An impact evaluation study did not find a statistically significant decrease in crime at the hot spots that received isolated police and public service improvement actions. The intervention effect was greatest in segments that received both police and public services, resulting in a large and statistically significant 45.6% decrease in the number of reported crimes in those segments. In addition, the combined effect of the two interventions was greatest at the highest crime hot spots. The results further suggest that there may have been a displacement of crime to neighboring streets, with a small increase in each of the 77,000 streets within 250 meters of the treated hot spots [1].
Another impact evaluation study found that, contrary to consensus, intensified State presence does not generate a substantially large or statistically significant reduction in crime. There was evidence of modest direct effects, but with displacement of crime to nearby areas, especially property crime. The study’s confidence intervals suggest that total crime reductions by more than 2% can be ruled out for the two interventions [2].
Although the possibility that all crime has moved to other streets cannot be ruled out, there are indications that the total number of violent crimes, especially homicides and rapes, fell by 8%. Victimization surveys also showed that there was an increase in the perception of safety in the segments that received the two actions simultaneously [1] [2].