Police numbers up, crime rates down. The effect of police on crime in the Netherlands, 1996-2003

We present evidence on the effect of greater numbers of police personnel on crime and nuisance reduction in the Netherlands. We use a multiple time series design with police regions as the unit of analysis, covering the period 1996-2003. During this period, police resources increased substantially. The growth in additional resources differed greatly between regions, allowing us to use this policy intervention to identify the effect of police on crime and nuisance. We control for regional economic, social and demographic factors and for national trends that might obscure the effect of police on crime. We find significantly negative effects of higher police levels on property crime, violent crime and nuisance. Our estimates suggest that a substantial proportion of the decline in crime and nuisance during the period 1996-2003 is attributable to the increase in police personnel.