On the learnability of majority rule

We establish how large a sample of past decisions is required to predict future decisions of a committee with few members. The committee uses majority rule to choose between pairs of alternatives. Each member's vote is derived from a linear ordering over all the alternatives. We prove that there are cases in which an observer cannot predict precisely any decision of a committee based on its past decisions. Nonetheless, approximate prediction is possible after observing relatively few random past decisions.     

Speed and quality of collective decision making: Imperfect information processing

This paper studies efficient programmed hierarchies as introduced by Radner [The organization of decentralized information processing, Econometrica 61(5) (1993) 1109-1146] in which agents cannot process information perfectly. A group of P identical managers has to make a choice between n alternatives. In order to learn which is the best option, the alternatives have to be compared. The evaluation of an alternative takes time and managers are only able to identify the better one of two alternatives with a positive probability. The skip-level reporting tree proposed by Radner is found to be efficient in terms of the dimensions decision cost, decision delay, and decision quality.     

How individuals choose health insurance: An experimental analysis

An individual choosing a health insurance policy faces a complex decision environment where a large set of alternatives differ on a variety of dimensions. There is uncertainty and the choice is repeated at least once a year. We study decisions and decision strategies in a laboratory experiment where we create a controlled environment that closely mirrors this setting. We use an electronic information board that allows to carefully monitor the individual's decision strategy. The number of alternatives, switching costs, and the speed at which health deteriorates are varied across treatments. We find that most subjects' search is based more on attributes than on policies. Moreover, we find that an increase in the number of alternatives increases decision-making time; makes subjects consider a lower fraction of the available information; makes it more likely that subjects will switch; and decreases the quality of their decisions. The introduction of positive costs of switching makes people switch less often but improves the quality of their decisions. Finally, if health deteriorates only gradually, individuals tend to stick to their current policy too long.     

科学、价值与判断在环境影响评估架构中之整合

公共政策研拟，尤其是环境影响评估，不仅牵涉技术性科学层面，同时涵盖社会性价值评估与政策性决策判断。旨在探讨如何将科学、价值与判断等因素合理融合于环境影响评估作业过程中，并据此研拟一环境影响评估架构，作为中国台湾地区环保部门开发案审核依据之参考。本文所研拟之环境影响评估架构的理论基础包括社会选择理论、社会判断理论及多属性评估方法。通过社会选择理论分析环境政策制定的机制；通过社会判断理论解释科学与价值如何整合于政策制定及其可行性中；而通过多属性评估方法建立开发案评选的集体决策技术。以山坡地开发为例说明此架构在实践中的应用。     

Group decision-making in the shadow of disagreement

A model of group decision-making is studied, in which one of two alternatives must be chosen. While agents differ in their preferences over alternatives, everybody prefers agreement to disagreement. Our model is distinguished by three features: private information regarding valuations, differing intensities in preferences, and the option to declare neutrality to avoid disagreement. There is always an equilibrium in which the majority is more aggressive in pushing its alternative, thus enforcing their will via both numbers and voice. However, under general conditions an aggressive minority equilibrium inevitably makes an appearance, provided that the group is large enough. Such equilibria invariably display a “tyranny of the minority”: the increased aggression of the minority always outweighs their smaller number, leading to the minority outcome being implemented with larger probability than the majority alternative. We fully characterize the asymptotic behavior of this model as group size becomes large, and show that all equilibria must converge to one of three possible limit outcomes.     

A testable model of consumption with externalities

This paper presents a nonparametric model of interdependent preferences, where an individual's consumption may act as an externality on the preferences of other consumers. We assume that individual price consumption data is observed for all consumers. It is known that the general consumption model with externalities imposes few restrictions on the observed data, where the consistency requirement is Nash rationalizability. We motivate potential games as an important sub class of games where the family of concave potential games is refutable and imposes stronger restrictions on observed data. We use this framework to extend the analysis of Brown and Matzkin [D. Brown, R. Matzkin, Testable restrictions on the equilibrium manifold, Econometrica 64 (1996) 1249-1262] on refutable pure exchange economies to pure exchange economies with externalities. Finally, we discuss an application of this model to inter-household consumption data.     

Strategic resource dependence

We consider a situation where an exhaustible-resource seller faces demand from a buyer who has a substitute but there is a time-to-build delay for the substitute. We find that in this simple framework the basic implications of the Hotelling model (1931) are reversed: over time the stock declines but supplies increase up to the point where the buyer decides to switch. Under such a threat of demand change, the supply does not reflect the current resource scarcity but it compensates the buyer for delaying the transition to the substitute. The analysis suggests a perspective on costs of oil dependence.     

Moral hazard,insurance claims,and repeated insurance contracts

Abstract The paper develops a simple model of repeated automobile insurance contracts, providing a framework for analyzing changes in aggregate insurance data in periods of changes that affect driver incentives. Experience rating of premiums gives drivers an incentive to exert effort to avoid accidents (ex ante moral hazard), and an incentive to hide accidents (ex post moral hazard). The empirical analysis, using data from the competitive insurance markets in Ontario and Alberta over a period of major legislative changes in Ontario, suggests that much of the recent decline in accidents in Ontario was due to an increased incentive to hide accidents.     

Learnability and rationality of choice

In this paper we study the learnability of the class of rationalizable choice functions using the basic concept of PAC-learnability from statistical learning theory. We prove that the class of rationalizable choice functions on N alternatives is learnable from O(N) examples and is optimal in terms of PAC-learnability among classes which are invariant under permutations of the elements.     

FINANCIAL ACCOUNTS AND BALANCE SHEETS: ISSUES FOR THE REVISION OF SNA

This paper is an abridged version of a report with the same title originally written for the United Nations Statistical Office, as a part of the ongoing review of the System of National Accounts. Its purpose is to identify the issues in the financial statistics area that need to be considered in the course of the review. Particular attention is paid to problems of harmonization of SNA with related standards of the International Monetary Fund. The 1968 SNA provided a place in the framework for financial accounts and balance sheets, but did not develop them in any detail. In the 19 years since the revised SNA was published, policy and analytic interest in financial questions has greatly increased, and much work has been done on conceptual development and statistical compilation of financial statistics, both within and outside of the SNA framework. It is now apparent that some of the early decisions taken when financial considerations were not the focus of attention need reconsideration, some of the makeshift solutions that have grown up over time are no longer adequate, and some issues that have not been dealt with at all need to be addressed. This paper is not intended to propose solutions, but rather to reflect questions that have been raised, and to present alternatives that have been proposed.     

Return migration, wage differentials, and the optimal migration duration

In simple static models, migration increases with the wage differential between host- and home-country. In a dynamic framework, and if migrations are temporary, the size of the migrant population in the host country depends also on the migration duration. This paper analyses optimal migration durations in a model which rationalises the decision of the migrant to return to his home country, despite persistently higher wages in the host country. The analysis shows that, if migrations are temporary, the optimal migration duration may decrease if the wage differential grows larger. Using micro data for Germany, the second part of the paper provides empirical evidence which is compatible with this hypothesis.     

Erratum to “Negotiation and take it or leave it in common agency”: [Journal of Economic Theory 111 (2003) 88-109]

The no-externalities condition provided in the text is not sufficient for Theorems 3 and 4 when effort is not fully contractable. In the case where the principals cannot contract at all on agent's effort, the condition in the text requires that for any set of alternatives offered by the principal there is one that is at least as good as all other alternatives in the set for the agent no matter what the other principal does, no matter what effort the agent takes, and no matter what the agent's type. In fact, a stronger condition is required. For any set of alternatives offered by a principal, each of the choices within this set that is at least as good for the agent as any other choice within the set must remain so no matter what actions the other principals take, no matter what effort the agent takes, and no matter what the agent's type.     

An additively separable representation in the Savage framework

This paper proposes necessary and sufficient conditions for an additively separable representation of preferences in the Savage framework (where the objects of choice are acts: measurable functions from an infinite set of states to a potentially finite set of consequences). A preference relation over acts is represented by the integral over the subset of the product of the state space and the consequence space which corresponds to the act, where this integral is calculated with respect to an evaluation measure on this space. The result requires neither Savage's P3 (monotonicity) nor his P4 (weak comparative probability). Nevertheless, the representation it provides is as useful as Savage's for many economic applications.     

Weak Independence and Social Semi‐Orders

This paper provides variants of Arrow's impossibility theorem, which states that there exists no non‐dictatorial aggregation rule satisfying weak Pareto, independence of irrelevant alternatives and collective rationality. In this paper, independence of irrelevant alternatives and collective rationality are simultaneously relaxed. Weak independence is imposed instead of independence of irrelevant alternatives. Social preferences are assumed to satisfy the semi‐order properties of semi‐transitivity and the interval‐order property. We prove that there exists a vetoer when the number of alternatives is greater than or equal to six.     

Condorcet Jury Theorem: An example in which informative voting is rational but leads to inefficient information aggregation

Recent research on the Condorcet Jury Theorem has proven that informative voting (that is, voting according to one’s signal) is not necessarily rational. With two alternatives, rational voting typically leads to the election of the correct alternative, in spite of the fact that not all voters vote informatively. We prove that with three alternatives, there are cases in which informative voting is rational and yet leads to the election of a wrong alternative.     

Participative multi-criteria analysis for the evaluation of water governance alternatives. A case in the Costa del Sol (Málaga)

This paper presents the results of a participatory multi-criteria evaluation of urban water supply alternatives in Costa del Sol Occidental in Málaga (Spain). Multi-criteria and social research techniques were combined, relying on social actors' involvement throughout the research work. The paper documents that participatory processes allowed to unveil framings, perspectives, values and interests, as well as understanding of the social and institutional context in which the waters are governed. The deployment of this methodological approach has in this case provided an extended diagnosis which was the starting point to explore non a priori foreseen management alternatives by the researchers. The methodological approach proved useful for problem structuring in a collective, flexible and iterative way, unveiling existing water management conflicts and their motivations, and improving the quality and effectiveness of the information exchange and the reflection process, among social actors, even if the whole process developed in a research setting rather than in a policy for real one. Participatory multi-criteria evaluation could in this case, contribute to identify policy options that could be better defended before all the social actors, including the general public, thus attempting to achieve shared ground. The paper suggests some methodological considerations for applying participatory multi-criteria evaluation based on the outcomes of the case study application.     

The impact and spin-off of participatory backcasting: From vision to niche

This paper reports on a study that has systematically investigated the follow-up and spin-off of participatory backcasting experiments in the Netherlands five to ten years after completion. A methodological framework for participatory backcasting is presented, after which a conceptual framework is developed to describe and evaluate the impact of backcasting experiments. Three cases are analysed: (1) Novel Protein Foods and meat alternatives; (2) Sustainable Household Nutrition; and (3) Multiple Sustainable Land-use in rural areas. The cases show that participatory backcasting can lead to substantial follow-up and spin-off, but that is not always the case. Substantial follow-up and spin-off after five to ten years is predominantly found at the level of niches, and can be seen as potential seeds for future system innovations. The emergence of follow-up and spin-off comes along with the diffusion of the visions generated in the backcasting experiment. The visions provide orientation (where to go) and guidance (what to do). Visions also show both stability and flexibility. Factors that influence the extent of impact and spin-off of backcasting are identified, with a focus on stakeholders, learning and visions. Finally, relevance for system innovation theory, governance and policy as well as research recommendations are briefly discussed.     

Terrorist backlash, terrorism mitigation, and policy delegation

This paper presents a three-stage proactive game involving terrorists, elected policymakers, and voters. In each of two targeted countries, a representative voter chooses an elected policymaker, charged with deciding proactive countermeasures to ameliorate a transnational terrorist threat. Two primary considerations drive the voters' strategic choice: free riding on the other countries' countermeasures and limiting a reprisal terrorist attack. The resulting low proactive countermeasures benefit the terrorists, whose attacks successfully exploit voters' strategic actions. This finding stems from a delegation problem where leadership by voters has a detrimental consequence on the well-being of targeted countries. Domestic politics add another layer of concern when addressing a common terrorist threat.     

Strategy-Proof Probabilistic Mechanisms in Economies with Pure Public Goods

Public good economies where agents are endowed with strictly convex continuous single-peaked preferences on a convex subset of Euclidean space are considered. Such an economy arises for instance in the classical problem of allocating a given budget to finance the provision of several public goods where the agents have monotonically increasing strictly convex continuous preferences. A probabilistic mechanism assigns a probability distribution over the feasible alternatives to any profile of reported preferences. The main result of the paper establishes that any strategy-proof (in the sense of A. Gibbard, Econometrica45 (1977), 665-681) and unanimous mechanism must be a random dictatorship. Journal of Economic Literature Classification Numbers: D70, D71, H40, C60.     

Non-marketed options, non-existence of equilibria, and non-linear prices

This paper presents a surprising example that shows that the lattice theoretic properties in Mas-Colell's (1986) seminal work are relevant to the existence of equilibrium even when the commodity space is finite dimensional.The example is a two-period securities model with a three-dimensional portfolio space and two traders. The paper identifies a non-marketed call option that fails to have a minimum cost super-replicating portfolio. Using this option, we construct an economy that satisfies all of Mas-Colell's assumptions, except that the three-dimensional commodity space is not a vector lattice. In this economy, there is no Walrasian equilibrium and the second theorem of welfare economics fails.Our example has important finite- as well as infinite-dimensional implications. It is also an example of a “well behaved” economy in which optimal allocations that are not supported by linear Walrasian prices are decentralized by the non-linear prices studied in Aliprantis-Tourky-Yannelis (2001).