What Has Been Learned?
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While broad support for the pulling-levers approach may be justified
for many reasons, the committee found modest scientific evidence that
demonstrates whether these types of targeted policing programs can effectively
lower crime and violence. Clearly, there was pronounced and important
change in the youth homicide rate in Boston over the period of the
intervention, some of which was arguably due to Operation Ceasefire,
some due to secular changes in youth homicide, and some due to other (and
perhaps unknown) factors. The particular effects of this intervention, however,
are unknown. Furthermore, in the committee’s view, the existing data
and methods make it difficult to assess how Operation Ceasefire and other
similar policing programs affect crime. Researchers cannot hope to credibly
control for the many confounders that influence violence and crime using
simple time-series comparisons. With similar policing programs being
adopted in a number of other areas, there may be opportunities to combine
data from these sites to provide more persuasive estimates. Invariably,
however, researchers will be confronted with the fact that the programs
were not randomly adopted, the trends in violence are influenced by a
multitude of factors, and the dynamics of crime and violence are highly
complex.
The lack of research on this potentially important intervention is an
important shortcoming in the body of knowledge on firearms injury interventions.
These programs are widely viewed as effective, but in fact knowledge
of how, if at all, they reduce youth crime is limited. Without a much
stronger research base, the benefits and harms of these policing interventions
remain largely unknown. The committee recommends that a sustained
and systematic research program should be conducted to assess the
effect of targeted policing aimed at high-risk offenders. Additional insights
might be gained by using observational data from different applications,
especially if combined with thoughtful behavioral models of policing and
crime. An alternative means of assessing the impact of these types of targeted
policing interventions would be to run randomized experiments, similar
in spirit to those described above. Using this framework, one might hope
to disentangle the effects of the various levers and more generally assess the
effectiveness of these targeted policing programs.
10McGarrell and Chermak (2003) recently completed an unpublished study of the Indianapolis
pulling-levers intervention. Using time-series analyses, they found a 42 percent reduction
in homicides associated with the implementation of the intervention and found that
homicides were less likely to involve firearms, groups, and drugs.