We combine growth theory with US Census data on individual schooling and wages to estimate the aggregate return to human capital and human capital externalities in cities. Our estimates imply that a one-year increase in average schooling in cities increases their aggregate labor productivity by...

I formulate and estimate a model of externalities within countries and technological interdependence across countries. I find that external returns to scale to physical capital within countries are 8 percent; that a 10 percent increase of total factor productivity of a country's neighbors raises...

Payoff heterogeneity weakens positive feedback in binary choice models in two ways. First, heterogeneity drives individuals to corners where they are unaffected by strategic complementarities. Second, aggregate behaviour is smoother than individual behaviour when individuals are heterogeneous....

We estimate the effect of international trade on average labor productivity at the country level. Our empirical approach relies on summary measures of trade that, we argue, are preferable on both theoretical and empirical grounds to the one conventionally used. In contrast to the marginally...

To learn more about the effect of economic conditions on civil war, we examine whether Sub-Saharan civil wars are more likely to start following downturns in the international price of countries’ main export commodities. The data show a robust effect of commodity price downturns on the...

The Industrial Revolution was characterized by technological progress and an increasing capital intensity. Why did real wages stagnate or fall in the beginning? I answer this question by modeling the Industrial Revolution as the introduction of a relatively more capital intensive production...

Returns to scale to capital and the strength of capital externalities play a key role for the empirical predictions and policy implications of different growth theories. We show that both can be identified with individual wage data and implement our approach at the city-level using US Census...

We estimate the aggregate long-run elasticity of substitution between more and less educated workers (the slope of the demand curve for more relative to less educated workers) at the US state level. Our data come from the (five)1950-1990 decennial censuses. Our empirical approach allows for...

Individual-specific uncertainty may increase the chances of reform being enacted and sustained. Reform may be more likely to be enacted because a majority of agents might end up losing little from reform and a minority gaining a lot. Under certainty, reform would therefore be rejected, but it...