When asked to name one proposition in the social sciences that is both true and non-trivial, Paul Samuelson famously replied: ‘Ricardo's theory of comparative advantage’. Truth, however, in Samuelson's reply refers to the fact that Ricardo's theory of comparative advantage is mathematically correct, not that it is empirically valid. In this paper we develop and implement an empirical test of Ricardo's ideas. We use novel agricultural data that describe the productivity in 17 crops of 1.6 million parcels of land in 55 countries around the world. We find that a regression of log observed output on log predicted output has a (precisely estimated) slope of 0.84 and an R-squared of 0.93. In our view, these findings offer considerable support for Ricardo's ideas.

The theory of international trade has paid scant attention to market institutions. Neither neoclassical theory nor new trade models typically specify the process by which supply and demand meet. Yet in the real world, intermediaries play a central role in materializing the gains from exchange outlined by standard trade theories. In Antr’and Costinot (2010), we have developed a stylized but explicit model of intermediation in trade. In this short paper, we present a variant of this model that illustrates the potential role of intermediaries in facilitating the realization of the gains from trade.

We develop a methodology to construct nonparametric counterfactual predictions, free of functional form restrictions on preferences and technology, in neoclassical models of international trade. First, we establish the equivalence between such models and reduced exchange models in which countries directly exchange factor services. This equivalence implies that, for an arbitrary change in trade costs, counterfactual changes in the factor content of trade, factor prices, and welfare only depend on the shape of a reduced factor demand system. Second, we provide sufficient conditions under which estimates of this system can be recovered nonparametrically. Together, these results offer a strict generalization of the parametric approach used in so-called gravity models. Finally, we use China's recent integration into the world economy to illustrate the feasibility and potential benefits of our approach.

A salient feature of globalization in recent decades is the emergence of “global supply chains” in which different countries specialize in different stages of a sequential production process. In Costinot, Vogel and Wang (2011) (CVW hereafter), we have developed a simple theory of trade with sequential production to shed light on how global supply chains affect the interdependence of nations. In this paper we develop a multi-factor extension of CVW to explore how the emergence of global supply chains may affect wage inequality within countries.

Micro-level data have had a profound influence on research in international trade over the last ten years. In many regards, this research agenda has been very successful. New stylized facts have been uncovered and new trade models have been developed to explain these facts. In this paper we investigate to what extent answers to new micro-level questions have affected answers to an old and central question in the field: how large are the welfare gains from trade? A crude summary of our results is: “So far, not much.”