Wednesday, February 20, 2008

Gangs and Crime - or is it Crime and Gangs?

Tita, G., & Ridgeway, G. (2007). The Impact of Gang Formation on Local Patterns of Crime Journal of Research in Crime and Delinquency, 44 (2), 208-237 DOI: 10.1177/0022427806298356

Blogging on Peer-Reviewed ResearchBefore we head away from gangs completely, I wanted to bring up this paper looking at the connection between gangs and crime. Obviously, most gangs are heavily associated with crime in the areas in which they operate. The 10% of youth who join gangs are responsible for 80-90% of the crime that occurs in a given community. So which comes first? Basically, there are three theories for how the two are related:
  • social facilitation - once a large group of juveniles congregate, they become more likely to commit crimes, and it is easier for them to do so (more lookouts, getaways, etc.).
  • selection - the juveniles who are already committing crimes are likely to band together out of common interests, or for utilitarian reasons.
  • enhancement - this combines facilitation and selection. Essentially, once the juveniles who are already committing crimes band together, they become much more effective and efficient.
The social facilitation and enhancement theories both predict that crime rates will go up after the establishment of a gang, while selection theory predicts that it will be relatively stable. Furthermore, facilitation can be separated from enhancement in that facilitation predicts there will be more people committing the crimes, whereas enhancement predicts that the same people will just be committing more crimes.

To test which one of these theories holds, the authors went to a site of emerging gang activity: Pittsburgh, PA. In addition, they wanted to test the theory that gangs inhibit certain types of crime, like property violence against local shopkeepers. (Personally, this sounds more like Organized Crime and "protection" to me, though I know gangs in LA run similar rackets with the local street vendors.) The investigators were able to draw causal conclusions from their dataset because prior to 1992, there was no gang activity in Pittsburgh. Looking at the two years before this time (90-91), the two years during "establishment" (92-93), and the two years postgang (94-95) it's possible to discern trends in crime rates that correspond with the introduction and maintenance of gang activity.

The authors obtain their crime data from 911 call records (problematic, yes, but they attempt to address these fears in the paper). They also try to disaggregate their data by defining, with the help of locals, what constitutes gang turf, and denoting areas as "carriers" of gang activity, or "set spaces," neighboring areas adjacent to gang turf, and non-neighbors. Comparisons of different types of crimes in these different areas is shown in Figure 2, and in Figure 3 they weight the crime rates to eliminate confounding factors, like racial makeup, income level, etc. There's an assumption that crime rates in non-neighboring areas are generally unaffected by gang activity, so comparing rates in these two areas can give an estimation of the effects of gangs on crime.

Looking at Figure 3, it's clear that after gangs gained a foothold in the 92-93 time period there were spikes in reportings of drug crimes, robberies, and shots fired in gang neighborhoods. All of these tapered off in the 94-95 period, returning to pre-gang levels or below. Looking at assaults and burglaries, there was no difference between gang and non-adjacent neighborhoods, and they both showed general downward trends over time, apparently unaffected by the introduction of gangs.

So what conclusions can be drawn from this data? It would appear that gangs aren't involved in assaults or burglaries, though they also don't result in the protective effects that were hypothesized. Drug crimes, robberies, and gunshots all increased, but only briefly. What could be causing this? Is it a need for the gang to establish itself as a force in the community with a concentrated burst of crime? Or is it a result of increased police focus and refinement of tactics having a real effect on crime? Alternately, it could possibly just be citizen fatigue, with residents getting tired of constantly calling 911, or having little to show for it when they do. Other possibilities are that residents are being threatened, or that they may actually benefit from the increased economic activity of the drug trade. Ultimately, it looks like the selection theory is not supported, and that gang activity actually results in new crimes and criminals, and doesn't just round up the old ones.

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