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A collective choice (or opinion) supported by a majority of individuals is challenged recurrently by a new one in a society. We consider a long-run evolution of collective choice under majority rules by stochastic evolutionary game theory. The Condorcet winner is uniquely a long-run equilibrium for all (super-)majority rules. When the Condorcet winner does not exist, the long-run equilibria under all majority rules belong to the top cycle set. In a multidimensional choice problem where the top cycle set tends to become the whole policy space, a long-run equilibrium belongs to the min–max policy set if the core is non-empty. We show that stochastic evolutionary game theory can mitigate the indeterminacy problem in social choice. [ABSTRACT FROM AUTHOR]

This paper presents a method for unsupervised classification of entities by a group of agents with unknown domains and levels of expertise. In contrast to the existing methods based on majority voting ("wisdom of the crowd") and their extensions by expectation-maximization procedures, the suggested method first determines the levels of the agents' expertise and then weights their opinions by their expertise level. In particular, we assume that agents will have relatively closer classifications in their field of expertise. Therefore, the expert agents are recognized by using a weighted Hamming distance between their classifications, and then the final classification of the group is determined from the agents' classifications by expectation-maximization techniques, with preference to the recognized experts. The algorithm was verified and tested on simulated and real-world datasets and benchmarked against known existing algorithms. We show that such a method reduces incorrect classifications and effectively solves the problem of unsupervised collaborative classification under uncertainty, while outperforming other known methods. [ABSTRACT FROM AUTHOR]

This study establishes sufficient conditions for observing instances of Simpson's (data aggregation) Paradox under rank sum scoring (RSS), as used, e.g., in the Wilcoxon-Mann-Whitney (WMW) rank sum test. The WMW test is a primary nonparametric statistical test in FDA drug product evaluation and other prominent medical settings. Using computational nonparametric statistical methods, we also establish the relative frequency with which paradox-generating Simpson Reversals occur under RSS when an initial data sequence is pooled with its ordinal replicate. For each 2-sample, n-element per sample or 2 x n case of RSS considered, strict Reversals occurred for between 0% and 1.74% of data poolings across the whole sample space, roughly similar to that observed for 2 x 2 x 2 contingency tables and considerably less than that observed for path models. The Reversal rate conditional on observed initial sequence is highly variable. Despite a mode at 0%, this rate exceeds 20% for some initial sequences. Our empirical application identifies clusters of Simpson Reversal susceptibility for publicly-released mobile phone radiofrequency exposure data. Simpson Reversals under RSS are not simply a theoretical concern but can reverse nonparametric or parametric biostatistical results even in vitally important public health settings. Conceptually, Paradox incidence can be viewed as a robustness check on a given WMW statistical test result. When an instance of Paradox occurs, results constituting this instance are found to be data-scale dependent. Given that the rate of Reversal can vary substantially by initial sequence, the practice of calculating this rate conditional on observed initial sequence represents a potentially important robustness check upon a result.

The problem of collective choice is the problem of combining several individual experts' opinions about the order of preference of objects (alternatives) being compared into a single "group" preference. The complexity of collective choice consists in the necessity of processing the ratings of the compared alternatives set by different experts in their own private scales. This article presents the author's original algorithm for processing expert preferences in the problem of collective choice, based on the notion of the total "error" of the experts and measuring their contribution to the collective measure of their consistency. The presentation of the material includes the necessary theoretical part consisting of basic definitions and rules, the statement of the problem and the method itself based on the majority rule, but in the group order of objects. [ABSTRACT FROM AUTHOR]

Copyright of Sociedad y Economia is the property of Universidad del Valle and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, we explore a method of ranking nomination rules as a collective decision‐making procedure. Nomination rules determine which alternatives are eligible for collective decision‐making by aggregating the opinions of nominators, which are expressed positively or negatively. It is possible to compare nomination rules based on their "nominating power" distributions because they can be seen as multiple simple games. Our nomination rules ranking has a two‐step aggregation representation. In the first step, the distribution of nominating power with regard to each issue is aggregated into an indicator based on the sign inversion of the inequality measure of voting power in simple games, as proposed by Laruelle and Valenciano (2004). Subsequently, in the second step, the aggregator sums the indicator on each issue. We add a separability axiom to the set of Laruelle and Valenciano's axioms to characterize our nomination rules ranking that has the two‐step aggregation representation. [ABSTRACT FROM AUTHOR]

This study analyzes a model of collective choice in voting when information is verifiable and pre-voting deliberation is allowed. Each voter has, independently of the others, a positive probability of receiving a private signal about the true state; with complementary probability, the voter is uninformed. Verifiable information means that lying is disallowed during deliberation: informed voters can publicly reveal or hide their signals, while uninformed voters have to disclose their ignorance. We first provide sufficient and necessary conditions under which all voters reveal information fully. Moreover, we derive a counterintuitive result with verifiable information: Voting preceded by deliberation may lead to worse social decisions than a voting process without deliberation. [ABSTRACT FROM AUTHOR]

We analyze a model of binary choice by a committee, when information is hard and pre-voting deliberation is allowed. Each member has, independently of the others, a positive probability of getting a private signal about the true state; with the remaining probability the member is uninformed. Hard information means that lying is disallowed during deliberation—informed members can reveal publicly or hide their signals, while uninformed voters have to disclose their ignorance. We allow non-consequentialist members whose thresholds for switching to the non-status-quo action vary with the number of informative signals. We show that in general, committee members will never reveal information fully during deliberation, even when we rule out partisan types who want the same action in all states. In particular, unanimity rule performs no worse than other rules. [ABSTRACT FROM AUTHOR]

A general setup is considered where quasi-hyperbolic discounting agents differ in assuming heterogeneous bias for the present as well as heterogeneous discounting parameters, consumptions being, moreover, subject to a standard feasibility constraint. A collective utility function is defined as a linear combination of the inter-temporal utilities of the selves of the different agents, the elementary unit being thus the self of a given period of a given agent. Such a framework generating a tension between Pareto-optimality and time consistency for the optimal allocations, a new approach is introduced in order to tackle this issue. This builds from an a priori time-inconsistent collective utility function where the benevolent planner is to be apprehended in terms of a sequence of successive incarnations, any of these incarnations being endowed with its own objective. The associated optimal policy is the equilibrium of a game between the successive incarnations of the planner when the players follow Markovian strategies. This is compared with a more standard approach where restrictions would be imposed on the collective utility function that ensure the time consistency of the optimal decisions. [ABSTRACT FROM AUTHOR]

Effective coordination of group actions underlies the success of group‐living organisms. Making decisions collectively is a crucial step in executing behaviours affecting the whole group. In social insects, decision‐making is typically achieved in a self‐organised manner and incorporates a quorum process, which can improve decision accuracy and be tailored to different conditions. Studies of the nest‐selection process in different social insect species have revealed remarkable consistency in the mode of decision‐making despite marked differences in life history and colony size. However, an often‐overlooked aspect of this decision process is how it might be influenced by diversity in behavioural propensity among colony members. Higher diversity can improve collective processes, but could also represent a cost if certain classes of individual do not contribute to the cooperative activity. Many ant species exhibit caste polymorphism, with different worker castes specialised to different functions. These castes could thus enhance or erode the collective decision process depending on whether they contribute to this process or not. In this study, we explore the process of colony emigration and nest‐site choice in the small carpenter ant Camponotus yamaokai, a species with two distinct worker castes. We show that this species is likely to use a quorum decision process facilitated by navigation with chemical trails. Both major and minor castes contributed to the collective decision and emigration process. However, although major workers comprised 24% of the colony on average, they were 5.5 times less likely than expected to be involved in assessing new nests and 4.6 times less likely than expected to contribute to brood transport. This may represent a previously unrecognised cost to the colony in the emigration process. In addition, we document the first observations of sequential brood transfer during emigration behaviour and speculate upon the function of this behaviour. [ABSTRACT FROM AUTHOR]

Decision making in the system of representative government public administration as a collective choice. The analysis of the political influence of factions in representative bodies of the system of managerial decision-making using index Shapley - Subika and Banzhaf based on the formalism of simple cooperative games, in relation to the Legislative Assembly of the Leningrad region.

This paper is concerned with proposing a new mechanism to re-construct the published composite indicators that are conventionally aggregated in terms of equal weighting scheme, by means of taking all possible preferences among the indicators into account. Regarding to each preference, we apply a sophisticated mathematical transformation to formulate an interval metric. Inspired by the collective choice theory that integrates individual preference into social preference, an interval decision matrix is therefore formulated with preference as column. An interval-valued TOPSIS procedure in conjunction with Shannon entropy objective weights is applied to re-build composite indicators. The proposed methodology is illustrated by modifying the value measure of health systems. The Spearman's rank correlation coefficients between Access, Satisfaction, Efficiency and two versions of value measure are calculated to perform the comparisons and demonstrate the superiority of our methodology. [ABSTRACT FROM AUTHOR]

Weighted committees allow shareholders, party leaders, etc. to wield different numbers of votes or voting weights as they decide between multiple candidates by a given social choice method. We consider committees that apply scoring methods such as plurality, Borda, or antiplurality rule. Many different weights induce the same mapping from committee members’ preferences to winning candidates. The numbers of respective weight equivalence classes and hence of structurally distinct plurality committees, Borda commitees, etc. differ widely. There are 6, 51, and 5 plurality, Borda, and antiplurality committees, respectively, if three players choose between three candidates and up to 163 (229) committees for scoring rules in between plurality and Borda (Borda and antiplurality). A key implication is that plurality, Borda, and antiplurality rule are much less sensitive to weight changes than other scoring rules. We illustrate the geometry of weight equivalence classes, with a map of all Borda classes, and identify minimal integer representations.

This article reviews recent empirical research on collective choice and collaborative problem solving. Much of the collective choice research focuses on hidden profiles. A hidden profile exists when group members individually have information favoring suboptimal choices but the group collectively has information favoring an optimal choice. Groups are notoriously bad at discovering optimal choices when information is distributed to create a hidden profile. Reviewed work identifies informational structures, individual processing biases, and social motivations that inhibit and facilitate the discovery of hidden profiles. The review of collaborative problem-solving research is framed by Larson's concept of synergy. Synergy refers to performance gains that are attributable to collaboration. Recent research has addressed factors that result in groups performing as well as their best member (weak synergy) and better than their best member (strong synergy). Communication dynamics underlying both collective choice and collaborative problem solving are discussed. [ABSTRACT FROM AUTHOR]

Heterospecific aggregations and foraging associations have been observed between different species, from apes to birds to insects. Such associations are hypothesized to result in a mutually beneficial relationship entailing benefits that are not apparent in conspecific groupings. Therefore, the objectives of the present study were to investigate 1) how 3 blowfly species, namely, Calliphora vicina , Calliphora vomitoria , and Lucilia sericata, aggregate according to species, and 2) if developmental benefits are linked to heterospecific aggregation. For objective (1), larvae of 2 species were placed between 2 conspecific aggregates, each with a different species (i.e. a binary choice test). After 20 h, the positions of all larvae were determined. On average, 98% of the maggots added later settled together on one of the 2 pre-existing aggregations, demonstrating a collective choice. The aggregation spot with C. vicina was preferred against others, indicating different attractiveness of different species. To relate this behavior to its benefits (objective ii), C. vicina and L. sericata larvae were raised from first instar to adult in con- and heterospecific conditions, and their development time, mortality rates, and morphometrics were measured. Thereby, mutual and asymmetric consequences were observed: specifically, there were significant increases in size and survival for L. sericata and faster development for C. vicina in heterospecific groups. These results indicate that the predilection for heterospecific association leads to mutual developmental benefits. This heterospecific aggregation behavior may be a resource-management strategy of blowflies to face carrion-based selection pressure. [ABSTRACT FROM AUTHOR]

Societies must make collective decisions even when citizens disagree, and they use many different political processes to do so. But how do people choose one way to make a group decision over another? We propose that the human mind contains an intuitive political theory about how to make collective decisions, analogous to people's intuitive theories about language, physics, number, minds, and morality. We outline a simple method for studying people's intuitive political theory using scenarios about group decisions, and we begin to apply this approach in three experiments. Participants read scenarios in which individuals in a group have conflicting information (Experiment 1), conflicting interests (Experiment 2), and conflicting interests between a majority and a vulnerable minority who have more at stake (Experiment 3). Participants judged whether the group should decide by voting, consensus, leadership, or chance. Overall, we find that participants prefer majority‐rule voting over consensus, leadership, and chance when a group has conflicting interests or information. However, participants' support for voting is considerably diminished when the group includes a vulnerable minority. Hence, participants showed an intuitive understanding of Madison's concerns about tyranny of the majority. [ABSTRACT FROM AUTHOR]

Copyright of Revue d'Économie Régionale & urbaine is the property of Librairie Armand Colin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article provides a response to the contributors of this symposium. Notably, I respond to challenges pertaining to whether my account can: accommodate collective goods and collective choice and the complexities pertaining to intergenerational justice; be reconciled with the insights of relational egalitarianism and non-ideal theory; meet the requirement that it provides political action guidance instead of being practically irrelevant; be grounded in Rawls' considerations about luck and justice; avoid implausible implications regarding 'concern monsters' and offensive preferences. [ABSTRACT FROM AUTHOR]