We develop a framework for studying trade in vertically and horizontally differentiated products. In our model, consumers with heterogeneous incomes and tastes purchase a homogeneous good as well as making a discrete choice of quality and variety of a differentiated product. The distribution of...

We develop a two-country model of endogenous innovation and imitation in order to study the interactions between these two processes. Firms in the North race to bring out the next generation of a set of technology-intensive products. Each product potentially can be improved a countably infinite...

We develop a model of repeated product improvements in a continuum of sectors. Each product follows a stochastic progression up a quality ladder. Progress is not uniform across sectors, so an equilibrium distribution of qualities evolves over time. But the rate of aggregate growth is constant....

This paper shows that in American states balanced budget rules are effective in enforcing fiscal discipline but they have no costs in terms of increased output variability. More specifically, we show that tighter fiscal rules are associated with larger average surplus and lower cyclical...

Forward-looking investments determine the resilience of firms' supply chains. Such investments confer externalities on other firms in the production network. We compare the equilibrium and optimal allocations in a general equilibrium model with an arbitrary number of vertical production tiers....

What is the optimal number of currencies in the world? Common currencies affect trading costs and, thereby, the amounts of trade, output, and consumption. From the perspective of monetary policy, the adoption of another country's currency trades off the benefits of commitment to price stability...

We investigate how the number and size of local political jurisdictions in an area is determined. Our model focuses on the tradeoff between the benefits of economies of scale and the costs of a heterogeneous population. We consider heterogeneity in income, race, ethnicity, and religion, and we...

This paper evaluates the effects of fiscal policy on investment using a panel of OECD countries. In particular, we investigate how different types of fiscal policy affect profits and , as a result, investment. We find a sizable negative effect of public spending -- and in particular of its...

This paper studies both theoretically and empirically the determinants of group formation and of the degree of participation when the population is heterogeneous, both in terms of income and race or ethnicity. We are especially interested in whether and how much the degree of heterogeneity in...

In an economy with imperfect labor contracts, differences in the distribution of human capital are an independent source of comparative advantage. I study a world economy with two sectors, one where output is produced by teams and another where individuals can work alone. When workers' abilities...