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Intergenerational and Intragenerational Externalities of the Perry Preschool Project

This paper examines the impact of the iconic Perry Preschool Project on the children and siblings of the original participants. The children of treated participants have fewer school suspensions, higher levels of education and employment, and lower levels of participation in crime, compared with the children of untreated participants. Impacts are especially pronounced for the children of male participants. These treatment effects are associated with improved childhood home environments. The intergenerational effects arise despite the fact that families of treated subjects live in similar or worse neighborhoods than the control families. We also find substantial positive effects of the Perry program on the siblings of participants who did not directly participate in the program, especially for male siblings.

The Perry Preschoolers at Late Midlife: A Study in Design-Specific Inference

This paper presents the first analysis of the life course outcomes through late midlife (around age 55) for the participants of the iconic Perry Preschool Project, an experimental high-quality preschool program for disadvantaged African-American children in the 1960s. We discuss the design of the experiment, compromises in and adjustments to the randomization protocol, and the extent of knowledge about departures from the initial random assignment. We account for these factors in developing conservative small-sample hypothesis tests that use approximate worst-case (least favor-able) randomization null distributions. We examine how our new methods compare with standard inferential methods, which ignore essential features of the experimental setup. Widely used procedures produce misleading inferences about treatment effects. Our design-specific inferential approach can be applied to analyze a variety of compromised social and economic experiments, including those using re-randomization designs. Despite the conservative nature of our statistical tests, we find long-term treatment effects on crime, employment, health, cognitive and non-cognitive skills, and other outcomes of the Perry participants. Treatment effects are especially strong for males. Improvements in childhood home environments and parental attachment appear to be an important source of the long-term benefits of the program.