How Much Can We Generalize From Impact Evaluations?
利用影响评估结果的新数据集，发现效应大小存在大量异质性，且与实施机构类型等研究特征系统相关，考虑这些特征可显著降低异质性。
Abstract Impact evaluations can help to inform policy decisions, but they are rooted in particular contexts and to what extent they generalize is an open question. I exploit a new data set of impact evaluation results and find a large amount of effect heterogeneity. Effect sizes vary systematically with study characteristics, with government-implemented programs having smaller effect sizes than academic or non-governmental organization-implemented programs, even controlling for sample size. I show that treatment effect heterogeneity can be appreciably reduced by taking study characteristics into account.