Word-Of-Mouth Communication and Community Enforcement

We study a repeated game where a seller, who has a short-term incentive to supply low quality, is periodically matched with a randomly selected buyer. Buyers observe only the outcomes of their neighbors' games and may receive signals from them. When the buyer population is large, the seller may sell high quality even when each buyer observes her action in any given period with an arbitrarily small probability. When networking among buyers is costly, low quality is always supplied with a positive probability. For this case, we characterize an equilibrium where the seller randomizes between high and low quality.     

Liquid markets and competition

A market is liquid if no individual's actions have a big effect on the prices of goods traded in that market. Perfectly competitive markets are therefore perfectly liquid. It is well known that market liquidity can be achieved by increasing the number of traders so that individual trades are small compared to total trades. We show that even when there are only few traders, market liquidity can be achieved through large short sales in which net trades are small relative to gross trades. In particular, for a natural variant of the market game which permits unlimited short sales, we show that there is always a Nash equilibrium allocation arbitrarily close to a competitive equilibrium allocation. Of course, not all NE are near competitive. Only the large-short-sales NE are nearly liquid and hence close to CE.     

Sequential voting with abstention

Dekel and Piccione [2000. Sequential voting procedures in symmetric binary elections. J. Polit. Economy 108, 34–55] have proven that information cascades do not necessarily affect the properties of information aggregation in sequential elections: under standard conditions, any symmetric equilibrium of a simultaneous voting mechanism is also an equilibrium of the correspondent sequential mechanism. We show that when voters can abstain, these results are sensitive to the introduction of an arbitrarily small cost of voting: the set of equilibria in the two mechanisms are generally disjoint; and the informative properties of the equilibrium sets can be ranked. If an appropriate q-rule is chosen, when the cost of voting is small the unique symmetric equilibrium of the simultaneous voting mechanism dominates all equilibria of the sequential mechanism.     

Games with Imperfectly Observable Commitment

[1]claims that, in models of commitment, “the first-mover advantage is eliminated when there is aslightamount of noise associated with the observation of the first-mover's selection.” We show that the validity of this claim depends crucially on the restriction to pure strategy equilibria. The game analyzed by Bagwell always has a mixed equilibrium that is close to the Stackelberg equilibrium when the noise is small. Furthermore, an equilibrium selection theory that combines elements from the theory of[7]with elements from the theory of [6], actually selects this “noisy Stackelberg equilibrium.”Journal of Economic LiteratureClassification Number: C72.     

ON THE ROLE OF TAX SUBSIDY SCHEME IN MONEY SEARCH MODELS*

This article investigates the roles of policy in search models with divisible money. Recently, real indeterminacy of stationary equilibria has been found in both specific and general search models with divisible money. Thus if we assume the divisibility of money, it would be quite difficult to make accurate predictions of the effects of simple monetary policies. Therefore, in this article, we introduce a certain tax subsidy scheme and show that this is effective in selecting a determinate efficient equilibrium. In other words, for a given efficient equilibrium and for any real number δ > 0 , a certain tax subsidy scheme induces a locally determinate equilibrium within the δ‐neighborhood of the given equilibrium. Moreover, the size of the tax subsidy can be arbitrarily small.     

EQUILIBRIUM GROWTH IN A MONETARY ECONOMY WITH TRANSACTIONS COSTS*

The paper describes a dynamic general equilibrium monetary economy with technological primitives that are consistent with the possibility of asymptotic equilibrium growth. The paper focuses on the relationship between equilibrium financing constraints on investment goods, transaction costs and economic growth. A generalized growth condition is derived that involves both monetary growth rates and transaction costs. The condition is used to show that (i) although inflation taxes can potentially exert a negative influence on long-run economic growth, these growth effects cannot in general be arbitrarily large; and (ii) for some monetary growth rates, money is superneutral in contrast to the models of Stockman and Abel. Numerical work indicates that although the welfare and growth effects of decreasing nominal interest rates from a benchmark are large, the costs associated with raising nominal interest rates from benchmark are not.     

Contagion

Each player in an infinite population interacts strategically with a finitesubset of that population. Suppose each player's binary choice in eachperiod is a best response to the population choices of the previous period.When can behaviour that is initially played by only a finite set of playersspread to the whole population? This paper characterizes when such contagionis possible for arbitrary local interaction systems. Maximal contagionoccurs when local interaction is sufficiently uniform and there is lowneighbour growth, i.e. the number of players who can be reached in k steps does not grow exponentially in k .     

Noisy Contagion Without Mutation

In a local interaction game agents play an identical stage game against their neighbours over time. For nearest neighbour interaction, it is established that, starting from a random initial configuration in which each agent has a positive probability of playing the risk dominant strategy, a sufficiently large population coordinates in the long-run on the risk dominant equilibrium almost surely. Our result improves on Blume (1995), Ellison (2000), and Morris (2000) by showing that the risk dominant equilibrium spreads to the entire population in a two dimensional lattice and without the help of mutation, as long as there is some randomness in the initial configuration.     

Risk-sharing and crises. Global games of regime change with endogenous wealth

I add heterogeneous agents and risk-sharing opportunities to a global game of regime change. The novel insight is that when there is a risk-sharing motive, fundamentals drive not only individual behavior, but also select which individuals are more relevant for the likelihood of a crisis because of endogenous shifts in wealth. If attacking is relatively safe, attack behavior in the global game and trade in state-contingent assets feed back into each other. This feedback implies that multiple equilibria may exist even if signal noise becomes arbitrarily small. In addition, heterogeneity in risk-aversion within the population amplifies the influence of the state of the economy on the probability of a crisis.     

Forecasting and combining competing models of exchange rate determination

This article investigates the out-of-sample forecast performance of a set of competing models of exchange rate determination. We compare standard linear models with models that characterize the relationship between exchange rate and the underlying fundamentals by nonlinear dynamics. Linear models tend to outperform at short forecast horizons especially when deviations from long-term equilibrium are small. In contrast, nonlinear models with more elaborate mean-reverting components dominate at longer horizons especially when deviations from long-term equilibrium are large. The results also suggest that combining different forecasting procedures generally produces more accurate forecasts than can be attained from a single model.     

Communication in bargaining over decision rights

This paper develops a model of bargaining over decision rights between an uninformed principal and an informed but self-interested agent. We introduce two different bargaining mechanisms: tacit and explicit bargaining. In tacit bargaining, an uninformed principal makes a take-it-or-leave-it price offer to the agent, who then decides whether to accept or reject the offer. In the equilibrium of the game, the principal inefficiently screens out some agent types so that the agent's private information cannot be fully utilized when the decision is made. In explicit bargaining in which parties can communicate explicitly via cheap talk before tacit bargaining, however, an equilibrium with no such inefficient screening exists even when the conflict of interest is arbitrarily large. We also follow a mechanism design approach, showing that under certain conditions, explicit bargaining is an optimal bargaining mechanism that maximizes the joint surplus of the parties.     

On price taking behavior in a nonrenewable resource cartel–fringe game

We consider a nonrenewable resource game with one cartel and a set of fringe members. We show that (i) the outcomes of the closed-loop and the open-loop nonrenewable resource game with the fringe members as price takers (the cartel–fringe game à la Salant, 1976) coincide and (ii) when the number of fringe firms becomes arbitrarily large, the equilibrium outcome of the closed-loop Nash game does not coincide with the equilibrium outcome of the closed-loop cartel–fringe game. Thus, the outcome of the cartel–fringe open-loop equilibrium can be supported as an outcome of a subgame-perfect equilibrium. However the interpretation of the cartel–fringe model, where from the outset the fringe is assumed to be price taker, as a limit case of an asymmetric oligopoly with the agents playing Nash–Cournot, does not extend to the case where firms can use closed-loop strategies.     

Collusive behaviour in finite repeated games with bonding

In finite repeated games, it is not possible to enforce collusive behaviour using deterrent strategies if the state game has a unique Nash equilibrium, because of the ‘unravelling’ of cooperative behaviour in the last period. This paper demonstrates that under certain conditions, some cooperation among the players can be maintained if they can post a bond which they must forfeit if they defect from the cooperative mode. We show that the incentives to cooperate increase as the period of interaction grows in that the size of the bonds required to deter defection become arbitrarily small as the number of periods in the game increases.     

Informed manipulation

In asymmetric information models of financial markets, prices imperfectly reveal the private information held by traders. Informed insiders thus have an incentive not only to trade less aggressively but also to manipulate the market by trading in the wrong direction and undertaking short-term losses, thereby increasing the noise in the trading process. In this paper we show that when the market faces uncertainty about the existence of the insider in the market and when there is a large number of trading periods before all private information is revealed, long-lived informed traders will manipulate in every equilibrium.     

Learning to Learn, Pattern Recognition, and Nash Equilibrium

The paper studies a large class of bounded-rationality, probabilistic learning models on strategic-form games. The main assumption is that players “recognize” cyclic patterns in the observed history of play. The main result is convergence with probability one to a fixed pattern of pure strategy Nash equilibria, in a large class of “simple games” in which the pure equilibria are nicely spread along the lattice of the game. We also prove that a necessary condition for convergence of behavior to a mixed strategy Nash equilibrium is that the players consider arbitrarily long histories when forming their predictions.Journal of Economic LiteratureClassification Numbers: C72, D83.     

On the strategic impact of an event under non-common priors

This paper studies the impact of a small probability event on strategic behavior in incomplete information games with non-common priors. It is shown that the global impact of a small probability event (i.e., its propensity to affect strategic behavior at all states in the state space) has an upper bound that is an increasing function of a measure of discrepancy from the common prior assumption. In particular, its global impact can be arbitrarily large under non-common priors, but is bounded from above under common priors. These results quantify the different implications common prior and non-common prior models have on the (infinite) hierarchies of beliefs.     

Implementation of individually rational social choice functions with guaranteed utilities

A simple mechanism is presented that allocates an indivisible object between two agents for almost any possible compensation rule. Furthermore, the equilibrium strategy guarantees a level of utility not less than −ε, where ε can be arbitrarily small.     

Large time and small noise asymptotic results for mean reverting diffusion processes with applications

Summary. We use the theory of large deviations to investigate the large time behavior and the small noise asymptotics of random economic processes whose evolutions are governed by mean-reverting stochastic differential equations with (i) constant and (ii) state dependent noise terms. We explicitly show that the probability is exponentially small that the time averages of these process will occupy regions distinct from their stable equilibrium position. We also demonstrate that as the noise parameter decreases, there is an exponential convergence to the stable position. Applications of large deviation techniques and public policy implications of our results for regulators are explored. Received: December 7, 1998; revised version: October 25, 1999     

Retrading in market games

When agents are not price takers, they typically cannot obtain an efficient real location of resources in one round of trade. This paper presents a non-cooperative model of imperfect competition where agents can retrade allocations, consistent with Edgeworth's idea of recontracting. We show (a) there are Pareto optimal allocations, including competitive equilibrium allocations, that can be approximated arbitrarily closely when trade is myopic, i.e., when agents play a static Nash equilibrium at every round of retrading; (b) any converging sequence of allocations generated by myopic retrading can be supported along some retrade-proof subgame perfect equilibrium path when traders anticipate future rounds of trading.