How Small are Crime “Hot Spots”?

Authors: Cory Schnell, Rutgers University, Anthony Braga, Northeastern University, and Eric Piza, John Jay College of Criminal Justice, City University of New York

Goal of the Study: This study attempts to analyze the spatial variability of violent crime in the city of Chicago at three different levels/units of analysis. In turn, this will provide quantitative, spatiotemporal researchers with guidance in explaining the spatial variability of crime.

Background Information: The spatial analysis of crime at the microgeographic unit has seen a resurgence in the field of criminology since David Weisburd (2015) published his Law of Crime Concentration during his Sutherland Address in 2014. In doing so, he sent the field of criminology down a path focusing on studying crime via hot spots analysis and at smaller units of analysis. In the past, we (as criminologists) were studying crime at the individual-level and at the city-level. In turn, Schnell and colleagues (2017) analyzed violent crime in the city of Chicago at three different levels (Community Areas, Neighborhood Clusters, and Street Segments) in an attempt to justify the use of smaller units of analysis in criminology.

Research Methodology: Violent crime reported to the police between 2001 and 2014 were analyzed. In total, 359,786 crimes were geocoded to 41,926 street segments within 342 neighborhood clusters which fell inside 76 community area within the city of Chicago.

Results: Findings indicated that the analysis of violent crime at the level of street segments explained between 56 and 65 percent of the variation in violent crime rates across the city of Chicago. This range of variance explained exceeded the two larger geographic analyses (neighborhood clusters and community areas). In sum, Schnell and colleagues (2017) supported Weisburd’s (2015) Law of Crime Concentration.

“What does it mean?”: These findings mean two different things: First, violent crime is concentrated to a small percentage of locations within a city. This means that there are a few locations that deal with a high percentage of crimes. This is what scholars refer to as “Hot Spots”, specific locations that deal with high percentages of criminal activity. Second, these findings show that these “Hot Spots” can be identified at a very specific level, going as far as identifying the street segment that these high levels of crime occur at. A street segment can be thought of as a road between two intersections.

Link to article: https://academicworks.cuny.edu/jj_pubs/178/

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