
on Collective DecisionMaking 
Issue of 2007‒11‒24
sixteen papers chosen by 
By:  Vincent Anesi (Kennedy School of Government, Harvard University) 
Abstract:  This note studies the noncooperative foundations of von Neumann Morgenstern (vNM) stable sets in voting games. To do so, we study Markov perfect equilibria of a noncooperative legislative bargaining game, based on underlying simple games. The following result emerges from such an exercise: Every stable set of the underlying simple game is the limit set of undominated Markov perfect equilibria of the bargaining game, which form a strategically stable set of equilibria, when voters are suciently farsighted; thus establishing a relationship between vNM stability and strategic stability in voting games. 
Keywords:  Legislative bargaining, committee, strategic stability, stable set. 
JEL:  C71 C78 D71 
Date:  2007–11 
URL:  http://d.repec.org/n?u=RePEc:cdx:dpaper:200709&r=cdm 
By:  Herings P. JeanJacques; Predtetchinski Arkadi (METEOR) 
Abstract:  We study a process of bargaining over social outcomes represented by points in theunit interval. The identity of the proposer is determined by a general Markov process and the acceptance of a proposal requires the approval of it by all the players. We show that for every value of the discount factor below one the subgame perfect equilibrium in stationary strategies is essentially unique and equal to what we call the bargaining equilibrium. We provide a general characterization of the bargaining equilibrium. We consider next the asymptotic behavior of the equilibrium proposals when the discount factor approaches one. We give a complete characterization of the limit of the equilibrium proposals. We show that the limit equilibrium proposals of all the players are the same if the proposer selection process satisfies an irreducibility condition, or more generally, has a unique absorbing set. In general, the limit equilibrium proposals depend on the partition of the set of players in absorbing sets and transient states of the proposer selection process. We fully characterize the limit equilibrium proposals as the unique generalized fixed point of a particular function.This function depends in a simple way on the stationary distribution related to the proposer selection process. We compare the proposal selected according to our bargaining model to the one corresponding to the median voter theorem. 
Keywords:  microeconomics ; 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:dgr:umamet:2007044&r=cdm 
By:  Aziz, Haris (Computer Science Department, University of Warwick); Paterson, Mike (Computer Science Department, University of Warwick); Leech, Dennis (Economics Department, University of Warwick) 
Abstract:  Weighted voting games are ubiquitous mathematical models which are used in economics, political science, neuroscience, threshold logic, reliability theory and distributed systems. They model situations where agents with variable voting weight vote in favour of or against a decision. A coalition of agents is winning if and only if the sum of weights of the coalition exceeds or equals a specified quota. We provide a mathematical and computational characterization of multiple weighted voting games which are an extension of weighted voting games1. We analyse the structure of multiple weighted voting games and some of their combinatorial properties especially with respect to dictatorship, veto power, dummy players and Banzhaf indices. Among other results we extend the concept of amplitude to multiple weighted voting games. An illustrative Mathematica program to compute voting power properties of multiple weighted voting games is also provided. 
Keywords:  multiagent systems ; multiple weighted ; voting games ; game theory, algorithms and ; complexity ; voting power. 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:wrk:warwec:823&r=cdm 
By:  Ehlers Lars; Storcken Ton (METEOR) 
Abstract:  In onedimensional environments with singlepeaked preferences we consider social welfare functions satisfying Arrow''s requirements, i.e. weak Pareto and independence of irrelevant alternatives. When the policy space is a onedimensional continuum such a welfare function is determined by a collection of 2N strictly quasiconcave preferences and a tiebreaking rule. As a corollary we obtain that when the number of voters is odd, simple majority voting is transitive if and only if each voters preference is strictly quasiconcave. 
Keywords:  mathematical economics; 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:dgr:umamet:2007043&r=cdm 
By:  James Albrecht (Georgetown University and IZA); Axel Anderson (Georgetown University); Susan Vroman (Georgetown University and IZA) 
Abstract:  We consider the problem of sequential search when the decision to stop searching is made by a committee. We show that a symmetric stationary equilibrium exists and is unique given that the distribution of rewards is log concave. Committee members set a lower acceptance threshold than do singleagent searchers. In addition, mean preserving spreads in the distribution of rewards may lower each member's continuation value  an impossibility in the singleagent setting. If committee members are very patient or very impatient, expected search duration is lower than it would be for a single agent, but, for intermediate levels of patience, this comparison may be reversed. Holding the fraction of votes required to stop fixed, expected search duration rises with committee size on patient committees but falls with committee size on impatient committees. Finally, we consider the effect of varying the number of votes required to stop, holding committee size constant. We show that the welfaremaximizing vote threshold increases in the rate of patience and that there is a finite bound on patience such that unanimity is welfare maximizing. 
Keywords:  sequential search, voting 
JEL:  D72 D83 
Date:  2007–11 
URL:  http://d.repec.org/n?u=RePEc:iza:izadps:dp3137&r=cdm 
By:  Sanjit Dhami; Ali alNowaihi 
Abstract:  This paper studies the impact of the governance of a group, whether be it unanimity, simple majority or qualified majority, on its size, composition, and inclination to change the status quo. Somewhat surprisingly, we show that not only unanimity might favor the formation of larger groups than majority, but also a change of status quo. This paper therefore suggests that unanimity, often blamed for the European inertia of the last two decades, was only a scapegoat. 
Keywords:  Redistribution; other regarding preferences; single crossing property 
JEL:  D64 D72 D78 
Date:  2007–11 
URL:  http://d.repec.org/n?u=RePEc:lec:leecon:07/16&r=cdm 
By:  Predtetchinski Arkadi (METEOR) 
Abstract:  We study a model of multilateral bargaining over social outcomes represented by points in the unit interval. An acceptance or rejection of a proposal is determined by a voting rule as represented by a collection of decisive coalitions. The focus of the paper is on the asymptotic behavior of subgame perfect equilibria in stationary strategies as the discount factor goes to one. We show that, along any sequence of stationary subgame perfect equilibria, as the discount factor goes to one, the social acceptance set collapses to a point. This point, called the bargaining outcome, is independent of the sequence of equilibria and is uniquely determined by the set of players, the utility functions, the recognition probabilities, and the voting rule. The central result of the paper is a characterization of the bargaining outcome as a unique zero of the characteristic equation. 
Keywords:  microeconomics ; 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:dgr:umamet:2007045&r=cdm 
By:  Ehlers Lars; Storcken Ton (METEOR) 
Abstract:  In spatial environments we consider social welfare functions satisfying Arrow''s requirements, i.e. weak Pareto and independence of irrelevant alternatives. Individual preferences measure distances between alternatives according to the Lpnorm (for a fixed p > 1). When the policy space is multidimensional and the set of alternatives has a nonempty interior and it is compact and convex, any quasitransitive welfare function must be oligarchic. As a corollary we obtain that for transitive welfare functions weak Pareto, independence of irrelevant alternatives, and nondictatorship are inconsistent if the set of alternatives has a nonempty interior and it is compact and convex. 
Keywords:  mathematical economics; 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:dgr:umamet:2007042&r=cdm 
By:  Bochet Olivier; Klaus Bettina (METEOR) 
Abstract:  We discuss a problem concerning Dasgupta, Hammond, and Maskin''s (1979) definition of a rich domain and a very wellknown result they established for these domains: on rich domains, if a social choice function is implementable in Nash strategies, then it is truthfully implementable in dominant strategies Dasgupta, Hammond, and Maskin''s (1979, Theorem 7.2.3). This result is cited many times in later papers, e.g., Laffont and MaskinL(1982, Theorem 4) and Maskin (1985, Theorem 7). Dasgupta, Hammond, and Maskin''s (1979) proof of this result essentially is based on showing that (Maskin) monotonicity implies strategyproofness (or equivalently independent personbyperson monotonicity IPM).In the sequel we abbreviate Dasgupta, Hammond, and Maskin (1979) by DHM. We describe DHM''s model in Section 2.In Section 3 we first construct an example of a DHM rich domain and a social choice function that is monotonic but not strategyproof (Example 1). This suggests that DHM''s rich domain definition is not sufficient to show that monotonicity implies strategyproofness (or that Nash implementability implies truthful implementability in dominant strategies). We then investigate which step in DHM''s proof is problematic  since DHM do not give a direct proof of the result, we reproduce Maskin’s (1985) proof. In Section 4, we consider the presentation of Dasgupta, Hammond, and Maskin''s (1979) definition of a rich domain in the Maskin and Sjöström (2002). It turns out that there definition of a rich domain is different from DHM''s original definition. With this adjusted richness condition the proof that monotonicity implies strategyproofness is correct. 
Keywords:  Economics ; 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:dgr:umamet:2007041&r=cdm 
By:  Dietrich Franz; List Christian (METEOR) 
Abstract:  We consider the classical problem of opinion pooling: the probability assignments of different individuals are to be merged into collective probability assignments. While opinion pooling has been explored in some depth in the literature (by statisticians, economists, and philosophers), all contributions so far assume that the set of relevant events (the "agenda") forms an algebra. However, the disjunction (union) or conjunction (intersection) of two relevant events need not be relevant in practice: it may well be relevant whether it rains, and relevant whether we are happy, but irrelevant whether the disjunction or conjunction of these two events holds. We explore opinion pooling without assuming that the agenda of relevant events forms an algebra. We show that, for a broad class of agendas (whose events may be much less interconnected than those of an algebra), any opinion pooling operator with two properties must be linear, i.e. derive the collective probability of each relevant event as a weighted linear average of the individuals'' probabilities of the event where the weights are eventindependent. For an even broader class of agendas  "nearly" all agendas  we obtain a weaker conclusion: the pooling operator must be neutral, i.e. derive the collective probability of each relevant event as some (possibly nonlinear) function of the individuals'' probabilities of the event where the function is eventindependent. 
Keywords:  mathematical economics; 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:dgr:umamet:2007038&r=cdm 
By:  Hartogh, Matthew 
Abstract:  Abstract: The question posed is whether proposition 209 unconstitutionally bars a remedy to discrimination against a specified group "women and minorities", and thereby denies equal protection of the laws to a targeted group. The partial template for this problem is provided by the Supreme Court’s disposition of Romer v. Evans. The conclusion of my analysis here is that it does not. My analysis relies on two theories, one formal and one political. The formal proposition is this: a remedy is only meaningful as a response to an injury. In equal protection and discrimination jurisprudence, the Federal courts have imposed, and the Supreme Court has upheld, quotas, busing, and other affirmative measures against discrimination where there has been a judicial finding of past discrimination. There has been no such finding against the University of California or any of the contracting agencies of the state of California. Further, each time such a remedy to a demonstrated injury has been imposed, the Court has demanded that the remedy conform to a tight fit to the demonstrated injury. No injury has been demonstrated here, therefore no remedy exists, and to quote Chief Justice Marshall in McCulloch vs. Maryland "what does not exist can not be taken away." 
Keywords:  economics law discrimination game theory welfare 
JEL:  K2 K13 
Date:  2007–01–01 
URL:  http://d.repec.org/n?u=RePEc:pra:mprapa:5774&r=cdm 
By:  Delhaye Eef (K.U.LeuvenCenter for Economic Studies; K.U.LeuvenCenter for Economic Studies); Rousseau Sandra (K.U.LeuvenCenter for Economic Studies) 
Abstract:  According to Becker (1968) it is best to use very high fines and low inspection probabilities to deter traffic accidents because inspection is costly. This paper uses a political economy model to analyse the choice of the fine and the inspection probability. There are two lobby groups: the vulnerable road users and the ‘strong’ road users. If only vulnerable road users are effective in lobbying, we find that the expected fine is higher than if only the interests of car drivers are taken into account. When we consider the choice between inspection probability and the magnitude of the fine for a given expected fine, we find that the fine preferred by the vulnerable road users is higher than socially optimal. The reverse holds if only the car drivers are effective lobbyists. The orders of magnitude are illustrated numerically for speeding and contrasted with current fines for drunk driving in the European Union. 
Keywords:  Political economy, enforcement, traffic safe 
Date:  2007–05 
URL:  http://d.repec.org/n?u=RePEc:ete:etewps:ete0702&r=cdm 
By:  Melanie Lührmann (Institute for Fiscal Studies); Jürgen Maurer (Institute for Fiscal Studies) 
Abstract:  <p><p><p><p><p><p>Decision processes among couples depend on the balance of power between the partners, determining the welfare of household members as well as household outcomes. However, little is known about the determinants of power. The collective model of household behavior gives an operational definition of decision power. We argue that important aspects of this concept of power are measurable through selfassessments of partners' say. Using such a measure, we model balance of power as an outcome of the interplay between both partners' demographic,socioeconomic, and health characteristics. Advancing flexible, yet parsimonious empirical models is crucial for the analysis, as both absolute status as well as relative position in the couple might potentially affect the balance of power, and genderasymmetries may be important. Appropriately, we advance semiparametric double index models that feature one separate index for each spouse, which interact nonparametrically in the determination of power.Based on data from the Mexican Health and Aging Study (MHAS), we find education and employment status to be associated with more individual decision power,especially for women. Moreover, health and income have independent effects on the distribution of power. We also show that contextual factors are important determinants of decision power, with women in urban couples featuring more decision power than their rural counterparts.</p></p></p></p></p></p> 
JEL:  D13 J14 C14 
Date:  2007–10 
URL:  http://d.repec.org/n?u=RePEc:ifs:cemmap:25/07&r=cdm 
By:  Bruckner, Markus; Ciccone, Antonio 
Abstract:  Are civil wars partly caused by low economic growth? And do democratic institutions attenuate the impact of low growth on the likelihood of civil war? Our approach to answering these questions exploits that international commodity prices have a significant effect on income growth in SubSaharan African countries. We show that lower income growth makes civil war more likely in nondemocracies. This effect is significantly weaker in democracies. So much so, that we do not find a link between growth and civil war in countries with democratic institutions. Our results therefore point to an interaction between economic and institutional causes of civil war. 
Keywords:  civil war; Commodity prices; growth; rainfall 
JEL:  O0 P0 Q0 
Date:  2007–11 
URL:  http://d.repec.org/n?u=RePEc:cpr:ceprdp:6568&r=cdm 
By:  Brams, Steven J.; Kilgour, D. Marc 
Abstract:  Three models are presented in which two players agree to share power in a particular ratio, but either player may subsequently “fire” at the other, as in a duel, to try to eliminate it. The players have positive probabilities of eliminating each other by firing. If neither is successful, the agreement stays in place; if one is successful, that player obtains all the power; if each eliminates the other, both players get nothing. In Model I, the game is played once, and in Model II it is repeated, with discounting of future payoffs. Although there are conditions under which each player would prefer not to shoot, satisfying these conditions for one player precludes satisfying them for the other, so at least one player will always have an incentive to shoot. In anticipation, its rival would prefer to shoot, too, so there will be a race to preempt. In Model III, a damage factor caused by shooting, whether successful or not, is introduced into Model II. This mitigates the incentive to shoot but does not eliminate it entirely. The application of the models to conflicts, especially civil wars, is discussed. 
Keywords:  power sharing; repeated game; duel; civil wars 
JEL:  D74 C72 
Date:  2007–01 
URL:  http://d.repec.org/n?u=RePEc:pra:mprapa:5769&r=cdm 
By:  Guido Friebel (Toulouse School of Economics, CEPR and IZA); Wendelin Schnedler (University of Heidelberg and IZA) 
Abstract:  We investigate a team setting in which workers have different degrees of commitment to the outcome of their work. We show that if there are complementarities in production and if the team manager has some information about team members, interventions that the manager undertakes in order to assure certain efforts may have destructive effects: they can distort the way workers perceive their fellow workers and they may also lead to a reduction of effort by those workers that care most about output. Moreover, interventions may hinder the development of a cooperative organizational culture in which workers trust each other. Thus, our framework provides some first insights into the costs and benefits of interventions in teams. It identifies that team governance is driven by the importance of tasks that cannot be monitored. The more important these tasks, the more likely it is that teams are empowered. 
Keywords:  team work, incentives, informed principal, intrinsic motivation 
JEL:  M54 D86 
Date:  2007–11 
URL:  http://d.repec.org/n?u=RePEc:iza:izadps:dp3143&r=cdm 