Philadelphia Hot Spots Policing

Summary

Rather than spreading patrol thinly across precincts, hot spots policing concentrates resources at the tiny fraction of locations responsible for the majority of crime. Sherman and Weisburd's Philadelphia experiment—later extended by Ratcliffe and colleagues—found that concentrating patrol at high-crime micro-locations reduced crime significantly and, critically, did not push crime into adjacent streets. In fact, crime fell in nearby areas too (diffusion of benefits). The study is the foundation of evidence-based policing and one of the most replicated criminology experiments.

Research question

"Does concentrating police patrol at high-crime 'hot spots' (micro-locations) reduce crime, and does crime displace to adjacent areas?"

Methodology

Result

Positive

−15% crime incidents at treated hot spots; no evidence of displacement to adjacent areas; 'diffusion of benefits' observed (crime fell in areas immediately adjacent to treated spots)

Evidence strength

Strong

Randomized trial, replicated across multiple sites or studies.

Replication status

Replicated