Justifiable preferences

We characterize preferences over acts that can be represented by a utility function and a multiple-prior, such that an act f is preferred to act g if there is a prior under which the expected utility induced by f is higher than that induced by g. These preferences are referred to as justifiable preferences. We further introduce a generalized model of ambiguity that involves a collection of multiple-priors, namely, multiple multiple-priors and incorporate Bewley?s Knightian model in justifiability: f is preferred to g if, according to at least one set of priors, f is unanimously preferred to g.     

Core allocations and the dimension of the cone of efficiency price vectors

Let (R₁,…,R_k) be an arbitrary partition of the grand coalition in an atomless exchange economy with k “large enough.” We prove that an optimal allocation x belongs to the core if and only if x cannot be improved upon by any coalition that includes at least one of the R_i's. K is “large enough” if k ? r + 1, where r is the linear dimension of the cone P of the efficiency price vectors for x. Recall that it is always true that r ? n, when n is the number of commodities in the market, and that under differentiability and interiority r = 1; thus k can be chosen to be 2 (i.e., for any coalition R, an allocation x belongs to the core of the market if and only if x is not blocked by any coalition that either contains R or contains its complement).     

How to gamble against all odds

We compare the power of betting strategies (aka martingales) whose wagers take values in different sets of reals. A martingale whose wagers take values in a set A is called an A-martingale. A set of reals B anticipates a set A, if for every A-martingale there is a countable set of B-martingales, such that on every binary sequence on which the A-martingale gains an infinite amount at least one of the B-martingales gains an infinite amount, too.We show that for two important classes of pairs of sets A and B, B anticipates A if and only if the closure of B contains rA, for some positive r. One class is when A is bounded and B is bounded away from zero; the other class is when B is well ordered. Our results generalize several recent results in algorithmic randomness and answer a question posed by Chalcraft et al. (2012).     

Undominated directions of tax reform

This article considers the reform of a commodity tax system. Consumers' preferences over directions of tax reform are constructed from indirect utility functions. A Wicksellian decision procedure is used to define a dominance relation on the set of directions of change; direction x dominates direction y if and only if (a) everybody prefers x to y or (b) x is the status quo and at least one person prefers x to y. A number of characterizations of undominated directions of change are provided. A related unanimity rule procedure, which does not single out the status quo for special treatment, is also considered. Particular attention is paid to the issue of whether Wicksellian reforms preserve production efficiency. Remarks on the relationship between this work, previous work in optimal taxation theory, and social choice theory are also provided.     

Some remarks on the undersized sample problem in econometrics

This paper discusses three approaches to the problem of undersized samples: the estimable function, the generalized inverse and the principal component method. It turns out that the k-class estimation methods amount to ordinary least squares if use is made of estimable function or generalized inverses. The generalized inverse approach is a special case of the estimable function approach and of the principal component solution.     

Equilibrium among local jurisdictions: toward an integrated treatment of voting and residential choice

In models of local public goods with mobile consumers, existence of equilibrium is problematic. Difficulties with existence of equilibrium that arise in models with discrete locations and in models with voting are compounded when both features are introduced into the same model. We present conditions under which equilibrium exists in a model where freely mobile households choose community of residence and amount of housing consumption, and vote on the level of public goods provision. These conditions involve restrictions on preferences and the technology of public goods supply. At least some of these conditions appear consistent with empirical observations. We discuss the implications of the conditions, and their role in assuring existence of equilibrium. A series of computational examples provide illustrations of the way these conditions interact, and the difficulties that must be confronted if they are to be relaxed.     

On estimating earnings functions for LDCs

A technique is developed for estimating earnings functions from data in which both wage-earners and self-employed persons are included; it is argued that the return to schooling is overestimated if only wage-earners are in the sample. A procedure for simultaneously imputing labor incomes to the self-employed is also developed and carried out with 1971 data for Bangkok, Thailand. The evidence suggests that ceteris paribus the self-employed have labor earnings at least as high as their wage-earning counterparts.     

The Effect of Disagreement on Noncooperative Bargaining

A seemingly mild assumption of the standard alternating offers bargaining model under risk is that the breakdown event is not strictly worse than the worst agreement. When this assumption is relaxed the structure of the equilibrium set of agreements changes in an interesting way. We analyse the effect of disagreement on equilibrium, and relate our result to a class of outside option models. Journal of Economic Literature Classification Number: C78.     

Implementation with partial provability

We extend implementation theory by allowing the social choice function to depend on more than just the preferences of the agents and allowing agents to support their statements with hard evidence. We show that a simple condition on evidence is necessary for the implementation of a social choice function f when the preferences of the agents are state independent and sufficient for implementation for any preferences (including state dependent) with at least three agents if the social planner can perform small monetary transfers beyond those called for by f. If transfers can be large, f can be implemented in a game with perfect information when there are at least two players under a boundedness assumption. For both results, transfers only occur out of equilibrium. The use of evidence enables implementation which is robust in the sense that the planner needs little information about agents? preferences or beliefs and agents need little information about each others? preferences. Our results are robust to evidence forgery at any strictly positive cost.     

Unmediated communication in games with complete and incomplete information

We study the effects of adding unmediated communication to static, finite games of complete and incomplete information. We characterize S^U(G), the set of outcomes of a game G, that are induced by sequential equilibria of cheap talk extensions. A cheap talk extension of G is an extensive-form game in which players communicate before playing G. A reliable mediator is not available and players exchange private or public messages that do not affect directly their payoffs. We first show that if G is a game of complete information with five or more players and rational parameters, then S^U(G) coincides with the set of correlated equilibria of G. Next, we demonstrate that if G is a game of incomplete information with at least five players, rational parameters and full support (i.e., all profiles of types have positive probability), then S^U(G) is equal to the set of communication equilibria of G.     

A wide range no-regret theorem

In a sequential decision problem at any stage a decision maker, based on the history, takes a decision and receives a payoff which depends also on the realized state of nature. A strategy, f, is said to be as good as an alternative strategy g at a sequence of states, if in the long run f does, on average, at least as well as g does. It is shown that for any distribution, μ, over the alternative strategies there is a strategy f which is, at any sequence of states, as good as μ-almost any alternative g.     

CAREER CONCERNS,MATCHING, AND OPTIMAL DISCLOSURE POLICY*

Raiders may suffer from information disadvantage since the current employer is often better informed about his workers' quality. When workers have career concerns and matching influences productivity, the initial employer can strategically disclose information to influence incentives and matching efficiency. Long‐term complete contracts induce full disclosure when raiders are perfectly competitive. The optimal short‐term contract induces full disclosure if raiders are perfectly competitive, and the workers are risk neutral and are not liquidity constrained. These conditions are not only sufficient but also “almost necessary” for full disclosure. Partial disclosure may be optimal if any of these conditions is relaxed.     

Monetary policy with uncertain central bank preferences

This paper considers monetary policy when policy makers’ preferences are private information. I show that in the first period of a two-period term, all policy makers but the least inflation averse inflate less - but respond more to shocks - than if there were no private information. Moderately inflation-averse policy makers may reduce their inflation most. A tendency toward increased conservatism in their second period increases inflation in the first. With T<∞ period terms, inflation depends solely on the policy maker's time left in office. With unchanging preferences and no discounting, inflation is lower the longer he has left.     

Bargaining power and enforcement in credit markets

In a credit market with enforcement constraints, we study the effects of a change in the outside options of a potential defaulter on the terms of the credit contract, as well as on borrower payoffs. The results crucially depend on the allocation of “bargaining power” between the borrower and the lender. We prove that there is a crucial threshold of relative weights such that if the borrower has power that exceeds this threshold, her expected utility must go up whenever her outside options come down. But if the borrower has less power than this threshold, her expected payoff must come down with her outside options. In the former case a deterioration in outside options brought about, say, by better enforcement, must create a Lorenz improvement in state-contingent consumption. In particular, borrower consumption rises in all “bad” states in which loans are taken. In the latter case, in contrast, the borrower's consumption must decline, at least for all the bad states. These disparate findings within a single model permit us to interpret existing literature on credit markets in a unified way.     

企业融资中的银行角色与最优融资契约

本文对企业融资中银行所扮演的角色进行分析,发现银行以债权人身份参与企业融资时,只有当企业的自有资金达到一定数量时银行才会接受契约,但是银行的清算威胁不起作用;当银行以股东角色参与企业融资时,清算威胁会降低企业的道德风险,企业的清算价值与自有资金之间的关系会对企业的融资起到至关重要的作用;当银行以混合角色参与企业融资时,银行的清算威胁仍会起到一定的作用,但是对企业的清算价值具有一定的放松,同时企业与享有股权的银行会产生共谋,损害以债权进行投资的银行的利益,企业的最优努力程度会发生偏离,增加了企业的道德风险.     

Correlated equilibria and sunspots

We examine when “sunspots” (uncertainty that has no influence on endowments, preferences, or technology) can affect equilibrium in a simple two-period, two-commodity, two-class economy. We find that such an effect is possibly only if the signals (random variables) that different agents observe are imperfectly correlated (neither perfectly correlated nor independent) and at least one commodity is a Giffen good. For two special cases we characterize the set of equilibria due to sunspots. We conclude by showing the intimate connection between the sunspot equilibria of our finite horizon model and those of the overlapping generations literature.     

Whose opinion counts? Implementation by sortition

Sortition is the process of selecting decision makers or senators by a lottery. We introduce sortition in implementation theory by augmenting a mechanism with a kleroterion or lottery machine p that selects the senators. An outcome is implemented after consulting only the opinions of the senators. We call the corresponding notion of implementation as “p-implementation”, and provide necessary and sufficient conditions for p-implementation. Our main result is that in “economic” environments, every Nash implementable social choice rule (SCR) is also p-implementable if p selects every quartet of players with positive probability and always selects at least three senators. We apply this result to two kleroteria: “oligarchic democracy” and “random sampling”. In economic environments, every Nash implementable SCR can be implemented by oligarchic democracy of three oligarchs. In economic environments, every Nash implementable SCR can be implemented by randomly selecting four senators.     

Bertrand price competition with differentiated commodities

This develops a general equilibrium, differentiated commodity version of Bertrand price competition. We study two, related market games in which buyers as well as sellers announce both quantities and prices. In the first game, buyers' strategies are artificially restricted. The Nash allocations of this game will be nearly competitive, provided that the commodities supplied by sellers are sufficiently similar. In the second game, the restriction on buyers' strategies is relaxed and a stronger solution criterion, called local perfection, is invoked. The locally perfect equilibria of the unrestricted game coincide the Nash equilibria of the restricted game.     

The relevance of private information in mechanism design

Recent results in mechanism design show that as long as agents have correlated private information and are sufficiently risk neutral, it is possible to design mechanisms that leave agents with arbitrarily small information rents. We show that these full-rent-extraction results hinge on the implicit assumption that the agents’ beliefs uniquely determine their preferences. We present an example of the voluntary provision of a public good in which this assumption is relaxed, and consequently, even in highly correlated environments, if agents’ beliefs do not uniquely determine their preferences, then the extraction of the agents’ entire information rents is impossible.     

Assessing the ecological and economic benefits of a no-take marine reserve

The management of marine resources is often impeded by a lack of models to integrate ecological and economic information on exploited populations. We used available biological and economic data for an overexploited population of the leopard grouper (Mycteroperca rosacea) to study if closing parts of the population to fishing would allow sustainable use and maximum economic benefits. Our results suggest that fishing should be closed in all spawning areas and in at least 50% of the adjacent areas. High non-consumptive benefits would be achieved with large closures because the abundance of the leopard groupers, which is an important attribute for SCUBA divers, would increase. In a no-take reserve, the welfare gains of divers seemingly could compensate for losses incurred by fishers if parts of their fishing grounds are closed. An adaptive management scheme could provide a way to incorporate newly available information into management decisions for the no-take reserve.