This paper presents a new method for estimating discrete games based on bounds of conditional choice probabilities. The method does not require solving the game and is scalable to models with many firms and many discrete decisions. We apply the method to study merger effects on firm entry and...

E-commerce sales have grown rapidly worldwide, massively increasing the availability of new products. We examine data from the largest digital platform in China and find that the number of book titles almost doubled, prices fell somewhat, and most new books are sold to consumers with unusual...

We analyze entry, pricing and product design in a model with differentiated products. Under plausible conditions, entry into an initially monopolized market leads to higher prices for some, possibly all, consumers. Entry can induce a misallocation of goods to consumers, segment the market in a...

Product diversity pervades every modern marketplace, and economists have devoted substantial attention to firms' decisions about the supply of variety. This study looks at the consumer's side by discussing the demand for variety. Using the framework of the home-production model, we trace...

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...

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...

This paper investigates how the tying of complementary products can be used to preserve and extend monopoly positions. We first show how a firm that is a monopolist of a product in the current period can use tying to preserve its monopoly position in future periods. We then show using related...

This paper argues that the theoretical foundations for the gravity equation are general, while the empirical performance of the gravity equation is specific to the type of goods examined. Most existing theory for the gravity equation depends on the assumption of differentiated goods. We show...

During the last two decades, new research has greatly advanced our understanding of the structure of world trade. This article reviews the empirical literature that grew out of this effort, emphasizing the ways in which it relied on theoretical developments