Uncovering Gender Differences in the Effects of Early Intervention: A Reevaluation of the Abecedarian, Perry Preschool, and Early Training Projects

The view that the returns to public educational investments are highest for early childhood interventions stems primarily from several influential randomized trials - Abecedarian, Perry, and the Early Training Project - that point to super-normal returns to preschool interventions. This paper presents a de novo analysis of these experiments, focusing on core issues that have received little attention in previous analyses: treatment effect heterogeneity, over-rejection of the null hypothesis due to multiple inference, and robustness of the findings to attrition and deviations from the experimental protocol. The primary finding of this reanalysis is that girls garnered substantial short- and long-term benefits from the interventions, particularly in the domain of total years of education. However, there were no significant long-term benefits for boys. These conclusions change little when allowance is made for attrition and possible violations of random assignment.