Deterrent effects of police raids on crack houses: A randomized, controlled experiment

Sherman, Lawrence W.; Rogan, Dennis P.; Edwards, Timothy; Whipple, R.T.P.; Shreve, Dennis; Witcher, Daniel; Trimble, William; Velke, Robert; Blumberg, Mark S.; Beatty, A. M.; Bridgeforth, Carol A.

doi:10.1080/07418829500096281

Cited by 166 publications

(123 citation statements)

References 12 publications

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“…The deterministic models developed here suggest that the empirically observed reductions in crime that follow implementation of hotspot policing strategies (8,32,33) are not a statistical artifact but rather may reflect suppression of crime risk below some threshold level necessary to sustain a subcritical crime hotspot. Crime should remain suppressed in such situations even after the removal of law enforcement pressure, until such time as a significant cluster of crimes pushes the system towards instability.…”

Section: Discussionmentioning

confidence: 99%

Dissipation and displacement of hotspots in reaction-diffusion models of crime

Short

Brantingham²,

Bertozzi³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

200

140

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The mechanisms driving the nucleation, spread, and dissipation of crime hotspots are poorly understood. As a consequence, the ability of law enforcement agencies to use mapped crime patterns to design crime prevention strategies is severely hampered. We also lack robust expectations about how different policing interventions should impact crime. Here we present a mathematical framework based on reaction-diffusion partial differential equations for studying the dynamics of crime hotspots. The system of equations is based on empirical evidence for how offenders move and mix with potential victims or targets. Analysis shows that crime hotspots form when the enhanced risk of repeat crimes diffuses locally, but not so far as to bind distant crime together. Crime hotspots may form as either supercritical or subcritical bifurcations, the latter the result of large spikes in crime that override linearly stable, uniform crime distributions. Our mathematical methods show that subcritical crime hotspots may be permanently eradicated with police suppression, whereas supercritical hotspots are displaced following a characteristic spatial pattern. Our results thus provide a mechanistic explanation for recent failures to observe crime displacement in experimental field tests of hotspot policing.crime pattern formation | hotspot policing | mathematical modeling | nonlinearity | partial differential equations C rime is a ubiquitous feature of all modern cities, but not all neighborhoods are affected equally. In fact, serious crimes ranging from residential burglary to homicide are strongly patterned in time and space, forming crime "hotspots" (1-3). Studies show that policing actions directed at crime hotspots do lead to real reductions in offending and calls to the police for service (4, 5), while displacement of crime to adjacent settings may be less common than once thought (6-8). However, further gains in crime reduction are dependent upon gaining a quantitative understanding of the mechanisms that drive the emergence, spread, and dissipation of crime hotspots. Reaction-diffusion models, in which activators and inhibitors move, mix, and interact, provide a useful framework in which to investigate the formation of crime patterns and the impact of alternative policing strategies on crime hotspot stability. In this context, motivated offenders (activators) search their environment for suitable targets or victims (activators), which may also be mobile, following simple behavioral routines (9, 10). If an offender encounters a target in the absence of an effective security measure (inhibitor), then he is free to exploit that target. The immediate presence of security such as law enforcement is sufficient to deter that crime. Here we show that largescale spatial crime patterns, including the formation of stationary crime hotspots, are strongly dependent upon the local diffusion of risk, driven by offender mobility in the environment, coupled with the phenomena of repeat and near repeat victimization.

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Section: Discussionmentioning

confidence: 99%

Dissipation and displacement of hotspots in reaction-diffusion models of crime

Short

Brantingham²,

Bertozzi³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

200

140

View full text Add to dashboard Cite

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“…The model is centered around the concept of enhancing a community's capacity to identify and target its high-violence 20 neighborhoods and individuals. Prior research suggests that a small number of people, places, and guns (Sherman & Rogan, 1995) are disproportionally responsible for gun violence. By targeting scarce resources on these focal points, implementers can direct interventions toward those people, places, and guns that need the greatest attention.…”

Section: The Chicago Ceasefire Modelmentioning

confidence: 99%

Evaluation of the Phoenix TRUCE Project: A Replication of Chicago CeaseFire

Fox¹,

Katz

Choate

et al. 2014

Justice Quarterly

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The Phoenix TRUCE Project was modeled after the Chicago CeaseFire program. There have been relatively few process and impact evaluations on the model compared to the level of funding and attention the program has rendered. This paper presents findings related to the evaluation of the TRUCE project. We found that the program engaged in a strong media campaign, conducted conflict mediations, and identified high-risk individuals for case management. The program did not, however, establish a coordinated and collaborative relationship with the faith-based community or other community groups. Time-series analysis showed that program implementation corresponded to a significant decrease in overall levels of violence by more than 16 incidents on average per month, a decrease of 16 assaults on average per month, and resulted in a significant increase of 3.2 shootings on average per month, controlling for the comparison areas and the trends in the data.

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“…Therefore, there is an inherent lag between the information possessed by the criminals and that possessed by the police. The typical timescale for this lag in the real world may be on the order of weeks to months [22], which is enough time for new hotspots to emerge [28,5].…”

Section: -D Non-radially Symmetricmentioning

confidence: 99%

Nonlinear Patterns in Urban Crime: Hotspots, Bifurcations, and Suppression

Short¹,

Bertozzi²,

Brantingham³

2010

SIAM J. Appl. Dyn. Syst.

131

102

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Abstract. We present a weakly nonlinear analysis of our recently developed model for the formation of crime patterns. Using a perturbative approach, we find amplitude equations that govern the development of crime "hotspot" patterns in our system in both the 1D and radially symmetric 2D cases. In addition to the supercritical spots already shown to exist in our previous work, we prove here the existence of subcritical hotspots that arise via a subcritical pitchfork bifurcation in 1D and a transcritical bifurcation in 2D. We present numerical results that both validate our analytical findings and confirm the existence of these subcritical hotspots in the non-radially symmetric 2D case. Finally, we examine the differences between these two types of hotspots with regard to attempted hotspot suppression, referencing the varying levels of success such attempts have had in real world scenarios.

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Deterrent effects of police raids on crack houses: A randomized, controlled experiment

Cited by 166 publications

References 12 publications

Dissipation and displacement of hotspots in reaction-diffusion models of crime

Dissipation and displacement of hotspots in reaction-diffusion models of crime

Evaluation of the Phoenix TRUCE Project: A Replication of Chicago CeaseFire

Nonlinear Patterns in Urban Crime: Hotspots, Bifurcations, and Suppression

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