Inference for estimates of treatment effects with clustered data requires great care when treatment is assigned at the group level. This is true for both pure treatment models and difference-in-differences regressions. Even when the number of clusters is quite large, cluster-robust standard...

Researchers are often interested in estimating the causal effect of some "treatment" on individual criminality. For example, two recent prominent papers in Criminology have attempted to estimate the respective direct effects of marriage and gang participation on individual criminal activity. One...