Improving Security through Concentrated Policing in Bogotá, Colombia
Summary of the Randomized Evaluation
Country
Colombia (Bogotá)Researchers
Chris Blattman, Donald Green, Daniel Mejia, Daniel Ortega, Santiago TobónMethods
Researchers conducted a randomized controlled trial (RCT) to evaluate the impact of concentrated policing and municipal clean-ups on crime reduction and displacement in Bogotá, Colombia. The study targeted 1,919 high-crime street segments, randomly assigning them to one of four groups: concentrated policing, municipal clean-ups, both interventions, or a control group with no special interventions.
Context:
Crime in Bogotá is spatially concentrated, with a small percentage of street segments accounting for a significant portion of homicides and other crimes. The intervention aimed to address these high-crime areas through increased police presence and municipal maintenance, such as street light repairs, graffiti removal, and garbage collection. The study also aimed to measure potential crime displacement to neighbouring areas.
Intervention Details
- Hot Spots Policing: Increased police patrols from 90 to almost 180 minutes per day on targeted streets. Patrol schedules varied, focusing on high-risk times and locations.
- Municipal Clean-Ups: The Mayor’s office directed maintenance teams to diagnose and address issues on targeted streets, including repairs and cleaning.
- Combined Intervention: Both increased police patrols and municipal maintenance were implemented together on selected streets.
- Comparison Group: No special interventions were conducted.
Data was collected through surveys of residents' perceived incidence of crime, self-reported victimization, and police reports. The study also evaluated spillover effects on streets within 250- and 500-meter radii of targeted hot spots.
Results
- Combined Interventions: When both increased policing and municipal clean-ups were implemented together, there was a significant decrease in reported crimes on targeted streets, with a reduction of about 57% in reported crimes. However, this estimate is based on a small sample and should be interpreted cautiously.
- Individual Interventions: Neither concentrated policing nor municipal clean-ups alone led to significant decreases in crime on targeted streets.
- Crime Displacement: Most crime, particularly property crime, appeared to be displaced to nearby streets. The overall impact on city-wide crime levels was minimal, with only a slight indication of a decrease in violent crimes such as homicides and rapes.
- Property vs. Violent Crime: The displacement effect was primarily driven by economically motivated property crimes. There is suggestive evidence that violent crimes decreased overall, but these results are ambiguous and require further research.
Policy Lessons
The findings suggest that while concentrated policing and municipal clean-ups can reduce crime in targeted areas, the interventions may also displace crime to adjacent streets. This highlights the importance of considering spillover effects in crime reduction strategies. Further research, particularly large-scale randomized evaluations across multiple cities, is needed to better understand the city-wide impacts of place-based tactics and to develop more effective crime reduction policies.
The study contributes new evidence to the ongoing debate about the efficacy of hot spot policing and municipal maintenance, particularly in the context of Latin American cities.
