Implementing the First RCT with the Police in Chile: What Worked, What Didn’t and What’s Next

• In Event: Advances in Experimental Methods Panel 1 : Experimental Frontiers in Policing and Threat Assessment

Abstract

This presentation examines the first randomised controlled trial (RCT) with the police in Chile, conducted in partnership with Carabineros de Chile. The study tested a foot patrol strategy in "priority areas"—street segments identified as both crime and harm hotspots.
Of the 159 priority areas identified, 49 were randomly assigned to receive patrols, while the remaining 110 served as controls. Officers were instructed to patrol the experimental areas 3–4 times daily for at least 15 minutes per visit, while control areas remained unknown to the police, maintaining the integrity of the randomisation process.
A T-Test analysis revealed a statistically significant reduction in total crime within the experimental areas (p < 0.05, Cohen’s D = 0.49). However, the reduction in crime harm was not statistically significant. The study’s monitoring process exposed major compliance challenges: patrols visited experimental areas far less than intended, averaging just one visit per day over the three-month intervention period. Additionally, the short duration of the study may have limited the intervention's overall impact.
This presentation will explore how police compliance and the timeframe of the intervention shaped the results, highlighting key obstacles in implementing experimental policing strategies in Latin America. It will conclude with practical recommendations for improving adherence in future trials, offering insights into the challenges and opportunities of evidence-based policing in the region.

Author

• Cristóbal Weinborn, Pontificia Universidad Católica de Chile