This paper surveys recent work on competition in markets in which consumers face costs to switching between competing firms' products, even when all firms' products are functionally identical. I address issues in macroeconomics, international trade and industrial organization: In a market with...

The World Wide Web was originally a totally English-based medium due to its US origin. Although the presence of other languages has steadily risen, content in English is still dominant, which raises a natural question of how bilingualism of consumers of a home country affects production of web...

We propose a general model of monopolistic competition and derive a complete characterization of the market equilibrium based on an Arrow-Pratt measure of concavity of the utility, interpreted as the relative love for variety. When the relative love for variety increases with the consumption...

We develop a model with endogeneity in key features of industrial structure linked to heterogeneous cost structures under Cournot competition. We use the model to explore issues related to cross-country differences in industry structure and the impact of globalization on markups and pricing,...

The pattern of trade observed from firm-product-country data calls for a new generation of models. To address the unexplained variation in the data, we propose a new model of monopolistic competition where varieties enter preferences non-symmetrically, capturing both horizontal and vertical...

This paper provides evidence that learning about demand is an important driver of firms' dynamics. We present a simple model with Bayesian learning in which firms are uncertain about their idiosyncratic demand parameter in each of the markets they serve, and update their beliefs as noisy...

We examine the qualitative and quantitative predictions of a heterogeneous firm model à la Melitz (2003) in the context of the Canada - US Free Trade Agreement (CUSFTA) of 1989. We calibrate our model to the pre-trade liberalization stage, simulate the trade liberalization, and compute the...

Empirical evidence suggests that sectoral export growth decreases exporters' survival probability, whereas non--exporters are unaffected. Models with firm heterogeneity in total factor productivity predict the opposite. To solve this puzzle, we develop a two--factor framework where firms differ...

Large multi-product firms dominate international trade flows. This paper documents new facts about multi-product manufacturing exporters that are not easily reconciled with existing multi-product models. Using novel linked production and export data at the firm-product level, we find that the...

We present a North-South model of international trade in which differentiated products are developed in the North. Sectors are populated by final-good producers who differ in productivity levels. Based on productivity and sectoral characteristics, firms decide whether to integrate into the...