We estimate the economic surplus created by Medicare Advantage under its reformed competitive bidding rules. We use data on the universe of Medicare beneficiaries, and develop a model of plan bidding that accounts for both market power and risk selection. We find that private plans have costs...

The combinatorial clock auction is becoming increasingly popular for large-scale spectrum awards and other uses, replacing more traditional ascending or clock auctions. We describe some surprising properties of the auction, including a wide range of ex post equilibria with demand expansion,...

Search frictions can explain why the "law of one price" fails in retail markets and why even firms selling commodity products have pricing power. In online commerce, physical search costs are low, yet price dispersion is common. We use browsing data from eBay to estimate a model of consumer...

The internet has dramatically reduced the cost of varying prices, dis- plays and information provided to consumers, facilitating both active and passive experimentation. We document the prevalence of targeted pricing and auction design variation on eBay, and identify hundreds of thousands of...

The field of Industrial Organization has made dramatic advances over the last few decades in developing empirical methods for analyzing imperfect competition and the organization of markets. We describe the motivation for these developments and some of the successes. We also discuss the relative...

I present a stochastic version of Tirole's (1996) collective reputation model. In equilibrium, group behavior is persistent due to a complementarity between the group's reputation, which depends on the past behavior of group members, and current incentives. A group can maintain a strong...

We describe factors that make bidding in large spectrum auctions complex including exposure and budget problems, the role of timing within an ascending auction, and the possibilities for price forecasting and how economic and game-theoretic analysis can assist bidders in overcoming these...

Contractual theories of vertical integration derive firm boundaries as an efficient response to market transaction costs. These theories predict a relationship between underlying features of transactions and observed integration decisions. There has been some progress in testing these...

We estimate the sensitivity of Internet retail purchasing to sales taxes using data from the eBay marketplace. Our Örst approach exploits the fact that seller locations are revealed only after buyers have expressed interest in an item by clicking on its listing. We use millions of location...

Demand for wireless data communication has risen rapidly in the past few years, raising important policy questions about how to allocate radio spectrum for this purpose. Historically, the US government has designated some spectrum for licensed use and a smaller but significant amount for...