A Model of Jury Decisions Where All Jurors Have The Same Evidence
AbstractIn the classical Condorcet jury model, different jurors votes are independent random variables, where each juror has the same probability p>1/2 of voting for the correct alternative. The probability that the correct alternative will win under majority voting converges to 1 as the number of jurors increases. Hence the probability of an incorrect majority vote can be made arbitrarily small, a result that may seem unrealistic. A more realistic model is obtained by relaxing the assumption of independence and relating the vote of every juror to the same body of evidence. In terms of Bayesian trees, the votes are direct descendants not of the true state of the world (guilty or not guilty), but of the body of evidence, which in turn is a direct descendant of the true state of the world. This permits the possibility of a misleading body of evidence. Our main theorem shows that the probability that the correct alternative will win under majority voting converges to the probability that the body of evidence is not misleading, which may be strictly less than 1.
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Bibliographic InfoPaper provided by University of Oxford, Department of Economics in its series Economics Series Working Papers with number 2002-W23.
Date of creation: 01 Sep 2002
Date of revision:
Condorcet jury theorem; conditional independence; interpretation of evidence; Bayesian trees;
Other versions of this item:
- Franz Dietrich & Christian List, 2002. "A Model of Jury Decisions Where All Jurors Have the Same Evidence," Economics Papers 2002-W23, Economics Group, Nuffield College, University of Oxford.
- D71 - Microeconomics - - Analysis of Collective Decision-Making - - - Social Choice; Clubs; Committees; Associations
- D72 - Microeconomics - - Analysis of Collective Decision-Making - - - Political Processes: Rent-seeking, Lobbying, Elections, Legislatures, and Voting Behavior
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- Daniel Berend & Jacob Paroush, 1998. "When is Condorcet's Jury Theorem valid?," Social Choice and Welfare, Springer, vol. 15(4), pages 481-488.
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"Epistemic Democracy with Defensible Premises,"
066, Maastricht University, Maastricht Research School of Economics of Technology and Organization (METEOR).
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- Wojciech Charemza & Daniel Ladley, 2012. "MPC Voting, Forecasting and Inflation," Discussion Papers in Economics 12/23, Department of Economics, University of Leicester, revised Jan 2013.
- Bezalel Peleg & Shmuel Zamir, 2009. "On Bayesian-Nash Equilibria Satisfying the Condorcet Jury Theorem: The Dependent Case," Discussion Paper Series dp527, The Center for the Study of Rationality, Hebrew University, Jerusalem.
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