The Limits of Trust in Economic Transactions - Investigations of Perfect Reputation Systems

nonetrust, reputation systems, eBay

How do coalitions get built - Evidence from an extensive form coalition game with renegotiation & externalities

We investigate a three-person coalition game in which one bargainer, the builder, can propose and build a coalition over two stages. In equilibrium, coalition building ends with an efficient grand coalition, while the equilibrium path is contingent on the values of the two-person coalitions and associated externality payoffs. Considering relative payoffs need not change the equilibrium path. Nevertheless, outcomes in the experiment are often inefficient. One explanation is that bargainers have difficulties anticipating the future actions of other bargainers. This problem might be mitigated by allowing bargainers to communicate prior to each stage. A test finds that communication does in fact increase efficiency, although unevenly, and at the cost of the builder. The study implies that the nature and pattern of communication among bargainers is a critical factor in efficient coalition building.coalitional bargaining, communication, game theory, experiment

Testing and Modeling Fairness Motives

The advent of laboratory experiments in economics over the last few decades has produced an enormous literature devoted to describing, testing and modeling economic and social behavior. Measured by publications and citations, the development of social preference models to capture decisions motivated by fairness and other social criteria, is one of the success stories in this literature. But with this success, and maybe even because of it, controversies have arisen about what the models can and cannot do. In this note, we comment on some of these debates. Our main theme is that descriptive models of behavior should be judged with respect to their usefulness. This is often neglected, partly because there are no accepted measures and tests for the usefulness of a model, while standard procedures to test whether a model is true are readily available. A model that does not capture a 'grain of truth' is unlikely to be useful; however, the relationship is not monotonic in that a 'truer' model is not necessarily a more useful model.experimental economics, fairness, behavioral economics, methodology, usefulness

Does Laboratory Trading Mirror Behavior in Real World Markets? Fair Bargaining and Competitive Bidding on EBay

We conducted a controlled field experiment on eBay and examined to what extent both social and competitive laboratory behavior is robust to institutionally complex real world markets with experienced traders, who selected themselves into these markets. EBay’s natural trading system provides bridges between lab and field environment that can be exploited to explore differences in behavior in the two environments. We find that many sellers do not make use of their commitment power as predicted by standard theories of both selfish and social behavior. However, a concern for equity strongly affects outcomes and reputation building in bilateral bargaining, while buyer competition effectively masks this concern and robustly yields equilibrium outcomes. The dichotomy of behaviors mirrors observations in laboratory research. Furthermore, we find that behavioral patterns in the field experiment mirror fully naturally occurring trading patterns in the market.eBay, auctions, behavioral economics, trust, market design

Information Value and Externalities in Reputation Building - An Experimental Study

In sequential equilibrium theory, reputation building is independent of whether the reputation builder is matched with one long-run player or a series of short run players. We observe, however, that reputation builders are significantly more challenged by long-run players in both laboratory chain store and buyer-seller games. Reputation builder behavior is not as unpredictable as required by the mixed equilibrium strategies and so information about the reputation builder’s past behavior has more economic value than equilibrium predicts. This in turn creates more incentives for long-run players to challenge the reputation builder, because they internalize the information externalities from the continuation game.