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.     

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.     

Situational deterrence and claim padding: results from a randomized field experiment

While it is generally argued that threats of legal sanctions are more effective with offenders involved in economic crimes than with delinquents committing more conventional crimes, such an affirmation rests on weak empirical evidence. Also, most studies supporting this proposition were conducted with non-experimental designs, thus, undermining the interval validity of the results. On the other hand, studies base their predictions on individual factors and do not incorporate contextual factors. To overcome those limitations, a randomized field experiment was implemented in four insurance companies to incorporate contextual factors into the dynamics of deterrence. This study assessed the effect of a written threat (a deterrent letter reminding insured persons of the punishment for insurance fraud) on claim padding behaviours of insured persons filing claims for residential theft. A deterrent-letter project was implemented in four insurance companies, with claims randomly assigned to the experimental or the control group. Cases belonging to the control group were managed as usual, while individuals in the experimental group received the written threat. The experimental design made sure that the deterrent stimulus was exactly delivered to the insured persons when they had the opportunity to exaggerate the value of their claims. Findings demonstrate that claimants in the experimental group were less likely to pad their claims than were those in the control group. The letter was effective, regardless of the means of delivery. In conclusion, the administration of a written threat at the moment of criminal opportunity appears to be an effective strategy for preventing economic crimes.

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.     

The impact of TASERs on police use-of-force decisions: Findings from a randomized field-training experiment

This paper presents findings from a randomized field-training experiment designed to study the impact TASERs on police officers’ use-of-force decisions. Officers were randomly assigned to either a treatment group (with TASERs) or a control group (without TASERs) and then participated in training scenarios involving different levels of suspect resistance. The study investigates whether and to what extent officers armed with the TASER use it as an alternative to other types of less-lethal force (e.g., empty hands, pepper spray, and the baton) and the firearm, controlling for the level of suspect resistance. The findings indicate that officers who were armed with the TASER were significantly less likely to deploy pepper spray and the baton in response to aggressive physical resistance. Additionally, the results show that officers equipped with the TASER were less likely to discharge their firearm when confronted with suspect resistance that was potentially lethal. No differences in police behavior occurred in response to passive suspect resistance.     

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.     

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.

     

License plate reader (LPR) police patrols in crime hot spots: an experimental evaluation in two adjacent jurisdictions

Objectives  

This randomized controlled experiment tests whether license plate readers (LPR) deter crime generally, and automobile crime more specifically in crime hot spots. The limited intervention tested here reflects one current likely use of LPR at the time of this publication.     

The mobilization of computerized crime mapping: a randomized controlled trial

Journal of Experimental Criminology - To develop and evaluate the effectiveness of a decentralized, smartphone-based crime mapping and analysis tool designed for law enforcement officers working in...     

The DNA field experiment: a randomized trial of the cost-effectiveness of using DNA to solve property crimes

We report the results of a prospective, randomized study of the impact and cost-effectiveness of DNA evidence in investigating property crimes, mainly residential burglary. Biological evidence was collected at up to 500 crime scenes in five U.S. cities between 2005 and 2007, and cases were randomly assigned to the treatment and control groups in equal numbers. DNA processing was added to traditional investigation in the treatment group. A suspect was identified in 31% of treatment cases and 13% of control cases. A suspect was arrested in 22% of treatment cases and 10% of control cases. Across the five sites, each additional arrest—an arrest that would not have occurred without DNA processing—cost slightly more than US14,000. In the most cost-effective sites, an additional arrest cost less than US14,000. In the most cost-effective sites, an additional arrest cost less than US4,000. Expanding the use of DNA as an investigative tool has profound implications. Since DNA-led investigations are more costly than business-as-usual, substantial investments will be required to expand the capacity of crime laboratories, police, and prosecutors to use this investigative tool efficiently. In time, such a change may also impact the types of crimes of cases processed in the criminal justice system.     

Context manipulation in police interviews: a field experiment

Journal of Experimental Criminology - Recent writing and research on interrogation has highlighted the potential importance of the physical context in which the interview takes place. Whereas...     

Lessons from a field experiment involving involuntary subjects 3,000 miles away

Objectives

Describe the challenges involved in conducting field experiments that entail a long distance between the research team and the research site.

Methods

A summary of the lessons learned from the field experiment of Hawaii??s Opportunity Probation with Enforcement (HOPE).

Results

Pre-trial planning is especially important when the research team is a long distance from the research site. A good communication strategy helps educate practitioners on the merits of conservative design choices, such as intent-to-treat, and helps to signal the importance of the study and therefore of maintaining the condition assignments and delivering the intervention with fidelity.

Conclusions

Distance creates additional challenges for the research team. These challenges make it even more essential to exploit assets at the research site. Distance creates more uncertainty, which makes pre-planning even more important, but it is expensive. Criminal-justice funding agencies?? support for exploratory studies as precursors to full-blown trials would improve the quality of experimental criminal-justice research.     

Anti-theft procedures and fixtures: a randomized controlled trial of two situational crime prevention measures

Objectives  

This study was designed to test two problem-focused situational crime prevention treatments (protective display fixtures and special high-loss product handling procedures) on loss and sales levels of a perennial ‘hot product’ (premium shaving blade replacement packs).     

Adolescent Family Violence: Findings from a Group-Based Analysis

Journal of Family Violence - Current understanding of adolescent family violence (AFV) is fragmented, with research describing offenders and offending at the aggregate level or exploring different...     

Cost matters: a randomized experiment comparing recidivism between two styles of prisons

This study drew on a cost–benefit method to compare recidivism between two groups of inmates. Subjects were randomly assigned to serve a 6-month ‘early release’ term in one of two prisons which diverged dramatically in terms of structure, freedom, and staff–inmate interaction style (boot camp versus traditional prison). The study was motivated, in part, by the state of Maryland’s asking whether the ‘extra’ cost of running an early release program at the boot camp rather than a traditional prison was justified. Cost–benefit tools were employed, not only because they addressed this specific question, but also because they provided a platform for describing differences both in the amount and the quality (harm) of recidivism associated with facility assignment. Two themes are emphasized in this paper. First, even without consideration of differences in post-release impact, the boot camp cost less to run per inmate. This may be an important observation for policy makers now wrestling with budget declines and potential cuts; they should not assume that programs which offer more services are necessarily more expensive to operate than alternatives offering less. Second, the boot camp generated substantially less recidivism-harm relative to the traditional prison. This finding held across numerous sensitivity analyses standard to the field, as well as new approaches presented here.     

Exploring gender differences in dating violence/harassment prevention programming in middle schools: results from a randomized experiment

In this study, we randomly assigned 123 sixth and seventh grade classrooms from seven middle schools in the greater Cleveland area to one of two five-session curricula addressing gender violence/sexual harassment (GV/SH) or to a no-treatment control group. A baseline survey and two follow-up surveys were administered immediately after the treatment (Wave 2) and about six months post-treatment (Wave 3). In an earlier paper, we demonstrated the effectiveness of two approaches to youth GV/SH prevention programming (a fact-based, law and justice curriculum and an interaction-based curriculum). In this paper, we explored whether these largely positive findings remain for both girls and boys, including whether girls experience higher levels of GV/SH than boys. Most of our statistical models proved to be non-statistically significant. However, in 2 of our 48 victimization/perpetration (any violence, sexual violence and non-sexual violence) models (across two post-intervention follow-up points), we observed that the interventions reduced peer (male or female, non-dating partner) sexual violence victimization and reduced peer perpetration, but another outcome model indicated that the interventions increased dating perpetration. These mixed findings will need to be explored further in future research. Regarding our primary research question, we observed no statistically significant differences for the treatment multiplied by gender interaction terms for any of the perpetration or victimization outcome models, suggesting that the treatment had similar effects on girls and boys. However, we did observe that boys are more involved in violence than girls: both as victims and perpetrators. Boys experienced significantly more of three types of victimization from peers and dating partners compared to what girls experienced at the hands of their peers and dating partners. As perpetrators, boys committed more sexual victimization against peers (immediately post-intervention only) and more sexual victimization against dating partners than girls. The implications of these results are discussed.