Using the NLSY data set, this paper formulates and then empirically estimates the production processes for social, motivational and cognitive skills during early childhood development and the long-term effects of these skills on learning and life-time earnings of an individual. Using these...

I show that in a conventional Ramsey model, between one-fourth and one-half of the global income distribution can be explained by a single factor: The effect of large, persistent differences in national average IQ on the private marginal product of labor. Thus, differences in national average IQ...

Human capital plays an important role in the theory of economic growth, but it has been difficult to measure this abstract concept. We survey the psychological literature on cross-cultural IQ tests, and conclude that modern intelligence tests are well-suited for measuring an important form of a...

Two alternative models of parental investments in children's human capital are considered and tested empirically using the Indonesian Family Life Survey (IFLS). The pure loan model and the reciprocity with two-sided altruism model yield different predictions about the effect of children's...

I show that in a conventional Ramsey model, between one-fourth and one- half of income differences across countries can be explained by a single factor: The steady-state effect of large, persistent differences in national average IQ on worker productivity. These differences in cognitive...