T-Space Collection:http://hdl.handle.net/1807/174062014-04-04T20:09:00Z2014-04-04T20:09:00ZChoice deferral and ambiguity aversionIgor Kopylov; Department of Economics and Institute for Mathematical Behavioral Sciences, University of California, Irvinehttp://hdl.handle.net/1807/174102010-12-10T21:23:30Z2009-06-09T00:00:00ZTitle: Choice deferral and ambiguity aversion
Authors: Igor Kopylov; Department of Economics and Institute for Mathematical Behavioral Sciences, University of California, Irvine
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When confronted with uncertain prospects, people often exhibit both choice deferral and Ellsberg-type ambiguity aversion. This paper obtains a joint representation
for these behavioral phenomena. The decision maker as portrayed by my model
is willing to choose an uncertain prospect f over g rather than to defer this choice
if and only if the expected utility of f is greater that or equal to the expected utility of g for every probability measure in a convex and closed set Delta. This set is interpreted as a collection of the decision maker's possible future beliefs. When choices cannot be deferred, the decision maker evaluates every uncertain prospect via an epsilon-mixture of the least favorable element in the set Delta and her current probabilistic belief p in Delta. All components of my model are derived from observable preferences in an essentially unique way.2009-06-09T00:00:00ZStrategy-proofness and single-crossingAlejandro Saporiti; School of Social Sciences, University of Manchesterhttp://hdl.handle.net/1807/174092010-12-10T21:23:28Z2009-06-09T00:00:00ZTitle: Strategy-proofness and single-crossing
Authors: Alejandro Saporiti; School of Social Sciences, University of Manchester
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This paper analyzes strategy-proof collective choice rules when individuals have single-crossing preferences on a finite and ordered set of social alternatives. It shows that a social choice rule is anonymous, unanimous, and strategy-proof on a maximal single-crossing domain if and only if it is an extended median rule with n-1 fixed ballots distributed over the individuals' most preferred alternatives. As a by-product, the paper also proves that strategy-proofness implies the tops-only property. It also offers a strategic foundation for the so-called "single-crossing version" of the Median Voter Theorem, by showing that the median ideal point can be implemented in dominant strategies by a direct mechanism in which every individual reveals his true preferences.2009-06-09T00:00:00ZAsymptotic ordinal inefficiency of random serial dictatorshipMihai Manea; Department of Economics, Harvard Universityhttp://hdl.handle.net/1807/174082010-12-10T21:23:26Z2009-06-09T00:00:00ZTitle: Asymptotic ordinal inefficiency of random serial dictatorship
Authors: Mihai Manea; Department of Economics, Harvard University
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We establish that the fraction of preference profiles for which the random serial dictatorship allocation is ordinally efficient vanishes for allocation problems with many object types. We consider also a probabilistic setting where in expectation agents have moderately similar preferences reflecting varying popularity across objects. In this setting we show that the probability that the random serial dictatorship mechanism is ordinally efficient converges to zero as the number of object types becomes large. We provide results with similarly negative content for allocation problems with many objects of each type. One corollary is that ordinal efficiency is a strict refinement of ex-post efficiency at most preference profiles.2009-06-09T00:00:00ZA resurrection of the Condorcet Jury TheoremYukio Koriyama; Dértement d'Éonomie, Éole Polytechnique, PalaiseauBalazs Szentes; Department of Economics, University College Londonhttp://hdl.handle.net/1807/174072010-12-10T21:23:22Z2009-06-09T00:00:00ZTitle: A resurrection of the Condorcet Jury Theorem
Authors: Yukio Koriyama; Dértement d'Éonomie, Éole Polytechnique, Palaiseau; Balazs Szentes; Department of Economics, University College London
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This paper analyzes the optimal size of a deliberating committee where (i) there is no conflict of interest among individuals and (ii) information acquisition is costly. The committee members simultaneously decide whether to acquire information, and then make the ex-post efficient decision. The optimal committee size, k*, is shown to be bounded. The main result of this paper is that any arbitrarily large committee aggregates the decentralized information more efficiently than the committee of size k*-2. This result implies that oversized committees generate only small inefficiencies.2009-06-09T00:00:00Z