For police, there are two key features of crime: people and places. The work of police has traditionally focused on people—predominately offenders. By 2000, the focus of police on people had increasingly given way to a focus on places—that is, the particular physical locations in which offenders act. The transition occurred because research demonstrated that crime does not occur randomly in space; instead, it is highly clustered in small geographic areas and this concentration tends to remain stable over time. Groundbreaking research by Larry Sherman and colleagues in the mid-1980s showed that a small fraction of addresses generated the majority of police workload in Minneapolis, Minnesota. Subsequent research reinforced this important finding: Crime is more predictable by location than by any other factor.

The predictability of ...