Alvin E. Roth

"A Nobel laureate reveals the often surprising rules that govern a vast array of activities -- both mundane and life-changing -- in which money may play little or no role. If you've ever sought a job or hired someone, applied to college or guided your child into a good kindergarten, asked someone out on a date or been asked out, you've participated in a kind of market. Most of the study of economics deals with commodity markets, where the price of a good connects sellers and buyers. But what about other kinds of "goods," like a spot in the Yale freshman class or a position at Google? This is the territory of matching markets, where "sellers" and "buyers" must choose each other, and price isn't the only factor determining who gets what. Alvin E. Roth is one of the world's leading experts on matching markets. He has even designed several of them, including the exchange that places medical students in residencies and the system that increases the number of kidney transplants by better matching donors to patients. In Who Gets What -- And Why, Roth reveals the matching markets hidden around us and shows how to recognize a good match and make smarter, more confident decisions"--

This book, which comprises eight chapters, presents a comprehensive critical survey of the results and methods of laboratory experiments in economics. The first chapter provides an introduction to experimental economics as a whole, while the remaining chapters provide surveys by leading practitioners in areas of economics that have seen a concentration of experiments: public goods, coordination problems, bargaining, industrial organization, asset markets, auctions, and individual decision making. The work aims both to help specialists set an agenda for future research and to provide nonspecialists with a critical review of work completed to date. Its focus is on elucidating the role of experimental studies as a progressive research tool so that, whenever possible, the emphasis is on looking at a series of experiments that build on one another. The contributors to the volume - Colin Camerer, Charles A. Holt, John H. Kagel, John O. Ledyard, Jack Ochs, Alvin E. Roth, and Shyam Sunder - adopt a particular methodological point of view: the way to learn how to design and conduct experiments is to consider how good experiments grow organically out of the issues and hypotheses they are designed to investigate.

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 number of labor market clearinghouses around the world, and have recently been implemented in school choice systems in Boston and New York City. In addition, the study of markets that have failed in ways that can be fixed with centralized mechanisms has led to a deeper understanding of some of the tasks a marketplace needs to accomplish to perform well. In particular, marketplaces work well when they provide thickness to the market, help it deal with the congestion that thickness can bring, and make it safe for participants to act effectively on their preferences. Centralized clearinghouses organized around the deferred acceptance algorithm can have these properties, and this has sometimes allowed failed markets to be reorganized.

"Patients needing kidney transplants may have willing donors who cannot donate to them because of blood or tissue incompatibility. Incompatible patient-donor pairs can exchange donor kidneys with other such pairs. The situation facing such pairs resembles models of the "double coincidence of wants," and relatively few exchanges have been consummated by decentralized means. As the population of available patient-donor pairs grows, the frequency with which exchanges can be arranged will depend in part on how exchanges are organized. We study the potential frequency of exchanges as a function of the number of patient-donor pairs, and the size of the largest feasible exchange. Developing infrastructure to identify and perform 3-way as well as 2-way exchanges will have a substantial effect on the number of transplants, and will help the most vulnerable patients. Larger than 3-way exchanges have much smaller impact. Larger populations of patient-donor pairs increase the percentage of patients of all kinds who can find exchanges"--National Bureau of Economic Research web site.

"In connection with an earlier paper on the exchange of live donor kidneys (Roth, Sonmez, and Unver 2004) the authors entered into discussions with New England transplant surgeons and their colleagues in the transplant community, aimed at implementing a Kidney Exchange program. In the course of those discussions it became clear that a likely first step will be to implement pairwise exchanges, between just two patient-donor pairs, as these are logistically simpler than exchanges involving more than two pairs. Furthermore, the experience of these surgeons suggests to them that patient and surgeon preferences over kidneys should be 0-1, i.e. that patients and surgeons should be indifferent among kidneys from healthy donors whose kidneys are compatible with the patient. This is because, in the United States, transplants of compatible live kidneys have about equal graft survival probabilities, regardless of the closeness of tissue types between patient and donor (unless there is a rare perfect match). In the present paper we show that, although the pairwise constraint eliminates some potential exchanges, there is a wide class of constrained-efficient mechanisms that are strategy-proof when patient-donor pairs and surgeons have 0-1 preferences. This class of mechanisms includes deterministic mechanisms that would accomodate the kinds of priority setting that organ banks currently use for the allocation of cadaver organs, as well as stochastic mechanisms that allow considerations of distributive justice to be addressed"--National Bureau of Economic Research web site.