CAN HOT SPOTS POLICING REDUCE CRIME IN URBAN AREAS? AN AGENT‐BASED SIMULATION*

Over the past two decades, there has been a growing consensus among researchers that hot spots policing is an effective strategy to prevent crime. Although strong evidence exists that hot spots policing will reduce crime at hot spots without immediate spatial displacement, we know little about its possible jurisdictional or large‐area impacts. We cannot isolate such effects in previous experiments because they (appropriately) compare treatment and control hot spots within large urban communities, thus, confounding estimates of area‐wide impacts. An agent‐based model is used to estimate area‐wide impacts of hot spots policing on street robbery. We test two implementations of hot spots policing (representing different levels of resource allocation) in a simulated borough of a city, and we compare them with two control conditions, one model with constant random patrol and another with no police officers. Our models estimate the short‐ and long‐term impacts on large‐area robbery levels of these different schemes of policing resources. These experiments reveal statistically significant effects for hot spots policing beyond both a random patrol model and a landscape without police. These simulations suggest that wider application of hot spots policing can have significant impacts on overall levels of crime in urban areas.     

Hot spots policing and crime prevention: A systematic review of randomized controlled trials

Crime scholars and practitioners have argued that police actions should be focused on high-risk crime places rather than spread thinly across the urban landscape. This review examines five randomized controlled trials of the effects of concentrating police enforcement efforts on crime hot spots. The findings of these evaluations suggest that focused police actions can prevent crime and disorder in crime hot spots. A meta-analysis of the effect sizes from the five experiments reveals a statistically significant mean effect size for hot spots policing interventions; this suggests overall reductions in citizen calls for service in the treatment hot spots relative to the control hot spots. These studies also suggest that focused police actions at specific locations do not necessarily result in crime displacement. Although these evaluations reveal that these programs work in preventing crime, additional research is needed to unravel other important policy-relevant issues such as community reaction to focused police enforcement efforts.     

“Soft” policing at hot spots—do police community support officers work? A randomized controlled trial

Objectives

To determine whether crime-reduction effects of increased police patrols in hot spots are dependent on the “hard” threat of immediate physical arrest, or whether “soft” patrols by civilian (but uniformed) police staff with few arrest powers and no weapons can also reduce crime. We also sought to assess whether the number of discrete patrol visits to a hot spot was more or less important than the total minutes of police presence across all visits, and whether effects based on counts of crime would be consistent with effects on a Crime Harm Index outcome.

Methods

We randomly assigned 72 hot spots into 34 treatment units and 38 controls. Treatment consisted of increases in foot patrol by uniformed, unarmed, Police Community Support Officers (PCSOs) who carry no weapons and hold few arrest powers beyond those of ordinary citizens. GPS-trackers on every PCSO and Constable in the city yielded precise measurements of all patrol time in all hot spots. Standardized mean differences (Cohen’s d), OLS regression model, and Weighted Displacement Quotient are used to assess main effects, to model the interaction effect of GPS data with treatment, and to measure the diffusion-of-benefits of the intervention, respectively. Outcomes included counts of incidents as well as the Cambridge Crime Harm Index.

Results

As intended, patrol visits and minutes by Police Constables were equal across the treatment and control groups. The sole difference in policing between the treatments groups was in visits to the hot spots by PCSOs, in both the mean daily frequency of discrete visits (T?=?4.65, C?=?2.66; p?≤?.001) and total minutes across all visits (T?=?37.41, C?=?15.92; p?≤?.001), approximately two more ten-minute visits per day in treatment than in control. Main effect estimates suggest 39 % less crime by difference-in-difference analysis of reported crimes compared to control conditions, and 20 % reductions in emergency calls-for-service compared to controls. Crime in surrounding areas showed a diffusion of benefits rather than displacement for treatment hot spots compared to controls. A “Reiss’s Reward” effect was observed, with more proactive patrols predicting less crime across treatment hot spots, while more reactive PCSO time predicted more crime across control hot spots. Crime Harm Index estimates of the seriousness value of crime prevented ranged from 85 to 360 potential days of imprisonment in each treatment group hot spot (relative to controls) by a mean difference of 21 more minutes of PCSO patrol per day, for a potential return on investment of up to 26 to 1.

Conclusions

A crime reduction effect of extra patrols in hot spots is not conditional on “hard” police power. Even small differences in foot patrols showing the “soft power” of unarmed paraprofessionals, holding constant vehicular patrols by Police Constables, were causally linked to both lower counts of crimes and a substantially lower crime harm index score. Correlational evidence within the treatment group suggests that greater frequency of discrete PCSO visits may yield more crime reduction benefit than greater duration of those visits, but RCTs are needed for better evidence on this crucial issue.

     

THE PHILADELPHIA FOOT PATROL EXPERIMENT: A RANDOMIZED CONTROLLED TRIAL OF POLICE PATROL EFFECTIVENESS IN VIOLENT CRIME HOTSPOTS*

Originating with the Newark, NJ, foot patrol experiment, research has found police foot patrols improve community perception of the police and reduce fear of crime, but they are generally unable to reduce the incidence of crime. Previous tests of foot patrol have, however, suffered from statistical and measurement issues and have not fully explored the potential dynamics of deterrence within microspatial settings. In this article, we report on the efforts of more than 200 foot patrol officers during the summer of 2009 in Philadelphia. Geographic information systems (GIS) analysis was the basis for a randomized controlled trial of police effectiveness across 60 violent crime hotspots. The results identified a significant reduction in the level of treatment area violent crime after 12 weeks. A linear regression model with separate slopes fitted for treatment and control groups clarified the relationship even more. Even after accounting for natural regression to the mean, target areas in the top 40 percent on pretreatment violent crime counts had significantly less violent crime during the operational period. Target areas outperformed the control sites by 23 percent, resulting in a total net effect (once displacement was considered) of 53 violent crimes prevented. The results suggest that targeted foot patrols in violent crime hotspots can significantly reduce violent crime levels as long as a threshold level of violence exists initially. The findings contribute to a growing body of evidence on the contribution of hotspots and place‐based policing to the reduction of crime, and especially violent crime, which is a significant public health threat in the United States. We suggest that intensive foot patrol efforts in violent hotspots may achieve deterrence at a microspatial level, primarily by increasing the certainty of disruption, apprehension, and arrest. The theoretical and practical implications for violence reduction are discussed.     

Does police patrol in large areas prevent crime? Revisiting the Kansas City Preventive Patrol Experiment

Research Summary

The Kansas City Preventive Patrol Experiment (KCPPE) was seen by its developers to have produced “consistent evidence of the lack of effects of any consequence on crime,” a conclusion that was to have a strong impact on assumptions about police patrol for almost half a century. We identified the original official crime data from the KCPPE, and reanalyzed outcomes focusing on a comparison of the “proactive” versus “control” beats (“reactive beats” were criticized because of violations of treatment integrity); examining broad categories of crime (to increase statistical power); and using count regression models. Our findings are not unequivocal, but point to modest impacts of police patrol on crime in police beats.

Policy Implications

Our findings suggest that lessons drawn for half a century from the KCPPE need to be revisited. The KCPPE does not show that police patrol in large areas has no influence on crime, and this finding is consistent with several more recent studies. At the same time, we note that the effects of patrol in the KCPPE using our analysis strategy, and those found in other studies of preventive patrol in larger areas, are about half that found in hot spots policing studies. This suggests that police agencies ideally should invest in focused hot spots policing initiatives. However, absent an ability to manage such initiatives, or the crime analysis capabilities to identify crime hot spots routinely, simpler preventive patrol schemes to utilize uncommitted patrol time can be seen as potentially effective in preventing crime.     

The efficacy of foot patrol in violent places

Objectives

This study examines the effectiveness of foot patrol in violent micro-places. A large urban police department deployed foot patrol in micro-places (hot spots) for a period of 90 days for two shifts each day. Our objective is to determine whether this activity impacted violent crime in these hot spots and whether spatial displacement of crime occurred.

Methods

Eight eligible foot beat locations were set by examining crime rates for previous years in order to identify micro-places of high criminal activity. We employed a quasi-experimental design comparing the four treatment to the four control areas, estimating panel-specific autoregressive models for 30 weeks prior to and 40 weeks after the treatment.

Results

Time series models revealed statistically significant reductions in violent crime in the micro-places receiving foot patrol treatment, while no such reductions were observed in the control areas. The deterrent effect, however, was short and dissipated quickly. Control areas did not experience any crime prevention benefit during this time period. No evidence of crime displacement to spatially contiguous areas was detected.

Conclusions

This contributes to the growing body of knowledge that focused police strategies within hot spots impact violent crime. Specifically, the implementation of foot patrol in high crime hot spots led to measurable reductions in aggravated assaults and robberies, without displacing crime to contiguous areas.

     

A randomized test of initial and residual deterrence from directed patrols and use of license plate readers at crime hot spots

Objectives

To test the effects of short-term police patrol operations using license plate readers (LPRs) on crime and disorder at crime hot spots in Mesa, Arizona.

Methods

The study employed a randomized experimental design. For 15 successive 2-week periods, a four-officer squad conducted short daily operations to detect stolen and other vehicles of interest at randomly selected hot spot road segments at varying times of day. Based on random assignment, the unit operated with LPRs on some routes and conducted extensive manual checks of license plates on others. Using random effects panel models, we examined the impact of these operations on violent, property, drug, disorder, and auto theft offenses as measured by calls for service.

Results

Compared to control conditions with standard patrol strategies, the LPR locations had reductions in calls for drug offenses that lasted for at least several weeks beyond the intervention, while the non-LPR, manual check locations exhibited briefer reductions in calls regarding person offenses and auto theft. There were also indications of crime displacement associated with some offenses, particularly drug offenses.

Conclusions

The findings suggest that use of LPRs can reduce certain types of offenses at hot spots and that rotation of short-term LPR operations across hot spots may be an effective way for police agencies to employ small numbers of LPR devices. More generally, the results also provide some support for Sherman’s (1990) crackdown theory, which suggests that police can improve their effectiveness in preventing crime through frequent rotation of short-term crackdowns across targets, as it applies to hot spot policing.     

DOES WHAT POLICE DO AT HOT SPOTS MATTER? THE PHILADELPHIA POLICING TACTICS EXPERIMENT*

Policing tactics that are proactive, focused on small places or groups of people in small places, and tailor specific solutions to problems using careful analysis of local conditions seem to be effective at reducing violent crime. But which tactics are most effective when applied at hot spots remains unknown. This article documents the design and implementation of a randomized controlled field experiment to test three policing tactics applied to small, high‐crime places: 1) foot patrol, 2) problem‐oriented policing, and 3) offender‐focused policing. A total of 81 experimental places were identified from the highest violent crime areas in Philadelphia (27 areas were judged amenable to each policing tactic). Within each group of 27 areas, 20 places were randomly assigned to receive treatment and 7 places acted as controls. Offender‐focused sites experienced a 42 percent reduction in all violent crime and a 50 percent reduction in violent felonies compared with their control places. Problem‐oriented policing and foot patrol did not significantly reduce violent crime or violent felonies. Potential explanations of these findings are discussed in the contexts of dosage, implementation, and hot spot stability over time.     

Explaining Dosage Diffusion During Hot Spot Patrols: An Application of Optimal Foraging Theory to Police Officer Behavior

Drawing from the concepts of optimal foraging theory, this paper presents and tests the assumptions of a foraging theory of police behavior during hot spots patrols. The theory explains why, over time, officers involved in hot spots policing interventions would leave the hot spots they are assigned to police and begin working within other locations. We test what factors influence the amounts of activity that officers undertake outside of their assigned hot spots and at nearby streets using data gathered as part of the Philadelphia Foot Patrol Experiment. Officers performed more activity outside of their beats as the experiment progressed. Several theoretically relevant variables predict the level of activity that officers perform outside their beats, including the size of the target area and the amounts of crime occurring within and outside of the target area. “Dosage diffusion” might be one reason why hot spot interventions have diminishing effects over time. From an optimal foraging theory perspective, hot spots requiring police officers to constrain their actions to pre-defined areas can be perceived as counter-intuitive by the officers, especially over extended periods of time. The results of this study support the suggestion that hot spots patrols should be short-term and randomly rotated across hot spots.     

How Much Time Should the Police Spend at Crime Hot Spots? Answers from a Police Agency Directed Randomized Field Trial in Sacramento,California

Hot spots policing has been shown to be an effective strategy for reducing crime across a number of rigorous evaluations, but despite this strong body of research, there still exist gaps in our knowledge of how officers can best respond to hot spots. We report on a randomized experiment in Sacramento, California that begins to address these gaps by testing the recommendation from prior research that police officers randomly rotate between hot spots, spending about 15?min patrolling in each. Our results suggest significant overall declines in both calls for service and crime incidents in the treatment hot spots relative to the controls. Additionally, the study was carried out primarily by the Sacramento Police Department without any outside funding. In an era of limited economic resources for policing, this experiment suggests a model by which police agencies can take ownership of science and oversee the implementation and evaluation of evidence-based interventions.     

Identifying changes in spatial patterns from police interventions: the importance of multiple methods of analysis

The policing initiative of foot patrol was implemented to reduce crime and disorder as well as benefit the relationship between the community and the police in the community of Lower Lonsdale, North Vancouver, British Columbia. In this paper, police incident data are analyzed to evaluate the impact of police foot patrol on the hot spots of crime in this community. Specifically, two spatial analysis techniques (kernel density estimation and local Moran’s I) are used to show how the nuances of changes in spatial crime patterns can emerge when multiple methods of analysis are used.     

A randomized controlled trial of different policing strategies at hot spots of violent crime

Focusing police efforts on “hot spots” has gained acceptance among researchers and practitioners. However, little rigorous evidence exists on the comparative effectiveness of different hot spots strategies. To address this gap, we randomly assigned 83 hot spots of violence in Jacksonville, Florida, to receive either a problem-oriented policing (POP) strategy, directed-saturation patrol, or a control condition for 90 days. We then examined crime in these areas during the intervention period and a 90-day post-intervention period. In sum, the use of POP was associated with a 33% reduction in “street violence” during the 90 days following the intervention. While not statistically significant, we also observed that POP was associated with other non-trivial reductions in violence and property crime during the post-intervention period. In contrast, we did not detect statistically significant crime reductions for the directed-saturation patrol group, though there were non-significant declines in crime in these areas during the intervention period. Tests for displacement or a diffusion of benefits provided indications that violence was displaced to areas near the POP locations, though some patterns in the data suggest this may have been due to the effects of POP on crime reporting by citizens in nearby areas. We conclude by discussing the study’s limitations and the implications of the findings for efforts to refine hot spots policing.     

The Impact of Hot Spots Policing on Collective Efficacy: Findings from a Randomized Field Trial

In disadvantaged neighborhoods, prior research has found reduced social cohesion and less willingness among residents to address disruptive behaviors and violations of social norms. This deficiency is commonly associated with higher levels of disorder and crime. Therefore, recent scholarship has begun to consider whether police can help foster collective efficacy, especially in places struggling with serious crime problems. Early results are somewhat mixed. Yet the cooperation hypothesis asserts that when neighborhood residents see police as a more viable and reliable resource, residents will be emboldened to exert informal social control to address problems. Over the last two decades, hot spots policing has been recognized as an effective method to reduce crime. At the same time, there have been few rigorous studies of whether this approach impacts collective efficacy at hot spots. To investigate this question, we conducted an experiment in 71 crime hot spots, comparing a collaborative problem solving versus a directed patrol (police presence) approach versus standard policing practices. Over time, a substantial increase in police presence did appear to promote modest improvements in collective efficacy. We attribute this finding to the cooperation hypothesis.     

DETERRENCE,CRIMINAL OPPORTUNITIES,AND POLICE

In this article, we join three distinct literatures on crime control—the deterrence literature, the policing literature as it relates to crime control, and the environmental and opportunity perspectives literature. Based on empirical findings and theory from these literatures, we pose a mathematical model of the distribution of criminal opportunities and offender decision making on which of those opportunities to victimize. Criminal opportunities are characterized in terms of the risk of apprehension that attends their victimization. In developing this model, our primary focus is on how police might affect the distribution of criminal opportunities that are attractive to would‐be offenders. The theoretical model we pose, however, is generalizable to explain how changes in other relevant target characteristics, such as potential gain, could affect target attractiveness. We demonstrate that the model has important implications for the efficiency and effectiveness of police deployment strategies such as hot spots policing, random patrol, and problem‐oriented policing. The theoretical structure also makes clear why the clearance rate is a fundamentally flawed metric of police performance. Future research directions suggested by the theoretical model are discussed.     

Just enough police presence: Reducing crime and disorderly behavior by optimizing patrol time in crime hot spots

Using observational data collected as part of a one-year preventive patrol study in Minneapolis, this investigation employs survival models to test hypotheses about the effects of specific instances of police patrol presence at high-crime locations on the time until the next occurrence of criminal or disorderly behavior at these locations. The results show that patrol stops must reach a threshold dosage of about 10 minutes in order to generate significantly longer survival times without disorder — i.e., greater residual deterrence — than that generated by driving through a hot spot. The optimal length for patrol stops appears to be 11 to 15 minutes. After that point, continued police presence brings diminishing returns. The theoretical and policy implications of these results are discussed.     

Foot Patrol in Violent Crime Hot Spots: The Longitudinal Impact of Deterrence and Posttreatment Effects of Displacement

This study revisited the Philadelphia Foot Patrol Experiment and explored the longitudinal deterrent effects of foot patrol in violent crime hot spots using Sherman's (1990) concepts of initial and residual deterrence decay as a theoretical framework. It also explored whether the displacement uncovered during the initial evaluation decayed after the experiment ended. Multilevel growth curve models revealed that beats staffed for 22 weeks had a decaying deterrent effect during the course of the experiment, whereas those staffed for 12 weeks did not. None of the beats had residual deterrence effects relative to the control areas. The displacement uncovered had decayed during the 3 months after the experiment, and it is theoretically plausible that previously displaced offenders returned to the original target areas causing inverse displacement. These results are discussed in the context of Durlauf and Nagin's (2011) recent proposal that prison sentences should be shortened, mandatory minimum statutes repealed, and the cost savings generated by these policy changes shifted into policing budgets to convey more effectively the certainty of detection. It is concluded that if Durlauf and Nagin's proposal is to succeed, then more holistic policing strategies would likely be necessary. Foot patrol as a specific policing tactic seems to fit nicely into a variety of policing paradigms, and suggestions for incorporating them to move beyond strictly enforcement‐based responses are presented.     

Offender-focused police intervention in residential burglary and theft from vehicle hot spots: a partially blocked randomized control trial

Objectives

To test an offender-focused police intervention in residential burglary and residential theft from vehicle hot spots and its effect on crime, arrests, and offender recidivism. The intervention was prevention-focused, in which detectives contacted offenders and their families at their homes to discourage criminal activity.

Methods

The study was a partially blocked, randomized controlled field experiment in 24 treatment and 24 control hot spots in one suburban city with average crime levels. Negative binomial and ordinary least squares (OLS) regression were used to test the effect of the presence of intervention and its dosage on crime and offender recidivism, and examination of average and standardized treatment effects were conducted.

Results

The analyses of the hot spot impact measures did not reveal significant results to indicate that the treatment had an effect on crime or arrest counts, or on repeat arrests of the targeted or non-targeted offenders living in the hot spots. However, the relationships, while not significant, were in a promising direction.

Conclusions

The collective findings from all four impact measures suggest that the intervention may have had some influence on the targeted offenders, as well as in the treatment hot spots. So, while the experimental results did not show an impact, they are promising. Limitations include large hot spots, the low case number, low base rates, and inadequate impact measures. Suggestions are provided for police agencies and researchers for implementing preventive offender-focused strategies and conducting studies in suburban cities.

     

Optimal patrol routes: interdicting and pursuing rhino poachers

Interdiction patrolling (also known as hot spots policing) is a proactive police operation that depends on good planning. And the pursuit of fleeing suspects is a challenging operation that all police forces engage in on a regular basis. We give software tools that improve the effectiveness of both. We demonstrate the effectiveness of our tools by applying them to the case of rhino poaching in wildlife reserves. An interdiction patrol pre-emptively seeks out poaching parties within a reserve. Upon picking up the trail of a poaching party, a pursuit team needs a pursuit strategy that optimizes their chances of an interception. Our interdiction patrol route tool identifies optimal interdiction patrol routes to walk. This tool is based on a Stackelberg game and represents different types of poachers and their utilities. These utilities are updated (learned) each time new information on poaching party routes is added to the database. Our second tool provides a real-time sequence of team member moves that maximizes the team’s chances of apprehending a pursued party. We show that our tools perform well when applied to simulated and real data.     

DRIVING WHILE BLACK: BIAS PROCESSES AND RACIAL DISPARITY IN POLICE STOPS*

We estimate the degree of racial disparity in police vehicular stops separately for local and state police in North Carolina in the year 2000. We introduce four mechanisms that might produce racial disparities in police stops—racial profiling, race sensitive police deployment, cognitive bias and stereotyping, and prejudice. We then model the relative odds of police vehicle stops as a function of race, driving behavior, and other demographic statuses separately by police organization type, with controls for omitted variable bias at both the driver and spatial level. We find only weak evidence of racial disparity in stops by officers of the state highway patrol but stronger evidence in those made by local police officers.