An efficiency characterization of plurality social choice on simple preference domains

Summary. We consider a model of social choice dealing with the problem of choosing a subset from a set of objects (e.g. candidate selection, membership, and qualification problems). Agents have trichotomous preferences for which objects are partitioned into three indifference classes, goods, bads, and nulls, or dichotomous preferences for which each object is either a good or a bad. We characterize plurality-like social choice rules on the basis of the three main axioms, known as Pareto efficiency, anonymity, and independence.Received: 29 August 2003, Revised: 3 June 2004, JEL Classification Numbers: D70, D71, D72.Biung-Ghi Ju: I am grateful to William Thomson and Jianbo Zhang for their helpful comments and discussions. I also thank Brandon Dupont, the participants in seminars at Iowa State University, University of Kansas, and the Midwest Theory Meeting at University of Notre Dame. I thank an anonymous referee for detailed comments and suggestions that were very helpful in simplifying the proof of Theorem 1 and in revising the paper.     

Candidate stability and probabilistic voting procedures

Summary. We extend the analysis of Dutta, Jackson and Le Breton (Econometrica, 2001) on strategic candidacy to probabilistic environments. For each agenda and each profile of voters preferences over running candidates, a probabilistic voting procedure selects a lottery on the set of running candidates. Assuming that candidates cannot vote, we show that random dictatorships are the only unanimous probabilistic voting procedures that never provide unilateral incentives for the candidates to withdraw their candidacy at any set of potential candidates. More flexible probabilistic voting procedures can be devised if we restrict our attention to the stability of specific sets of potential candidates.Received: 4 February 2003, Revised: 14 September 2004, JEL Classification Numbers: D71, D72.This is a revised version of a chapter of my Ph.D. Dissertation submitted to the Universitat Autónoma de Barcelona. I am indebted to my supervisor Salvador Barberá for his advice and constant support. I am grateful to Dolors Berga and an anonymous referee for their detailed comments and suggestions. I thank José Alcalde, Walter Bossert, Bhaskar Dutta, Lars Ehlers, Jordi Massó, Diego Moreno, Clara Ponsatí, Yves Sprumont, and William Thomson for many helpful comments and discussions. I thank the hospitality of the C.R.D.E. at the Université de Montréal and the Department of Economics of the University of Warwick where parts of this research were conducted. Financial support through Research Grant 1998FI00022 from Comissionat per Universitats i Recerca, Generalitat de Catalunya, Research Project PB98-870 from the Ministerio de Ciencia y Tecnología, and Fundación Barrié de la Maza is gratefully acknowledged.     

Consistent representative democracy

We study axioms which define “representative democracy” in an environment in which agents vote over a finite set of alternatives. We focus on a property that states that whether votes are aggregated directly or indirectly makes no difference. We call this property representative consistency. Representative consistency formalizes the idea that a voting rule should be immune to gerrymandering. We characterize the class of rules satisfying unanimity, anonymity, and representative consistency. We call these rules “partial priority rules.” A partial priority rule can be interpreted as a rule in which each agent can “veto” certain alternatives. We investigate the implications of imposing other axioms to the list specified above. We also study the partial priority rules in the context of specific economic models.     

Growth and income inequality: a canonical model

Summary. We develop an endogenous growth model with elastic labor supply, in which agents differ in their initial endowments of physical capital. In this framework, the growth rate and the distribution of income are jointly determined. The key equilibrating variable is the equilibrium labor supply. It determines the rate of return to capital, which in turn affects both the rate of capital accumulation and the distribution of income across agents. We then examine the impact of various structural shocks on growth and distribution. We find that faster growth is associated with a more unequal, contemporaneous distribution of income, consistent with recent empirical findings.Received: 7 October 2004, Revised: 18 February 2005, JEL Classification Numbers: O17, O40.Cecilia García-Peñalosa: Correspondence toGarcía-Peñalosa would like to acknowledge the financial support received from the Institut d’Economie Publique (IDEP), Marseille. Turnovsky’s research was supported in part by the Castor endowment at the University of Washington. The paper has benefited from seminar presentations at the University of California, Riverside, and the University of Kansas, as well as from the comments of an anonymous referee.     

A model of endogenous political party platforms

Summary. We develop a model of endogenous party platform formation in a multidimensional policy space. Party platforms depend on the composition of the parties primary electorate. The overall social outcome is taken to be a weighted average of party platforms and individuals vote strategically. Equilibrium is defined to obtain when no group of voters can shift the social outcome in its favor by deviating and the party platforms are consistent with their electorate. We provide sufficient conditions for existence of equilibria.Received: 20 November 2002, Revised: 21 August 2003JEL Classification Numbers: D72, C62.Correspondence to: Ignacio Ortuño-OrtínWe thank A. Caplin, S. Chattopadhyay, C. Martinelli and J. D. Moreno-Ternero and two anonymous referees for helpful comments. This research started while Ortuño-Ortín was a visitor in the Department of Economics at NYU; he thanks for the kind hospitality of this institution. F. Marhuenda and I. Ortuño-Ortín gratefully acknowledge financial support from the Spanish Ministry of Science and Technology Project BEC2001-1653 and Project BEC2001-0980, respectively; A. Gomberg gratefully acknowledges the financial support from the Asociación Mexicana de Cultura.     

Strategy-proof risk sharing

We consider risk sharing problems with a single good and a finite number of states. Agents have a common prior and their preferences are represented in the expected utility form and are risk averse. We study efficient and individually rational risk sharing rules satisfying strategy-proofness, the requirement that no one can ever benefit by misrepresenting his preference. When aggregate certainty holds, we show that “fixed price selections” from Walrasian correspondence are the only rules satisfying efficiency, individual rationality, and strategy-proofness. However, when aggregate uncertainty holds, we show that there exists no rule satisfying the three requirements. Moreover, in the two agents case, we show that dictatorial rules are the only efficient and strategy-proof rules. Dropping the common prior assumption in the model, we show that this assumption is necessary and sufficient for the existence of rules satisfying the three main requirements in the two agents and aggregate certainty case.     

Finding a Nash equilibrium in spatial games is an NP-complete problem

Summary. We consider the class of (finite) spatial games. We show that the problem of determining whether there exists a Nash equilibrium in which each player has a payoff of at least k is NP-complete as a function of the number of players.Received: 15 September 2002, Revised: 9 March 2003, JEL Classification Numbers: C72.Correspondence to: H. HallerWe thank a referee for helpful comments. The hospitality of the Institute of Economics, University of Copenhagen, and the Institute for Advanced Studies, Vienna, is gratefully acknowledged by the third author.     

Equivalence of strong and coalition-proof Nash equilibria in games without spillovers

Summary This paper examines the conditions which guarantee that the set of coalition-proof Nash equilibria coincides with the set of strong Nash equilibria in the normal form games withoutspillovers. We find thatpopulation monotonicity properties of the payoff functions, when the payoff of a player changes monotonically when the size of the group of players choosing the same strategy increases, are crucial to obtain the equivalence of these two solution concepts. We identify the classes of games, satisfying population monotonicity properties, which yield the equivalence of the set of coalition-proof Nash equilibria and the set of strong Nash equilibria. We also provide sufficient conditions for the equivalence result even when the population monotonicity assumptions are relaxed.We wish to thank Mamoru Kaneko, Akihiko Matsui, Tomoichi Shinotsuka, Benyamin Shitoviz, Tayfun Sonmez, William Thomson, the participants of the Southeastern Economic Theory Meeting in Charlottesville and the seminars at CORE and University of Tsukuba for useful discussions and comments. Our special thanks due anonymous referee for the suggestion to add a section addressing the issue of existence of a strong Nash equilibrium.     

Campaign spending regulation in a model of redistributive politics

Summary. We consider a model in which parties that differ in perceived valence choose how to allocate electoral promises (money, pork-barrel projects) among voters. The party perceived to be less valent has a greater incentive to “sell out” to a favored minority and completely expropriate a fraction of the electorate. By reducing the difference in perceived valence, campaign-finance regulations may reduce the extent of the expropriation and achieve a more equitable political outcome. We analyze various instruments of campaign-finance regulation from this perspective.Received: 20 Februay 2003, Revised: 25 January 2005, JEL Classification Numbers: D72, H2.Nicolas Sahuguet: Correspondence toWe thank Alessandro Lizzeri, George Mailath, and Andrew Postlewaite for their comments. We also thank the editor Dan Kovenock and an anonymous referee. The second author is grateful to the National Science Foundation for financial support under grant SES-0078870.     

On the generic impossibility of truthful behavior: A simple approach

Summary We provide an elementary proof showing how in economies with an arbitrary number of agents an arbitrary number of public goods and utility functions quasi-linear in money, any efficient and individually rational mechanism is not strategy-proof for any economy satisfying a mild regularity requirement.The authors wish to thank William Thomson, Salvadpr Barberá, José Angel Silva and an anonymous referee for helpful comments. The remaining errors are our exclusive responsibility. Financial support from DGICYT under project PB 91-0756 and the Instituto Valenciano de Investigaciones Económicas is gratefully acknowledged.     

An efficiency characterization of plurality rule in collective choice problems

We consider the problem of selecting alternatives from a set of feasible alternatives over which each agent is endowed with a strict preference. We show that there is one and only one rule that satisfies anonymity, neutrality, efficiency, tops-only, and reinforcement. The rule is known as plurality rule, which selects the alternative(s) most preferred by the largest number of agents. I would like to thank William Thomson for helpful suggestions and discussions. I am grateful to Biung-Ghi Ju, Hyungjun Kim, and Yan-An Hwang for detailed comments. I am also indebted to the Editor and an anonymous referee for valuable suggestions. As usual, I am responsible for any remaining deficiency.     

Imperfect common knowledge and the information value of prices

Summary. When economic agents have diverse private information on the fundamentals of the economy, prices may serve as a poor aggregator of this private information. We examine the information value of prices in a monopolistic competition setting that has become standard in the New Keynesian macroeconomics literature. We show that public information has a disproportionate effect on agents’ decisions, crowds out private information, and thereby has the potential to degrade the information value of prices. This effect is strongest in an economy with keen price competition. Monetary policy must rely on less informative signals of the underlying cost conditions.Received: 6 November 2003, Revised: 19 November 2004 JEL Classification Numbers: E31, E32, E58.This paper supersedes the discussion in the first half of our longer paper that circulated under the title “Public and Private Information in Monetary Policy Models”. We thank Andy Filardo, Marvin Goodfriend, Nobu Kiyotaki, John Moore, Stephen Morris and Lars Svensson for advice and comments at various stages of the project, and to Herakles Polemarchakis, Roko Aliprantis and an anonymous referee for their helpful comments and guidance. The views are those of the authors and do not necessarily represent those of the BIS. The second author acknowledges support from the U.K. ESRC under grant RES 000220450. Correspondence to: H.S. Shin     

Portfolio delegation under short-selling constraints

Summary. In this paper we study delegated portfolio management when the manager’s ability to short-sell is restricted. Contrary to previous results, we show that under moral hazard, linear performance-adjusted contracts do provide portfolio managers with incentives to gather information. We find that the risk-averse manager’s effort is an increasing function of her share in the portfolio’s return. This result affects the risk-averse investor’s choice of contracts. Unlike previous results, the purely risk-sharing contract is now shown to be suboptimal. Using numerical methods we show that under the optimal linear contract, the manager’s share in the portfolio return is higher than what it is under a purely risk sharing contract. Additionally, this deviation is shown to be: (i) increasing in the manager’s risk aversion and (ii) larger for tighter short-selling restrictions. As the constraint is relaxed the deviation converges to zero.Received: 25 July 2002, Revised: 12 December 2004, JEL Classification Numbers: D81, D82, J33.Juan-Pedro Gómez: Correspondence toAn earlier version of the paper was circulated under the title “Providing Managerial Incentives: Do Benchmarks Matter?” We are grateful to an anonymous referee whose comments helped to improve the paper. We also thank comments by Viral Acharya, Alexei Goriaev, Ernst Maug, Kristian Rydqvist, Neil Stoughton, Rangarajan Sundaram, Fernando Zapatero and seminar participants at the 1999 SED meetings in Sardinia, the 1999 Workshop in Mutual Fund Performance at EIASM, Brussels, the 2000 EFA meetings in London, the Bank of Norway, the Stockholm Schools of Economics, the Norwegian School of Management and the 2001 WFA meetings in Tucson. Sharma gratefully acknowledges financial support from the Asociacion Mexicana de Cultura.     

Children Crying at Birthday Parties. Why?

We consider the problem of dividing a non-homogeneous one-dimensional continuum whose endpoints are topologically identified. Examples are the division of a birthday cake, the partition of a circular market, the assignment of sentry duty or medical call. We study the existence of rules satisfying requirements of efficiency, fairness (no-envy), and immunity to misrepresentation of preferences (strategy-proofness). This work, supported by NSF under grant SES. 0214691, was presented at Laval University, at the May 2004 Israeli-Turkish Conference on Economic Design at Bilgi University, at the July 2004 Meeting of the Society for Economic Design at the University of Mallorca, and at the July 2004 Seventh International Meeting of the Society for Social Choice and Welfare at Osaka University. I thank Julius Barbanel, Steven Brams, Youngsub Chun, Bettina Klaus, Toyotaka Sakai, and Chun-Hsien Yeh for their comments.     

A short proof of the Bulow-Klemperer auctions vs. negotiations result

Summary. Bulow and Klemperer [1] have provided an upper bound on the value of bargaining power for a seller of an indivisible object. Specifically, negotiating optimally with N buyers yields lower revenue than an English auction with N + 1 buyers. In this paper, a short and intuitive proof of this result is presented.Received: 2 August 2004, Revised: 6 December 2004, JEL Classification Numbers: C78, D44, D82.I would like to thank Per B. Overgaard and an anonymous referee for many valuable comments.     

Interest rate rules, inflation and the Taylor principle: an analytical exploration

Summary. The purpose of this article is to characterize optimal interest rate rules in the framework of a dynamic stochastic general equilibrium model, and notably to scrutinize the “Taylor principle”, according to which the nominal interest rate should respond more than one for one to inflation. This model yields explicit solutions for the optimal rule. We find that the elasticity of response depends on numerous factors, such as the degree of price rigidity, the autocorrelation of the underlying shocks, or which measure of inflation is used. In general the optimal elasticity of the interest rate with respect to inflation needs not be greater than one.Received: 6 November 2003, Revised: 17 August 2004 JEL Classification Numbers: E5, E52, E58.J.-P. Bénassy: I wish to thank Daniel Laskar and an anonymous referee for their perceptive comments on earlier drafts of this paper. Of course all remaining deficiencies are mine.     

A characterization of egalitarian equivalence

Summary Consider a solution (an allocation rule) for an economy which satisfies the following criteria: (1) Pareto efficiency, (2) monotonicity, in the sense that if the set of attainable allocations of the economy becomes larger then the solution makes no consumer worse-off, (3) a weak and primitive notion of fairness with respect to some commodity, say commodityh, in the sense that in an exchange economy in which the aggregate endowment consists only of commodityh, the solution is equal division. We show that in the class of economies which includes non-convex technologies the only such solution is egalitarian equivalence with respect to commodityh. It is also shown that this characterization of egalitarian equivalence holds in convex exchange economies if we add a weak version of a positive association requirement.We are grateful to William Thomson and three anonymous referees for extensive comments on an earlier version. We also acknowledge helpful comments of the participants of the Social Choice and Welfare Conference held in Caen, June 1992.     

Fair social orderings

In a model of private good allocation, we construct social orderings which depend only on ordinal non-comparable information about individual preferences. In order to avoid Arrovian-type impossibilities, we let those social preferences take account of the shape of individual indifference curves. This allows us to introduce equity and cross-economy robustness properties, inspired by the theory of fair allocation. Combining such properties, we characterize two families of fair social orderings. We thank E. Maskin, A. Sen, W. Thomson, B. Tungodden and an anonymous referee for comments, and seminar participants at the Indian Statistical Institute-Delhi, the Norwegian School of Economics (Bergen), the University of Caen, the University of Rochester, and the University of Cergy-Pontoise. Financial Support from European TMR Network Living Standards, Inequality and Taxation Contract ERBFMXCT 980248 is gratefully acknowledged.