This study examined street robbery patterns in Philadelphia, Pennsylvania, from the years 2009 to 2011 to determine whether the effects of potentially criminogenic places are different across different periods of the day. Census block (N = 13,164) street robbery counts across four periods (6:45 a.m. to 9:59 a.m., 10:00 a.m. to 4:29 p.m., 4:30 p.m. to 9:14 p.m., and 9:15 p.m. to 6:44 a.m.) were modeled with 12 different potentially criminogenic places, 3 measures of illicit markets, 4 compositional control variables, and spatially lagged versions of the 12 potentially criminogenic places and population using simultaneously estimated negative binomial regression models. Differences in the magnitudes of the parameter estimates across the time periods were assessed with Wald tests. Overall, the patterns across the four models were mostly consistent with the effects hypothesized based on the study's crime pattern theory and time-geography theoretical frame; yet differences in the magnitudes of the coefficients were less pronounced than hypothesized. Overall, the results provide moderate support for the crime pattern theory and time-geography explanation of spatial-temporal robbery patterns; however, numerous points are raised for future crime and place research.An axiom of the crime and place literature is that certain types of places are important predictors of the spatial distribution of crime (P. L. Brantingham and P. J. Brantingham, 1999; P. J. Brantingham and P. L. Brantingham, 1991;Wilcox and Eck, 2011) and even can be used to forecast crime events (Caplan, Kennedy, and Miller, 2010). The link among certain types of places and higher crime levels has been empirically demonstrated for many different types of places, such as high schools, bars and taverns, convenience stores, public transportation stations, check-cashing stores, liquor stores, parks, and public housing communities (

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.

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KEYWORDS: Philadelphia Foot Patrol Experiment, hot spots policing, initial deterrence decay, residual deterrence decay, inverse 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 * The authors would like to thank Police Commissioner Charles Ramsey, Chief Administrative Officer Nola Joyce, Deputy Commissioner Richard Ross, Deputy Commissioner Tommy Wright, and Deputy Commissioner Kevin Bethel for their support of this project and their ongoing interest in collaborative research. We also would like to thank the Philadelphia police officers and the district-level supervisors who were the subjects of the foot patrol experiment, and who provided us with the insights and context that helped inform this research. Furthermore,

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