Elizabeth R. Groff

Mapping an Opportunity Surface of Residential Burglary

The use of geographic information systems (GIS) to understand spatial patterns of crime and criminal behavior has become more prevalent in recent years, but with a few exceptions these analyses fall short of serving as predictive tools. The recent introduction of user-friendly, raster-based mapping software, designed primarily for environmental and planning purposes, offers new tools for examining and predicting crime and criminal behavior. By applying opportunity theories to the crime of residential burglary, this article examines the utility of raster-based mapping software for predicting desirable and undesirable locations of burglaries, as well as likely locations for crime displacement or diffusion. The findings reveal that the model holds promise for serving these prediction purposes.

Where the Action Is at Places: Examining Spatio-Temporal Patterns of Juvenile Crime at Places Using Trajectory Analysis and GIS

“Crime Places” have recently emerged as an important focus of crime prevention theory and practice. Interest develops in part from the underlying assumptions of recent theoretical perspectives that focus on opportunity structures for crime. Building upon these theoretical innovations a number of studies beginning in the late 1980s show that crime is concentrated in specific places in urban areas. This has led many scholars to argue that crime places would be a more effective focus of crime prevention activities than people involved in crime. Previous studies have shown that crime is concentrated at such micro places, but they have not examined critically whether our understanding of crime across place would have been seriously altered if we had used larger geographic units of analysis to characterize changes in crime rates over time. Our study uses trajectory analysis and GIS to examine this question. Our geographic analysis reveals a tendency for members of the same trajectory to be clustered. However, tremendous block by block variation in temporal patterns of juvenile crime is also exposed. These findings show that much would have been lost if we would have aggregated up from the street block and examined only units such as census block groups. We think these data suggest that much of the action of crime at place occurs at very micro units of geography such as street blocks, and that researchers should begin with micro units of analysis before moving to larger aggregates such as census block groups.

Criminogenic Facilities and Crime across Street Segments in Philadelphia: Uncovering Evidence about the Spatial Extent of Facility Influence

Objectives: Test whether the exposure of street segments to five different potentially criminogenic facilities is positively related to violent, property, or disorder crime counts controlling for sociodemographic context. The geographic extent of the relationship is also explored. Method: Facility exposure is operationalized as total inverse distance from each street segment in Philadelphia, PA, to surrounding facilities within three threshold distances of 400, 800, and 1,200 feet. All distances are measured using shortest path street distance. Census block group data representing ethnic heterogeneity, concentrated disadvantage, and stability are proportionally allocated to each street block. Negative binomial regression is used to model the relationships. Results: Exposure to bars and subway stations was positively associated with violent, property, and disorder crime at all distance thresholds from street segments. Schools were associated with disorder offenses at all distance thresholds. The effects of exposure to halfway houses and drug treatment centers varied by distance and by crime type. Conclusions: Facilities have a significant effect on crime at nearby places even controlling for sociodemographic variables. The geographic extent of a facility’s criminogenic influence varies by type of facility and type of crime. Future research should examine additional types of facilities and include information about place management.

'Situating' Simulation to Model Human Spatio-Temporal Interactions: An Example Using Crime Events

Many social phenomena have a spatio-temporal dimension and involve dynamic decisions made by individuals. In the past, researchers have often turned to geographic information systems (GIS) to model these interactions. Although GIS provide a powerful tool for examining the spatial aspects of these interactions, they are unable to model the dynamic, individual-level interactions across time and space. In an attempt to address these issues, some researchers have begun to use simulation models. But these models rely on artificial landscapes that do not take into account the environment in which humans move and interact. This research presents the methodology for ‘situating’ simulation through the use of a new modeling tool, Agent Analyst, which integrates agent-based modeling (ABM) and GIS. Three versions of a model of street robbery are presented to illustrate the importance of using ‘real’ data to inform agent activity spaces and movement. The successful implementation of this model demonstrates that: (1) agents can move along existing street networks; (2) land use patterns can be used to realistically distribute agent’s homes and activities across a city; and (3) the incidence and pattern of street robberies is significantly different when ‘real’ data are used.

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.

Aligning policing and public health promotion: insights from the world of foot patrol

Foot patrol work is rarely described in relation to public health, even though police routinely encounter health risk behaviors and environments. Through a qualitative study of foot patrol policing in violent ‘hotspots’ of Philadelphia, we explore some prospects and challenges associated with bridging security and public health considerations in law enforcement. Noting existing efforts to help advance police officer knowledge of, and attitudes toward health vulnerabilities, we incorporate perspectives from environmental criminology to help advance this bridging agenda. Extending the notion of capable guardianship to understand foot patrol work, we suggest that the way forward for theory, policy, and practice is not solely to rely on changing officer culture and behavior, but rather to advance a wider agenda for enhancing collective guardianship, and especially ‘place management’ for harm reduction in the city.

Exploring the relationship between foot and car patrol in violent crime areas

Purpose – The purpose of this paper is to describe how the Philadelphia Police Department instituted a large‐scale randomized controlled trial of foot patrol as a policing strategy and experienced 23 percent fewer violent crimes during the treatment period. The authors examine whether activities patrol officers were conducting might have produced the crime reduction. The activities of foot and car patrol officers research takes a closer look at what types are examined separately and differences between car patrol activities pre‐intervention and during the intervention are explored. Activities of foot versus car patrol officers during the study period are compared across treatment and control areas.Design/methodology/approach – Official data on police officer activity are used to compare activities conducted by foot patrol officers with those by car patrol officers in 60 treatment (foot beat) and 60 control areas consisting of violent crime hot spots. Activities of car patrol officers are described pre‐int...

The Variable Impacts of Public Housing Community Proximity on Nearby Street Robberies

Objectives: Use crime pattern theory to investigate the proximity effects of public housing communities on robbery crime while taking into account the presence of nearby nonresidential facilities. Method: The study uses data describing 41 Philadelphia public housing communities and their surrounds. Surrounds are defined using two increments of street block-sized buffers. Multilevel models (buffer areas nested around public housing communities) allowing the proximity effect to vary across communities and predicting its shape with public housing level predictors are estimated. Results: The multilevel models show that the shape of proximity effects varies across public housing communities and depends on community size, even after factoring in presence of nonresidential facilities. Spatially, multiple public housing communities close to one another have more intense robbery patterns. Conclusions: Labeling all public housing communities as equally criminogenic robbery exporters is unwarranted. In fact, some communities have lower robbery counts than the areas surrounding them. Consequently, effectively addressing robbery in and around public housing communities will require careful consideration of where the problem is located. Locating public housing communities more than two blocks apart may reduce robbery.

Strengthening Theoretical Testing in Criminology Using Agent-based Modeling:

Objectives: The Journal of Research in Crime and Delinquency (JRCD) has published important contributions to both criminological theory and associated empirical tests. In this article, we consider some of the challenges associated with traditional approaches to social science research, and discuss a complementary approach that is gaining popularity—agent-based computational modeling—that may offer new opportunities to strengthen theories of crime and develop insights into phenomena of interest. Method: Two literature reviews are completed. The aim of the first is to identify those articles published in JRCD that have been the most influential and to classify the theoretical perspectives taken. The second is intended to identify those studies that have used an agent-based model (ABM) to examine criminological theories and to identify which theories have been explored. Results: Ecological theories of crime pattern formation have received the most attention from researchers using ABMs, but many other criminological theories are amenable to testing using such methods. Conclusion: Traditional methods of theory development and testing suffer from a number of potential issues that a more systematic use of ABMs—not without its own issues—may help to overcome. ABMs should become another method in the criminologists toolbox to aid theory testing and falsification.

Informal Social Control and Crime Events

Informal social control at micro-level places such as addresses, collections of addresses, and streetblocks is a critical factor in understanding crime patterns. Historically, informal social control has been associated with community-level theories such as social disorganization, systemic theory, and collective efficacy. This article reviews several important streams of literature that address the role of informal social control in controlling crime at micro-level places. It begins with opportunity theories such as rational choice, routine activity, and crime pattern theories, which mention informal social control as playing a role in crime control. More detailed treatment of the role of informal social control is offered by theoretical work addressing “eyes on the street” and human territorial functioning. Together, these various theoretical perspectives provide the basis for the specification of mechanisms that reflect how informal social control can prevent crime events. The article explains each theory, discusses the spatial scale at which the dynamics operate, highlights gaps in the current body of knowledge, and proposes a two-pronged research path forward.