The Deterrent Effects of Police Patrol Presence On Criminal and Disorderly Behavior at High Crime Locations
The Deterrent Effects of Police Patrol Presence On Criminal and Disorderly Behavior at High Crime Locations
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Date
1992
Authors
Koper, Christopher Sean
Advisor
Sherman, Lawrence W.
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Abstract
This paper tests the deterrent ( or displacement) effects of preventive
patrol upon criminal and non-criminal disorderly behaviors at high-crime
locations ("hot spots") using observational data collected during a preventive
patrol experiment in Minneapolis from December 1988 to November 1989.
The analyses reveal that the immediate presence of uniformed police directly
reduces the outbreak of disorderly conduct at hot spots, but this effect is
contingent upon raising the overall level of proactive presences at hot spots.
Increasing patrol levels at hot spots also produces residual deterrence which
decreases disorder during times when police are not present at these
locations. Such residual decreases in disorder are larger than the direct
deterrent effects of police presence when patrol is at normal levels. Further,
direct and residual deterrence generated by patrol are stronger for criminal
acts than for a combined measure of criminal and non-criminal disorderly
behaviors.
The analyses employed survival models to estimate the effects of specific
instances of patrol presence upon the time to the first disorder (criminal or
non-criminal) after police depart from a hot spot. Using presences up to 20
minutes in length, these models reveal that longer presences increase survival
time, thus enhancing residual deterrence. However, there is evidence this
effect decreases after presences pass about 14 minutes in duration. Moreover,
stops must be about 10 minutes in length in order to produce significantly
better survival times than those produced by driving through a hot spot. The
theoretical and policy implications of these results are discussed.