Because no marketplace operates in isolation from the larger world, marketplace designs may need to adapt to changes in the larger environments. I discuss such changes in connection with the labor markets for new doctors, new Ph.D. economists, and for kidney exchange transplants. But while...

Many patients in need of a kidney transplant have a willing but incompatible (or poorly matched) living donor. Kidney exchange programs arrange exchanges among such patient-donor pairs, in cycles and chains of exchange, so each patient receives a compatible kidney. Kidney exchange has become a...

We study a model of social learning and communication using hard anecdotal evidence. There are two Bayesian agents (a sender and a receiver) who wish to communicate. The receiver must take an action whose payoff depends on their personal preferences and an unknown state of the world. The sender...

This note describes the unraveling of transaction dates in several markets, including the labor markets for new lawyers hired by large law firms and for gastroenterology fellows, and the market for post-season college football bowls. Together these will illustrate that unraveling can occur in...

This essay discusses some things we have learned about markets, in the process of designing marketplaces to fix market failures. To work well, marketplaces have to provide thickness, i.e. they need to attract a large enough proportion of the potential participants in the market; they have to...

The deferred acceptance algorithm proposed by Gale and Shapley (1962) has had a profound influence on market design, both directly, by being adapted into practical matching mechanisms, and, indirectly, by raising new theoretical questions. Deferred acceptance algorithms are at the basis of a...

This essay examines how repugnance sometimes constrains what transactions and markets we see. When my colleagues and I have helped design markets and allocation procedures, we have often found that distaste for certain kinds of transactions is a real constraint, every bit as real as the...

This paper develops a measure of segregation based on two premises: (1) a measure of segregation should disaggregate to the level of individuals, and (2) an individual is more segregated the more segregated are the agents with whom she interacts. Developing three desirable axioms that any...

There is a great deal of late bidding on internet second price auctions. We show that this need not result from either common value properties of the objects being sold, or irrational behavior: late bidding can occur at equilibrium even in private value auctions. The reason is that very late...

We report on the design of the new clearinghouse adopted by the National Resident Matching Program, which annually fills approximately 20,000 jobs for new physicians in the United States. Because that market exhibits many complementarities between applicants and between positions, the theory of...