Indirect Effects of a Policy Altering Criminal Behavior: Evidence from the Italian Prison Experiment
利用2006年意大利监狱赦免政策，研究发现前囚犯同伴的剩余刑期增加对其累犯率的降低效果至少与自身刑期增加的效果相当，并估算出犯罪的社会乘数为2。
We exploit the 2006 Italian prison pardon to evaluate peer effects in criminal behavior. The pardon randomly commutes actual sentences to expected sentences for 40 percent of the Italian prison population. Using prison and geographical origin to construct reference groups for former inmates, we find large indirect effects of this policy. In particular, we find that the reduction in the individuals' recidivism due to an increase in their peers' residual sentence is at least as large as their response to an increase in their own residual sentence. From this result we estimate a social multiplier in crime of two.