Essays on health and human development

This dissertation consists of two chapters. The first chapter is concerned with the analysis of mechanisms behind the treatment effects of the Perry preschool program. The Perry Preschool program was a randomized social experiment with long run followup that supplemented the early environments of disadvantaged African American children. The Perry program has been shown to boost adult outcomes for both girls and boys, and thus evidence from the program is widely used in support of claims of the effectiveness of early childhood intervention programs. The program has a rate of return above the historical return to equity, although it had little lasting impact on the IQs of its participants. Using newly discovered data on the noncognitive skills collected a few years after the program finished, we find that experimentally induced changes in noncognitive skills explain a sizable portion of later-life treatment effects for adult outcomes, particularly crime outcomes. This paper contributes to an emerging literature on the importance of noncognitive skills in explaining a variety of social outcomes.;The second chapter investigates whether post-high school educational investments and childhood noncognitive traits causally affect longevity. The answer to this question is unclear in the literature, largely because not enough is known about possible confounding factors and because it is hard to find instrumental variables for post-compulsory education. I examine whether there are confounding factors among early cognitive and noncognitive traits that causally affect both education and longevity, inducing spurious correlation between them. I represent childhood noncognitive traits by three personality traits widely recognized in personality psychology Conscientiousness, Openness, and Extraversion-and find that only childhood Conscientiousness has strong effects on both education and longevity. I estimate a model which uses Conscientiousness and education as arguments of a production function for longevity. The model accounts for the endogeneity of education, measurement error in the proxies for Conscientiousness, age-dependence in the effect of education on longevity, and the interaction between education and Conscientiousness in producing longevity. Identification of causal effects is based on conditional independence assumption, which is motivated by richness of the data. I estimate the model using the 1922--1991 Terman life cycle data of children with high ability, a prospective study with unique life cycle information including detailed background characteristics, early health measures, personality ratings, IQ, and mortality observations. My results show that Conscientiousness and education both causally increase longevity for males. However, the effect of Conscientiousness on longevity is only strong at low levels of education, and the effect of education on longevity is especially strong at low levels of Conscientiousness. In addition, I show that a failure to account for Conscientiousness leads to a generally upward bias in the estimate of the effect of education on longevity. The bias from omitting Conscientiousness is comparable to the bias from omitting all other control variables in my model. For females, the effects of education and Conscientiousness are generally not precisely determined.