime against the person.

Kevin Denny said...

Well we don't find labour markets effects which was surprising but it was a very robust result as far as I remember. The supply side effect works the other way: as GNP falls there is less to steal.

Public sector cutbacks are affecting the Gardai like everyone else so one to watch.

Also worth bearing in mind is the argument due to Morgan Kelly & others that higher inequality leads to more crime, mostly based on US data. I am not sure that its a very robust finding: I saw some alternative evidence recently.