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 capital (which determines life span). We find that cross-country differences in productivity and taxes go a long way toward explaining the observed differences in fertility and mortality.

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 this to be incorrect. Once the appropriate driving forces are taken into account, the neoclassical model can account for 'slow' adoption. We illustrate this by developing an industry model to study the equilibrium rate of diffusion of tractors in the U.S. between

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, consequently, estimates of Mincerian rates of return across countries. We find that effective human capital per worker varies substantially across countries. Cross-country differences in Total Factor Productivity (TFP) are significantly smaller than found in previous studies. Our model implies that output per worker is highly responsive to changes in TFP and demographic variables.

In this paper, we build on the recent literature on coordination problems to construct a model in which there is potential for low-output equilibrium. We show that the conditions that guarantee interior Walrasian equilibria in conjunction with a continuity restriction on strategies rule out equilibria with extremely low levels of activity (zero activity), which is a distinguishing feature of many existing models. We study the case of separability and show that there is no rationing and, hence, no equilibrium unemployment. In addition, in a numerical example, we find that there is a unique symmetric equilibrium.

The authors study the problem of optimal taxation in three infinite-horizon, representative-agent endogenous growth models. The first model is a convex model in which physical and human capital are perfectly symmetric. The authors' second model incorporates elastic labor supply through a Lucas-style technology. Analysis of these two models points out the danger of assuming that government expenditures are exogenous. In their third model, the authors include government expenditures as a productive input in capital formation, showing that the limiting tax rate on capital is no longer zero. In numerical simulations, they find similar effects on growth and welfare in all three models.

We study the problem of optimal taxation in three infinite-horizon, representative-agent endogenous growth models. The first model is a convex model in which physical and human capital are perfectly symmetric. Our second model incorporates elastic labor supply through a Lucas-style technology. Analysis of these two models points out the danger of assuming that government expenditures are exogenous. In our third model, we include government expenditures as a productive input in capital formation, showing that the limiting tax rate on capital is no longer zero. In numerical simulations, we find similar effects on growth and welfare in all three models.