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Uncertainty and Delay in Bargaining

Review of Economic Studies 1990 57(4), 575
This paper investigates the relationship between uncertainty and delay of agreement in the one-sided offer bargaining model with two-sided uncertainty where the seller makes offers. We construct a weak stationary equilibrium in which different types of the seller charge different prices in every period. We completely characterize the separating equilibrium by three regularity conditions, and show that the time interval between offers converges to zero, the seller's initial price offer in a separating equilibrium converges with probability 1 to the lowest valuation of the buyer if and only if the gain from trading is common knowledge.

A Refinement of Sequential Equilibrium

Econometrica 1987 55(6), 1367
The author proposes a refinement of seq uential equilibrium for extensive form games by generalizing a restri ction proposed for signaling games in Cho and D. M. Kreps (1987). The restriction is that beliefs must not assign positive weight to the p ossibilities that can be excluded through reasonable introspection ba sed on the data available as common knowledge. A new technique is dev eloped in order to prove the existence of forward induction equilibri um, which consists of two steps. First, the author establishes the ge neric existence of forward induction equilibrium by exploiting the re sults of E. Kohlberg and J. F. Mertens (1986). Then, he shows that th e forward induction equilibrium correspondence is upper hemicontinuou s in the outcome space with respect to the changes of parameters of t he game. Copyright 1987 by The Econometric Society.

Monotonicity and Rationalizability in a Large First Price Auction

Review of Economic Studies 2005 72(4), 1031-1055
ABSTRACT. This paper proves that the monotonicity of bidding strategies together with the rationality of bidders implies that the winning bid in a first price auction converges to the competitive equilibrium price as the number of bidders increases (Wilson (1977)). Instead of analyzing the symmetric Nash equilibrium, we examine rationalizable strategies (Bernheim (1984) and Pearce (1984)) among the set of monotonic bidding strategies to prove that any monotonic rationalizable bidding strategy must be within a small neighborhood of the “true ” valuation of the object, conditioned on the signal received by the bidder. We obtain an information aggregation result similar to Wilson (1977), while dispensing with almost all symmetric assumptions and using a milder solution concept than the Nash equilibrium. In particular, if every bidder is ex ante identical, then any rationalizable bidding strategy must be within a small neighborhood of the symmetric Nash equilibrium. In a symmetric first price auction, the symmetry of outcomes is implied rather than assumed.

Escaping Nash Inflation

Review of Economic Studies 2002 69(1), 1-40 open access
. Mean dynamics describe the convergence to self-confirming equilibria of selfreferential systems under discounted least squares learning. Escape dynamics recurrently propel away from a self-confirming equilibrium. In a model with a unique self-confirming equilibrium, the escape dynamics make the government discover too strong a version of the natural rate hypothesis. The escape route dynamics cause recurrent outcomes close to the Ramsey (commitment) inflation rate in a model with an adaptive government. Key Words: Self-confirming equilibrium, mean dynamics, escape route, large deviation, natural rate of unemployment, adaptation, experimentation trap. `If an unlikely event occurs, it is very likely to occur in the most likely way.' Michael Harrison 1. INTRODUCTION Building on work by Sims (1988) and Chung (1990), Sargent (1999) showed how a government adaptively fitting an approximating Phillips curve model recurrently sets inflation near the optimal time-inconsistent ouctome, althoug...

Gresham's Law of Model Averaging

American Economic Review 2017 107(11), 3589-3616 open access
A decision maker doubts the stationarity of his environment. In response, he uses two models, one with time-varying parameters, and another with constant parameters. Forecasts are then based on a Bayesian model averaging strategy, which mixes forecasts from the two models. In reality, structural parameters are constant, but the (unknown) true model features expectational feedback, which the reduced-form models neglect. This feedback permits fears of parameter instability to become self-confirming. Within the context of a standard asset-pricing model, we use the tools of large deviations theory to show that even though the constant parameter model would converge to the rational expectations equilibrium if considered in isolation, the mere presence of an unstable alternative drives it out of consideration. (JEL C63, D83, D84)

Signaling Games and Stable Equilibria

Quarterly Journal of Economics 1987 102(2), 179
Games in which one party conveys private information to a second through messages typically admit large numbers of sequential equilibria, as the second party may entertain a wealth of beliefs in response to out-of-equilibrium messages. By restricting those out-of-equilibrium beliefs, one can sometimes eliminate many unintuitive equilibria. We present a number of formal restrictions of this sort, investigate their behavior in specific examples, and relate these restrictions to Kohlberg and Mertens' notion of stability.