Christopher S. Koper

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.

Receptivity to Research in Policing

Evidence-based policing—using research and scientific processes to inform police decisions—is a complex approach to policing that involves various challenges. One primary difficulty is how research can be translated into digestible and familiar forms for practitioners. A central part of successful translation is the receptivity of decisionmakers to research as well as how research is presented and packaged to increase receptivity. In this article we first discuss the complexity of evidence-based policing, highlighting the much-lamented gap between research and practice. We review research from other disciplines and also in policing about what contributes to research being better received and used by practitioners. We then describe our own receptivity survey, offering preliminary findings about the receptivity of officers to research, researchers, and tactics influenced by research. Finally, we conclude with examples of the types of efforts practitioners and researchers can engage in that might improve receptivity to research. Specifically, we discuss the Evidence-Based Policing Matrix as a research translation tool, as well as multiple demonstrations conducted by the authors that focus on institutionalizing the use of research into daily police activities.

Race and Sex Differences in the Prediction of Drug Use.

Efforts to prevent adolescent substance abuse often direct prevention efforts at known correlates of substance use. The applicability to minority populations of risk factors uncovered for the general population has been questioned, and the development of different programs targeting the risk factors most salient for different groups has been recommended. Such differentiated programming requires a more precise understanding of ethnic differences in the predictors of substance use than is now available. This article assesses these differences using data from 981 Black and White male and female adolescents and latent variable structural equations techniques. No group differences were observed in the prediction of past year variety of drug use for 9 of the 12 risk factors examined. The predictive validity was higher for Whites than for Blacks for 3 risk factors. The prediction of frequency of use was weaker for Black women than for other groups. The low predictive validity observed for Black women is most likely due to the extremely low level of use among this group. The study concludes that the measures of risk factors predict substance use for all groups examined but that extremely rare behaviors are not well predicted.

Combating Vehicle Theft in Arizona: A Randomized Experiment With License Plate Recognition Technology

This article focuses on a relatively new innovation for use by law enforcement, license plate recognition (LPR) systems, in fighting auto theft. While it is a promising technology, there has not been much research on the effectiveness of LPR systems. The authors conducted a randomized experiment to study the effects of LPR devices on auto theft. The authors found that the LPR is achieving its most basic purpose of increasing the number of plates scanned by officers (8 times greater) compared to manual plate checking. Further, when compared to manual checking, the LPR was associated with more “hits” (i.e., positive scans) for auto theft and stolen plates, more arrests for stolen vehicles, and more stolen vehicle recoveries. Unexpectedly, the authors found that manual plate checking by a special auto theft unit (but not LPR scanning by the same unit) was associated with less auto theft 2 weeks after the intervention (based on both police crime reports and calls for police service) than the control group (regular nonspecialized patrol without LPR). Finally, the authors found no evidence of crime displacement occurring from their targeted routes to adjacent areas for any of their models. This study provides evidence that LPR use can achieve demonstrable benefits in combating auto theft (i.e., more plates scanned, “hits,” arrests and recoveries with LPR). These results are impressive for the field of auto theft where so little research tested interventions exist. Future work will involve developing strategies that maintains the documented benefits of LPR use by a specialized unit, but also achieve the benefits associated with manual checking by a specialized unit.

The effects of local immigration enforcement on crime and disorder: a case study of Prince William County, Virginia

Research Summary This study evaluates a local immigration enforcement policy implemented in Prince William County, Virginia, in 2008. In addition to joining the federal 287(g) program, the County adopted a policy that initially required officers to check the immigration status of people they detained, but the policy was later amended to require immigration checks only for arrestees. Using a pre–post, quasi-experimental design, we examined the policys impacts on crime reports and calls for service in Prince William County and compared the Countys crime trends with those of nearby localities. We also analyzed postpolicy trends in arrests of illegal immigrants, survey reports of crime victimization and reporting among County residents, and survey reports of police views on crime and disorder in the County. Although the policy did not affect most forms of crime in Prince William County (including robberies, property crimes, drug offenses, disorderly behaviors, and drunk driving violations), aggravated assaults declined 27% after the announcement of the original policy in July 2007. However, this initial version of the policy also seemed to harm police relations with the immigrant community, among other problems. Policy Implications As part of the wider debate on illegal immigration in the United States, local police are becoming more heavily involved in immigration enforcement in part as a result of a growing number of state laws and local ordinances directing police to engage in these efforts. The impacts of local immigration enforcement efforts have received very little study to date. Consistent with research on immigration and crime generally, this study suggests that public concern regarding crime by illegal immigrants is perhaps overstated and that expanded local immigration enforcement efforts will have limited impacts on crime. More aggressive immigration enforcement policies may reduce some types of crime, but they also may harm police relations with immigrant communities and impose other costs on local police. Further policy experimentation and research may help local communities to develop balanced approaches that focus on criminal violators and target specific crime problems in immigrant communities without the potentially negative consequences of more widespread crackdowns on illegal immigration.

Impact of handgun types on gun assault outcomes: a comparison of gun assaults involving semiautomatic pistols and revolvers

Objective: To examine whether gun assaults committed with semiautomatic pistols are more injurious and lethal than those committed with revolvers. Setting: Jersey City, New Jersey from 1992 through 1996. Methods: Using police records on fatal and non-fatal handgun assaults, t tests and χ2 tests were employed to determine if attacks with pistols result in more shots fired than those with revolvers, leading to more gunshot victims and more severely wounded victims. Results: More shots were fired in attacks with pistols (average = 3.2 to 3.7) than in attacks with revolvers (average = 2.3 to 2.6). Although pistol use was unrelated to the probability that an incident resulted in any injury or death, it was associated with a 15% increase in the number of wounded victims in those cases in which people were shot (1.15 per pistol case, 1.0 per revolver case), implying that the total number of gunshot victims may have been 9.4% lower had pistols not been used in any attacks. Pistol use was not related to the number of wounds per gunshot victim. Conclusions: The findings provide limited evidence that recent growth in the production and use of pistols has contributed to higher levels of gunshot victimizations. However, available data did not permit an assessment of whether the associations between gun types and assault outcomes are mediated by characteristics of incidents and actors.

Assessing the Practice of Hot Spots Policing Survey Results From a National Convenience Sample of Local Police Agencies

This study examined the practice of hot spots policing as reported by a convenience sample of predominantly large municipal police agencies. Police commonly defined hot spots in terms of micro places as well as larger areas, and they emphasized short-term identification and responses to hot spots. Respondents identified problem analysis/solving, targeting offenders, and directed patrol as the most common and effective strategies for hot spots, but there was wide variation in their views of the most effective strategies for different types of hot spots. Current practices could arguably be improved through more a precise geographic focus, a greater emphasis on chronic hot spots and their criminogenic features, and further research to determine optimal strategies, dosages, and proactive uses of hot spots policing.

Race and Sex Differences in the Measurement of Risk for Drug Use

The study uses data from 2018 Black and White males and females and latent-variable structural equations techniques to examine group differences in the measurement of risk factors for substance use. First, the equivalence of measurement models for four demographic groups is examined separately for 12 risk factors and 2 measures of substance use. Then these 14 measures are correlated with five external criteria to assess measurement validity. Results imply that one measurement model fits the data for 11 of the 12 risk factors. For one risk factor (Peer Drug Modeling) and the two drug use scales, observed group differences in the factor loadings stemmed from differences in the distributions of a few drug-related items which were infrequently endorsed, especially by Black females. No meaningful group difference in the validity coefficients relating the scales to external criteria were observed. The results are optimistic for the study of race and sex differences in the correlates of substance use. But research on group differences in the prediction of rare behaviors should examine group differences in distributions which may effect measurement differently for different groups.

Understanding the Limits of Technology’s Impact on Police Effectiveness:

Technology has become a major source of expenditure and innovation in law enforcement and is assumed to hold great potential for enhancing police work. But does technology achieve these expectations? The current state of research on technology in policing is unclear about the links between technologies and outcomes such as work efficiencies, effectiveness in crime control, or improved police–community relationships. In this article, we present findings from a mixed-methods, multiagency study that examines factors that may mediate the connection between technology adoption and outcome effectiveness in policing. We find that police view technology through technological and organizational frames determined by traditional and reactive policing approaches. These frames may limit technology’s potential in the current reform era and cause unintended consequences.

Homicide and geographic access to gun dealers in the United States

BackgroundFirearms are the most commonly used weapon to commit homicide in the U.S. Virtually all firearms enter the public marketplace through a federal firearms licensee (FFL): a store or individual licensed by the federal government to sell firearms. Whether FFLs contribute to gun-related homicide in areas where they are located, in which case FFLs may be a homicide risk factor that can be modified, is not known.MethodsAnnual county-level data (1993–1999) on gun homicide rates and rates of FFLs per capita were analyzed using negative binomial regression controlling for socio-demographic characteristics. Models were run to evaluate whether the relation between rates of FFLs and rates of gun homicide varied over the study period and across counties according to their level of urbanism (defined by four groupings, as below). Also, rates of FFLs were compared against FS/S – which is the proportion of suicides committed by firearm and is thought to be a good proxy for firearm availability in a region – to help evaluate how well the FFL variable is serving as a way to proxy firearm availability in each of the county types of interest.ResultsIn major cities, gun homicide rates were higher where FFLs were more prevalent (rate ratio [RR] = 1.70, 95% CI 1.03–2.81). This association increased (p < 0.01) from 1993 (RR = 1.69) to 1999 (RR = 12.72), due likely to federal reforms that eliminated low-volume dealers, making FFL prevalence a more accurate exposure measure over time. No association was found in small towns. In other cities and in suburbs, gun homicide rates were significantly lower where FFLs were more prevalent, with associations that did not change over the years of the study period. FFL prevalence was correlated strongly (positively) with FS/S in major cities only, suggesting that the findings for how FFL prevalence relates to gun homicide may be valid for the findings pertaining to major cities but not to counties of other types.ConclusionModification of FFLs through federal, state, and local regulation may be a feasible intervention to reduce gun homicide in major cities.