We investigate whether productivity differences explain why some manufacturers sell only to the domestic market while others serve foreign markets through exports and/or FDI. When overseas production offers no cost advantages, our model predicts that investors should be more productive than...

Firm size follows Zipf's Law, a very fat-tailed distribution that implies a few large firms account for a disproportionate share of overall economic activity. This distribution of firm size is crucial for evaluating the welfare impact of economic policies such as barriers to entry or trade...

Many economic decisions involve a binary choice - for example, when consumers decide to purchase a good or when firms decide to enter a new market. In such settings, agents' choices often depend on imperfect expectations of the future payoffs from their decision (expectational error) as well as...

In what order should a developing country adopt policy reforms? Do some policies complement each other? Do others substitute for each other? To address these questions, we develop a two-country dynamic general equilibrium model with entry and exit of firms that are monopolistic competitors. The...

I develop a new theory of marketing costs and introduce it into a model of trade with product differentiation and firm productivity heterogeneity. In this model, a firm enters a market if it makes profits by reaching a single consumer there and pays an increasing marginal cost to access...

We show in a multi-sector, heterogeneous-firm trade model that the effect of tariffs on entry, especially in the presence of production linkages, can reverse the traditional positive optimal tariff argument. We then use a new tariff dataset, and apply it to a 189-country, 15-sector version of...

Exporting firms often enter foreign markets that are similar to previous export destinations. We develop a dynamic model in which a firm's exports in a market may depend on how similar the market is to the firm's home country (gravity) and to its previous export destinations (extended gravity)....

We show that a trade model with an exogenous set of heterogeneous firms with fixed operating costs has the same aggregate outcomes as a span-of-control model. Fixed costs in the heterogeneous-firm model are entrepreneurs' forgone wage in the span-of-control model

The increasing returns revolution in trade is incomplete in an important respect there exists no compelling empirical demonstration of the role of increasing returns in determining production and trade structure. One reason is that trade patterns of the canonical increasing returns models are a...