The Impact of the First Professional Police Forces on Crime
研究1829年伦敦大都会警察（全球首个职业警察部队）成立对犯罪的影响，发现暴力犯罪显著减少，但财产犯罪未见下降。
Abstract This paper evaluates the effect on crime of creating a fundamental modern-day institution: centralized professional police forces tasked with preventing crime. We study the 1829 formation of the London Metropolitan Police—the first professional force worldwide. Using newly digitized and geocoded crime and police data together with difference-in-differences and pre–post designs, we find evidence of a significant reduction in violent crimes (despite the possibility of offsetting increases in clearance and reporting rates). In contrast, a reduction in property crime is not visible.