The Short- and Long-Run Effects of Private Law Enforcement: Evidence from University Police
研究美国一所大学私人警察力量扩张对城市犯罪的影响，发现短期内无变化，但长期显著降低暴力犯罪，表明私人执法效果存在延迟。
Over a million people in the United States are employed in private security and law enforcement, yet very little is known about the effects of private police on crime. The current study examines the relationship between a privately funded university police force and crime in a large US city. Following an expansion of the jurisdictional boundary of the private police force, we see no short-term change in crime. However, using a geographic regression discontinuity approach, we find large impacts of private police on public safety, with violent crime in particular decreasing. These contradictory results appear to be a consequence of a delayed effect of private police on crime.