The Deterrent Effects of Prison: Evidence from a Natural Experiment
利用意大利2006年集体赦免法案作为自然实验，分析服刑时间减少对再犯率的影响，发现预期刑期增加1个月使再犯概率降低0.16个百分点。
The Collective Clemency Bill passed by the Italian Parliament in July 2006 represents a natural experiment to analyze the behavioral response of individuals to an exogenous manipulation of prison sentences. On the basis of a unique data set on the postrelease behavior of former inmates, we find that 1 month less time served in prison commuted into 1 month more in expected sentence for future crimes reduces the probability of recidivism by 0.16 percentage points. From this result we estimate an elasticity of average recidivism with respect to the expected punishment equal to −0.74 for a 7-month period.