Hot Spots Interventions at Scale: the Direct and Spillover Effects of Policing and City Services on Crime

88 Pages Posted: 12 Oct 2017 Last revised: 1 May 2018

Christopher Blattman

University of Chicago, Harris School of Public Policy; National Bureau of Economic Research (NBER)

Donald P. Green

Columbia University

Daniel Ortega

CAF Development Bank of Latin America

Santiago Tobon

University of Chicago; Universidad de los Andes, Colombia - Department of Economics; Innovations for Poverty Action

Multiple version iconThere are 2 versions of this paper

Date Written: April 17, 2017

Abstract

To reduce crime, cities focus state resources in high-crime “hot spot” streets. A U.S. literature argues that this approach, especially policing, has large direct effects and beneficial spillovers - a finding consistent with criminal rents being concentrated in a very small number of streets. We need large samples, however, to accurately assess local spillovers. An experiment in Bogotá, Colombia is an order of magnitude larger than previous opportunities to evaluate such policies. The city identified 1,919 hot spots and randomly assigned them to either 8 months of doubled policing, greater municipal services (cleanup and lighting), both interventions, or neither. At this scale, however, spillovers in dense networks can introduce bias and complicate variance estimation through “fuzzy clustering”. We show valid hypothesis testing requires randomization inference. We find that intensive policing or municipal services alone had small direct effects on security in hot spots, but together both interventions reduced crime substantially. Nonetheless, the evidence points to both interventions displacing crime to neighboring streets. On average, aggregate crime appears to have increased in Bogotá, and we can rule out decreases in aggregate crime of more than 1-2%. These results are consistent with a situation where illegal opportunities are not highly concentrated in a city, a large proportion of crime (especially property crime) has a sustained motive, and criminals shift activities to places where they have lower risks of detection.

Keywords: Crime, Violence, Police, Public Services, State Building, Spillovers, Field Experiment

JEL Classification: K42, O17, E26, J48, C93

Suggested Citation

Blattman, Christopher and Green, Donald P. and Ortega, Daniel and Tobon, Santiago, Hot Spots Interventions at Scale: the Direct and Spillover Effects of Policing and City Services on Crime (April 17, 2017). Available at SSRN: https://ssrn.com/abstract=3050823 or http://dx.doi.org/10.2139/ssrn.3050823

Christopher Blattman (Contact Author)

University of Chicago, Harris School of Public Policy ( email )

1101 East 58th Street
Chicago, IL 60637
United States

National Bureau of Economic Research (NBER) ( email )

1050 Massachusetts Avenue
Cambridge, MA 02138
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Donald P. Green

Columbia University ( email )

7th Floor, International Affairs Bldg.
420 W. 118th Street
New York, NY 10027
United States

Daniel Ortega

CAF Development Bank of Latin America ( email )

Ave. Luis Roche
P.O. Box Carmelitas 5086 Torre CAF, Altamira
Caracas
United States

Santiago Tobon

University of Chicago ( email )

1155 East 60th Street
Chicago, IL 60637
United States

Universidad de los Andes, Colombia - Department of Economics ( email )

Carrera 1a No. 18A-10
Santafe de Bogota, AA4976
Colombia

Innovations for Poverty Action ( email )

1731 Connecticut Ave, 4th floor
New Haven, CT 20009
United States

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