  Hot-spot-based policing programs aim to deter crime through increased
proactive patrols at high-crime locations. While most hot spot programs target
easily identified chronic hot spots, we introduce models for predicting
temporary hot spots to address effectiveness and equity objectives for crime
prevention, and present findings from a crossover experiment evaluating
application of hot spot predictions to prevent serious violent crime in
Pittsburgh, PA. Over a 12-month experimental period, the Pittsburgh Bureau of
Police assigned uniformed patrol officers to weekly predicted chronic and
temporary hot spots of serious violent crimes comprising 0.5 percent of the
city's area. We find statistically and practically significant reductions in
serious violent crime counts within treatment hot spots as compared to control
hot spots, with an overall reduction of 25.3 percent in the FBI-classified Part
1 Violent (P1V) crimes of homicide, rape, robbery, and aggravated assault, and
a 39.7 percent reduction of African-American and other non-white victims of P1V
crimes. We find that temporary hot spots increase spatial dispersion of patrols
and have a greater percentage reduction in P1V crimes than chronic hot spots
but fewer total number of crimes prevented. Only foot patrols, not car patrols,
had statistically significant crime reductions in hot spots. We find no
evidence of crime displacement; instead, we find weakly statistically
significant spillover of crime prevention benefits to adjacent areas. In
addition, we find no evidence that the community-oriented hot spot patrols
produced over-policing arrests of minority or other populations.
