Theory predicts that in markets with increasing returns, the number of differentiated products and resulting consumer satisfaction grow in market size. We document this phenomenon across 246 US radio markets. By a mechanism that we term 'preference externalities', an increase in the size of the...

Since the mid-1980s many authors have investigated the influence of information technology (IT) on productivity. Until recently there has been no clear evidence that productivity increases as a result of IT spending. This productivity paradox is partly due to the difficulty in correctly...

Free entry into markets with decreasing average costs and differentiated products can result in an inefficient number of firms and suboptimal product variety. Because new firms and products draw their customers in part from existing products, concentration can affect incentives to enter as well...

As search frictions become smaller in the market for a consumer product, buyers are able to locate and access more sellers per unit of time. In response, sellers choose to design varieties of the product that are more specialized in order to exploit differences in the buyers' preferences. I find...

We use the structure of the Melitz (2003) model to compare the cost of living and welfare across countries, while incorporating product variety measured by the count of barcodes or firms. For 47 countries, we compare welfare relative to the United States to conventional measures of real...

This is an invited chapter for the forthcoming Volume 4 of the Handbook of Industrial Organization. We present empirical models of demand and supply in differentiated products industries with an emphasis on the key ideas arising from the recent applied literature. We start with a discussion of...

We consider a version of the imperfect competition model of Butters (1977), Varian (1980) and Burdett and Judd (1983) in which sellers make an ex-ante investment in the quality of their variety of the product. Equilibrium exists, is unique and is efficient. In equilibrium, search frictions not...

Motivated by the long-standing debate on the pros and cons of competitive devaluation, we propose a new perspective on how monetary and exchange rate policies can contribute to a country's international competitiveness. We refocus the analysis on the implications of monetary stabilization for a...

A recent literature considers the identification of heterogeneous demand and supply models via "quasi-experimental'' variation, as from instrumental variables. In this paper we establish nonparametric identification of differentiated products demand when one has "micro data'' linking...

This paper develops a new method for estimating production-function parameters that can be applied in differentiated-product industries with endogenous quality and variety choice. We take advantage of data on physical quantities of outputs and inputs from the Colombian manufacturing survey,...