Giovanni Mastrobuoni (Collegio Carlo Alberto)

"Police Patrols and Crime"

13 November 2017, 12:45 pm


An influential literature has used the aftermath of terrorist attacks to estimatelarge effects of police street deployment on crime. However, the elasticities obtainedin these settings may not easily extrapolate to more standard circumstances. Thispaper exploits a natural experiment that aimed to increase police presence in morethan 6,000 well-defined areas, by economically-realistic amounts and under relativelynormal circumstances. Using data transmitted by GPS devices worn by police offi-cers, we first document exogenous and discontinuous changes in patrolling intensity.We then find that the relation between crime and police patrolling is not statisticallydifferent from zero, and that the standard errors are small enough to reject relativelysmall elasticities. We discuss and empirically evaluate explanations for the apparentlack of deterrence.