Testing the Framework of Other-Regarding Preferences

We assess the empirical validity of the overall theoretical framework of other-regarding preferences by focusing on those preference axioms that are common to all the prominent theories of outcome-based other-regarding preferences. This common set of preference axioms leads to a testable implication: the strict preference ranking of self over a finite number of alternatives lying on any straight line in the space of material payoffs to self and other will be single-peaked. The extent of single-peakedness varies from a high of 79% to a low of 54% across our treatments that are based on dictator and trust games. Positively and/or negatively other-regarding subjects are significantly less likely to report single-peaked rankings relative to self-regarding subjects. We delineate the potential reasons for violations of single-peakedness and discuss the implications of our findings for theoretical modeling of other-regarding preferences.Other-regarding preferences, social preferences, decision making under risk, single-peaked preferences, experiments

Testing the Analytical Framework of Other-Regarding Preferences

This paper aims to assess the empirical validity of the overall theoretical framework of other-regarding preferences. We focus on those preference axioms that are common to all the prominent theories of outcome-based other-regarding preferences. This common set of preference axioms leads to a testable implication: the strict preference ranking of self over a _nite number of alternatives lying on any straight line in the space of material payoffs to self and other will be single-peaked. We elicit the strict preference rankings of experimental subjects in variants of dictator and trust games using a mechanism that induces truthful revelation under quite weak assumptions. The data allow us to document the extent of single-peakedness and identify who violates single-peakedness. Potential reasons for violations of single-peakedness are delineated and the implications of our findings for theoretical modeling of other-regarding preferences are discussed.Other-regarding preferences, expected utility theory, single-peaked preferences, Experiments

An Influence of Voters' Preferences on the Stable Parliamentary Seat Share

In this paper, we show that the dynamics of a parliament seat share using an adoptive process modeled by urn scheme. In particular, we clarify the condition under which one dominant party or co-existence arises, when voters recognize the political effectiveness as important. One of the important factors for voters to decide their voting is how a political party's proposal is close to their ideal, which reflects their religion, social class, age and so on. There exists another important factor to choose a party. In the literature it is often supposed that the winning party has the power to implement any proposal with probability 1. However, voters have room to consider the likelihood that a party will implement its proposal, i.e., the political effectiveness. Some of voters may be more in favor of the policy that was announced by the defeated party; others, on the contrary, may be in favor of the winning party's proposal. The actions taken by the government are influenced by voters. The influence of voters in favor of a proposal will become bigger if the proportion of seats obtained by the corresponding party. Clearly a party winning 51% of the seats will have more difficulty to carry out its proposal than one winning 80% of the seats. As show in Duverger(1967), voters for small parties will see that their vote is being `wasted' and they will switch to supporting a major party. We consider the case where voters pay attention to two points to choose a party; the closeness between a party's ideology and own ideal, and the political effectiveness. Here, we consider the simple society where there are two parties, say, X and Y, and three type voters, say, x, y, and z. Voter x receives positive benefit from X and negative one from Y. She always votes for party X tough X has any low seat share. Conversely, voter y obtains negative benefit from X and positive one from Y. He votes for party Y irrespective of the seat share of Y. Voter z gets the same benefits from both parties. Party X and Y are indifferent for voter z. Voter z votes for a party with higher seat share. Voter x and y count the closeness to a party strongly and they ignore the political effectiveness. Voter x has the low critical seat share to vote for party X and voter y has the high critical seat share to vote for X. Voter z pays attention to the political effectiveness. He has the moderate critical seat share to vote for party X. We regard a voter's critical seat share as a voter's preference. For purposes of comparison we consider two shapes of distribution of voters' preferences, bimodal and single-peaked. If voters' preferences are distributed as bimodal, each party has strong supporters who always vote for the support party and the proportion of voters who care the political effectiveness as important is small. As each party has strong supports potentially even if it leaves what initial state, in progress of time, two seat shares become equivalent, i.e., the long term co-existence is realized in the equilibrium. Conversely, if voters' preferences are distributed as single-peaked, most voters are interested in the political effectiveness. Then, a party with higher seat share is more attractive for voters and it gains an even higher seat share. After all, a party with a high initial seat share comes into power, i.e., the lock-in into one of political party is realized. The dynamics treated in this paper is the generalized urn process discussed in Hill et al. (1980), Arthur et al. (1983), and Dosi et al. (1994). As Dosi et al. (1994) mentioned, by specifying the function which characterizes an agent's behavior, it is possible to analyze the stochastic evolution of the share. We define the voters' behavioral patterns and demonstrate how the global forces ruling the dynamics of whole populations can be derived from the individual behavior of votersPolitical effectiveness, Voter's preference, Urn process

Computational Aspects of Nearly Single-Peaked Electorates

Manipulation, bribery, and control are well-studied ways of changing the outcome of an election. Many voting rules are, in the general case, computationally resistant to some of these manipulative actions. However when restricted to single-peaked electorates, these rules suddenly become easy to manipulate. Recently, Faliszewski, Hemaspaandra, and Hemaspaandra studied the computational complexity of strategic behavior in nearly single-peaked electorates. These are electorates that are not single-peaked but close to it according to some distance measure. In this paper we introduce several new distance measures regarding single-peakedness. We prove that determining whether a given profile is nearly single-peaked is NP-complete in many cases. For one case we present a polynomial-time algorithm. In case the single-peaked axis is given, we show that determining the distance is always possible in polynomial time. Furthermore, we explore the relations between the new notions introduced in this paper and existing notions from the literature.Comment: Published in the Journal of Artificial Intelligence Research (JAIR). A short version of this paper appeared in the proceedings of the Twenty-Seventh AAAI Conference on Artificial Intelligence (AAAI 2013). An even earlier version appeared in the proceedings of the Fourth International Workshop on Computational Social Choice 2012 (COMSOC 2012

An Empirical Comparison of Three Inference Methods

In this paper, an empirical evaluation of three inference methods for uncertain reasoning is presented in the context of Pathfinder, a large expert system for the diagnosis of lymph-node pathology. The inference procedures evaluated are (1) Bayes' theorem, assuming evidence is conditionally independent given each hypothesis; (2) odds-likelihood updating, assuming evidence is conditionally independent given each hypothesis and given the negation of each hypothesis; and (3) a inference method related to the Dempster-Shafer theory of belief. Both expert-rating and decision-theoretic metrics are used to compare the diagnostic accuracy of the inference methods.Comment: Appears in Proceedings of the Fourth Conference on Uncertainty in Artificial Intelligence (UAI1988

Recognising Multidimensional Euclidean Preferences

Euclidean preferences are a widely studied preference model, in which decision makers and alternatives are embedded in d-dimensional Euclidean space. Decision makers prefer those alternatives closer to them. This model, also known as multidimensional unfolding, has applications in economics, psychometrics, marketing, and many other fields. We study the problem of deciding whether a given preference profile is d-Euclidean. For the one-dimensional case, polynomial-time algorithms are known. We show that, in contrast, for every other fixed dimension d > 1, the recognition problem is equivalent to the existential theory of the reals (ETR), and so in particular NP-hard. We further show that some Euclidean preference profiles require exponentially many bits in order to specify any Euclidean embedding, and prove that the domain of d-Euclidean preferences does not admit a finite forbidden minor characterisation for any d > 1. We also study dichotomous preferencesand the behaviour of other metrics, and survey a variety of related work.Comment: 17 page

Secure Implementation Experiments: Do Strategy-proof Mechanisms Really Work?

Strategy-proofness, requiring that truth-telling is a dominant strategy, is a standard concept used in social choice theory. Saijo et al. (2003) argue that this concept has serious drawbacks. In particular, announcing one's true preference may not be a unique dominant strategy, and almost all strategy-proof mechanisms have a continuum of Nash equilibria. For only a subset of strategy-proof mechanisms do the set of Nash equilibria and the set of dominant strategy equilibria coincide. For example, this double coincidence occurs in the Groves mechanism when preferences are single-peaked. We report experiments using two strategy-proof mechanisms where one of them has a large number of Nash equilibria, but the other has a unique Nash equilibrium. We found clear differences in the rate of dominant strategy play between the two.