This paper develops a search-theoretic model of technological change to explain why both patenting and the growth of productivity have remained roughly constant while research employment in the United States has increased by a factor of six over the past four decades. In the model, researchers sample from probability distributions determining the efficiency of potential new production techniques. Technological breakthroughs, resulting in patents, become increasingly hard to find as the level of technology advances. Given certain restrictions on the search distributions, the equilibrium of the model replicates the U.S. time-series pattern of research, patenting, and productivity.

We develop a Ricardian trade model that incorporates realistic geographic features into general equilibrium. It delivers simple structural equations for bilateral trade with parameters relating to absolute advantage, to comparative advantage (promoting trade), and to geographic barriers (resisting it). We estimate the parameters with data on bilateral trade in manufactures, prices, and geography from 19 OECD countries in 1990. We use the model to explore various issues such as the gains from trade, the role of trade in spreading the benefits of new technology, and the effects of tariff reduction. Copyright The Econometric Society 2002.

We develop a parsimonious model of innovation to confront firm‐level evidence. It captures the dynamics of individual heterogeneous firms, describes the behavior of an industry with firm entry and exit, and delivers a general equilibrium model of technological change. While unifying the theoretical analysis of firms, industries, and the aggregate economy, the model yields insights into empirical work on innovating firms. It accounts for the persistence of firms’ R&D investment, the concentration of R&D among incumbents, the link between R&D and patenting, and why R&D as a fraction of revenues is positively correlated with firm productivity but not with firm size or growth.

Customs data reveal the heterogeneity and granularity of relationships among buyers and sellers, showing how more exports to a destination break down into more firms selling there and more buyers per exporter. We develop a quantitative general equilibrium model of firm‐to‐firm matching that builds on this insight to separate the roles of iceberg costs and matching frictions in gravity. In the cross section, we find matching frictions as important as iceberg costs in impeding trade, and more sensitive to distance. Because domestic and imported intermediates compete directly with labor in performing production tasks, our model also fits the heterogeneity of labor shares across French producers. Applying the framework to the 2004 expansion of the European Union, reduced iceberg costs and reduced matching frictions contributed equally to the increase in French exports to the new members. While workers benefited overall, those competing most directly with imports gained less, even losing in some countries entering the EU.

We examine the sales of French manufacturing firms in 113 destinations, including France itself. Several regularities stand out: (i) the number of French firms selling to a market, relative to French market share, increases systematically with market size; (ii) sales distributions are similar across markets of very different size and extent of French participation; (iii) average sales in France rise systematically with selling to less popular markets and to more markets. We adopt a model of firm heterogeneity and export participation which we estimate to match moments of the French data using the method of simulated moments. The results imply that over half the variation across firms in market entry can be attributed to a single dimension of underlying firm heterogeneity: efficiency. Conditional on entry, underlying efficiency accounts for much less of the variation in sales in any given market. We use our results to simulate the effects of a 10 percent counterfactual decline in bilateral trade barriers on French firms. While total French sales rise by around $16 billion (U.S.), sales by the top decile of firms rise by nearly $23 billion (U.S.). Every lower decile experiences a drop in sales, due to selling less at home or exiting altogether.

We examine the entry behavior of producers in different industries in different ex-port markets using a comprehensive dataset of French firms. These data reveal enormous heterogeneity, primarily within industries, in the nature of entry into different markets. Nonetheless, some striking regularities appear both across and within industries. The French data add a new dimension to an emerging empirical literature examining international trade at the level of individual producers. Andrew Bernard and J. Bradford Jensen (1995, 1999), Sofronis Clerides et al. (1998), and Bee Yan Aw et al. (2000), among others, have shown that: (i) exporters are typically in the minority; (ii) they tend to be more productive and larger; (iii) yet they usually export only a small fraction of their output. The findings that most firms do not export while those that do sell most of what they make at home suggest substantial barriers to exporting. Theories of producer export behavior have suggested either standard “iceberg ” costs, e.g., Bernard et al. (2003) or

We develop a dynamic multicountry general equilibrium model to investigate forces acting on the global economy during the Great Recession and ensuing recovery. Our multisector framework accounts completely for countries' trade, investment, production, and GDPs in terms of different sets of shocks. Applying the model to 21 countries, we investigate the 29 percent drop in world trade in manufactures during the period 2008–2009. A shift in final spending away from tradable sectors, largely caused by declines in durables investment efficiency, accounts for most of the collapse in trade relative to GDP. Shocks to trade frictions, productivity, and demand play minor roles.