Abstract not found

We investigate the “generalized second-price ” (GSP) auction, a new mechanism used by search engines to sell online advertising. Although GSP looks similar to the Vickrey-Clarke-Groves (VCG) mechanism, its properties are very different. Unlike the VCG mechanism, GSP generally does not have an equilibrium in dominant strategies, and truth-telling is not an equilibrium of GSP. To analyze the properties of GSP, we describe the generalized English auction that corresponds to GSP and show that it has a unique equilibrium. This is an ex post equilibrium, with the same payoffs to all players as the dominant strategy equilibrium of VCG. (JEL D44, L81, M37) This paper investigates a new auction mechanism, which we call the “generalized secondprice” auction, or GSP. GSP is tailored to the unique environment of the market for online ads, and neither the environment nor the mechanism has previously been studied in the mechanism design literature. While studying the properties of a novel mechanism is often fascinating in itself, our interest is also motivated by the spectacular commercial success of GSP. It is the dominant transaction mechanism in a large and rapidly growing industry. For example, Google’s total revenue in 2005 was $6.14 billion. Over 98 percent of its revenue came from GSP auctions. Yahoo!’s total revenue in 2005 was $5.26 billion. A large share of Yahoo!’s revenue is derived from sales via GSP auctions. It is believed that over half of Yahoo!’s revenue is derived from sales via GSP auctions. As of May 2006, the combined market capitalization of these companies exceeded $150 billion. Let us briefly describe how these auctions work. When an Internet user enters a search

We use simple learning models to track the behavior observed in experiments concerning three extensive form games with similar perfect equilibria. In only two of the games does observed behavior approach the perfect equilibrium as players gain experience. We examine a family of learning models which possess some of the robust properties of learning noted in the psychology literature. The intermediate term predictions of these models track well the observed behavior in all three games, even though the models considered differ in their very long term predictions. We argue that for predicting observed behavior the intermediate term predictions of dynamic learning models may be even more important than their asymptotic properties.

This paper concerns the difficulties associated with establishing a time at which a market will operate. We first describe the experience of several dozen markets and submarkets, from entry-level professional labor markets in the United States, Canada, England, and Japan, to the (American) market for postseason college football bowls. The difficulties these markets have experienced in coordinating the timing of transactions have been decisive in determining how they are organized today. The paper develops a framework in which to address the timing of transactions and the tendency observed in many of these markets for transactions to become earlier and earlier.

this article appeared as Tech. Rep. CSLI-94-188, CSLI, Stanford University

We create an environment in which congestion forces agents to match inefficiently early. We then introduce one of two centralized clearinghouse mechanisms. One of these has been successfully used to halt this kind of unraveling in a number of labor markets, while the other has failed. When it is costly for �rms and workers to be mismatched compared with the costs of matching early, the experimental observations reproduce the �eld observations. Furthermore, the experiment permits us to observe the transition between a decentralized and a centralized market, both when the centralized market fails to control unraveling and when it succeeds, at a level of detail unavailable in �eld data. Field studies of competitive entry-level professional labor markets reveal a common form of market failure involving the ‘‘unraveling’ ’ of hiring decisions, in which employment contracts from year to year become earlier and earlier in advance of employment, even when this becomes very costly {Roth and Xing 1994}. Sometimes the cause is that the market is organized in

The entry-level market for American gastroenterologists was organized by a centralized clearinghouse from 1986 to 1996. Before, and since, it has been conducted via a decentralized market in which appointment dates have unraveled to well over a year before the start of employment. We find that, both before and after the years in which the centralized clearinghouse was used, gastroenterologists are less mobile and more likely to be employed at the same hospital in which they were internal medicine residents than when the clearinghouse was in use. This suggests that the clearinghouse not only coordinates the timing of appointments but also increases the scope of the market, compared to a decentralized market with early appointments.

Abstract not found

In the context of entry-level labor markets, we consider the potential transactions that have to be evaluated before equilibrium transactions can be identified. These potential transactions involve offers that are rejected. After an initial phase in which many offers can be proffered in parallel, subsequent potential transactions must be processed serially, since a new offer cannot be made until an outstanding offer is rejected. In this phase even a small time required to process offers and rejections may cause bottlenecks. In many, perhaps most, decentralized labor markets, this means that transactions have to be finalized before there is time for the market to clear, that is, before all the potential transactions that would need to be evaluated in order to reach a stable outcome can in fact be evaluated. This has implications for the strategic behavior of firms and workers. In particular, in deciding to whom to offer a position, a firm may have strong incentives to consider not only its preferences over workers but also the likelihood that its offer will be accepted, since if its offer is rejected it may find that many other potential employees have become unavailable in the interim. The analysis is carried out in connection with the decentralized

We describe a fixed-point based approach to the theory of bipartite stable matchings. By this, we provide a common framework that links together seemingly distant results, like the stable marriage theorem of Gale and Shapley [11], the Menelsohn-Dulmage theorem [21], the Kundu-Lawler theorem [19], Tarski's fixed point theorem [32], the Cantor-Bernstein theorem, Pym's linking theorem [22, 23] or the monochromatic path theorem of Sands et al. [29]. In this framework, we formulate a matroid-generalization of the stable marriage theorem and study the lattice structure of generalized stable matchings. Based on the theory of lattice polyhedra and blocking polyhedra, we extend results of Vande Vate [33] and Rothblum [28] on the bipartite stable matching polytope.