there is limited overlap in the covariate distributions between the treatment groups. But such limited overlap can also have … by the number of observations in the areas of limited overlap. At least some of these "local sample sizes" are often very …

generalizability of field experiments: the internal and external overlap and unconfoundedness conditions. We experimentally varied the … degree of overlap in disjoint sub-samples from a recruitment experiment with more than 3,000 public schools, mimicking small … improved overlap by balancing covariate dependencies and variances instead of focusing on individual mean values. We assess the …