We argue that the key impediment to accurate measurement of the effect of police on crime is not necessarily … simultaneity bias, but bias due to mismeasurement of police. Using a new panel data set on crime in medium to large U.S. cities … crime more so than property crime …

between the racial composition of a city's police force and the racial patterns of arrests and crime. Increases in the number … police officers has a less clear-cut impact on crime rates. It appears that own-race policing may be more effective in … reducing property crime, but no systematic differences are observed for violent crime. These results are consistent either with …

Previous empirical studies have typically uncovered little evidence that police reduce crime. One problem with those … studies is a failure to adequately deal with the simultaneity between police and crime: while police may or may not reduce … crime, there is little doubt that expenditures on police forces are an increasing function of the crime rate. In this study …