Empirical evidence suggests that there is a long lag between the time a new technology is introduced and the time at which it is widely adopted. The conventional wisdom is that these observations are inconsistent with the predictions of the frictionless neoclassical model. In this paper we show...

Many new technologies display long adoption lags, and this is often interpreted as evidence of frictions inconsistent with the standard neoclassical model. We study the diffusion of the tractor in American agriculture between 1910 and 1960-a well-known case of slow diffusion-and show that the...

We reevaluate the role of human capital in determining the wealth of nations. We use standard human capital theory to estimate stocks of human capital and allow the quality of human capital to vary across countries. Our model can explain differences in schooling and earnings profiles and...

Why do fertility rates vary so much across countries? Why are European fertility rates so much lower than American fertility rates? To answer these questions we extend the Barro-Becker framework to incorporate the decision to accumulate human capital (which determines earnings) and health...

Our aim in this paper is to exposit a convex model of equilibrium growth. The model is strictly in the Solow tradition. The model has two features which distinguish it from most other work on the subject. These are, first, that the model is convex on the technological side and, eecond, that...