Micro Places – Blattman et al. (2017)

Study Reference:

Blattman, C., Green, D., Ortega, D., & Tobón, S. (2017). Place-based interventions at scale: The direct and spillover effects of policing and city services on crime (No. w23941). National Bureau of Economic Research.

Location in the Matrix; Methodological Rigor; Outcome:

Micro places; Focused; Proactive; Very rigorous; Mixed findings

What police practice or strategy was examined?

This study examines the deterrent effects and potential displacement of two interventions: intensive policing and municipal services at crime hot spots in Bogotá, Colombia. Intensive policing involved officers increasing the amount of patrol visibility in hot spots (6 visits per day for roughly 15 minutes each), by conducting everyday law enforcement activities (e.g., criminal record checks, stop & frisks, community visits). Municipal services approaches involved street segments being evaluated for physical disorder by the city’s municipal contractors as directed by the Mayor and receiving municipal maintenance services, including streetlight repair and garbage collection. The intervention lasted for 8 months.

How was the intervention evaluated?

1,919 high-crime street segments were identified and randomly assigned to receive intensive patrol, municipal services, both, or neither. To measure any potential spillover effects from the treatment areas, the researchers identified control hot spots according to their spatial relationship to the nearest treatment hot spots and divided them into categories: 0-250 meters (m) from a treatment site, 250-500m, and >500m. The intervention was evaluated using data on reported crimes, a survey of 24,000 Bogotá citizens living on the 1,919 experimental segments as well as residents on 480 segments outside the experimental sample, and GPS data on officer location. Self-reported crimes, perceptions of security, and attitudes towards the police and the local government were measured in the survey.

What were the key findings?

The 75 segments that received both interventions experienced a 45.6% statistically significant decrease in reported crimes. However, there was no evidence that either intervention reduced crime. Meanwhile, the spillover analysis provided evidence that the intensive patrol treatment displaced crime. Any crime deterred was more than made up for by a rise in crime on control streets within 250m. This displacement mainly occurred in the form of property crime. Overall, the intervention did not reduce crime at the city level. Perceived risk of crime decreased significantly only in the segments that received both interventions. However, for hot spots receiving only one type of intervention, this did not significantly impact the perceived risk of crime (although the direction of the effect is consistent with increased perceived safety).

What were the implications for law enforcement?

The authors suggest that while implementing both intense policing and increased municipal services may reduce crime in hot spots and increase perceptions of safety, practitioners should evaluate each intervention’s effectiveness not only in targeted places, but also in the surrounding areas. Because certain crimes may be displaced, particularly due to increased policing levels at the hot spots, the authors note that it is important to consider the effects of the intervention beyond the targeted locations.

Where can I find more information about this intervention, similar types of intervention, or related studies?