This paper assesses the impact of pollution on worker productivity by relating exogenous daily variations in ozone with productivity of agricultural workers as recorded under piece rate contracts. We find robust evidence that ozone levels well below federal air quality standards have a...

Cross-country labor productivity differences are larger in agriculture than in non-agriculture. We propose a new explanation for these patterns in which the self-selection of heterogeneous workers determines sector productivity. We formalize our theory in a general-equilibrium Roy model in which...

We study the determinants of differences in farm-size across countries and their impact on agricultural and aggregate productivity using a quantitative sectoral model featuring a distribution of farms. Measured aggregate factors (capital, land, economy-wide productivity) account for ? of the...

New ideas, products, and practices take time to diffuse, a fact that is often attributed to some form of heterogeneity among potential adopters. This paper examines three broad classes of diffusion models -- contagion, social influence, and social learning -- and shows how to incorporate...

Geography and social links shape economic interactions. In industries, schools, and markets, the entire network determines outcomes. This paper analyzes a large class of games and obtains a striking result. Equilibria depend on a single network measure: the lowest eigenvalue. This paper is the...

A new data set facilitates study of learning spillovers in World War II shipbuilding. Our results contain two principal but contrasting themes. First, learning spillovers were a significant source of productivity growth, and may have contributed more than conventional learning effects. Second,...

Recent developments in computer networks have driven the cost of distributing information virtually to zero, creating extraordinary opportunities for sharing product evaluations. The authors present pricing and subsidy mechanisms that operate through a computerized market and induce the...

This paper investigates the role of social learning in the diffusion of a new agricultural technology in Ghana. We use unique data on farmers' communication patterns to define each individual's information neighborhood. Conditional on many potentially confounding variables, we find evidence that...

Agents face a coordination problem akin to the adoption of a network technology. A principal announces investment subsidies that, at minimal cost, attain a given likelihood of successful coordination. Optimal subsidies target agents who impose high externalities on others and on whom others...

This paper documents the pervasiveness of job polarization in 16 Western European countries over the period 1993-2010. It then develops and estimates a framework to explain job polarization using routine-biased technological change and offshoring. This model can explain much of both total job...