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Empirical studies in the economics of education, the measurement of skill gaps, the impacts of interventions on skill formation, and the value-added literature rely on psychometrically validated test scores. Test scores are taken as measures of an invariant scale of human capital compared over time and people. We examine if conventional skill measures are comparable on mastery of specific task knowledge. An unusually rich dataset from an early childhood intervention is used to test the assumption of scale invariance. We reject the scale invariance hypothesis for multiple skills and cast doubt on the uncritical use of test scores in research. [Additional support for this report was provided by the Institute for New Economic Thinking.]

We develop and estimate a life-cycle model in a rational addiction framework where youth choose to smoke, attend school, work part-time, and consume while facing borrowing constraints. The model features multiple channels for studying the reciprocal causal effects of addiction and education. Variations in endowments and cigarette prices are sources of identification. We show that education causally reduces smoking. A counterfactual experiment finds that in absence of cigarettes, college attendance rises by three percentage points in the population. A practical alternative of 40% additional excise tax achieves similar results. Impacts vary substantially across persons of different cognitive and non-cognitive abilities.

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 favorable) 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. [This research was supported in part by the American Bar Foundation.]

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. [Additional support for this research was provided by the American Bar Foundation.]