Template-type: ReDIF-Paper 1.0
Author-Name: Franz Dietrich
Author-Workplace-Name:Group on Philosophy, Probability and Modelling, University of Konstanz, Germany 
Author-Name: Christian List
Author-Email:christian.list@nuf.ox.ac.uk 
Author-Workplace-Name: Nuffield College, University of Oxford, Oxford, UK
Title: A Model of Jury Decisions Where All Jurors Have the Same Evidence
Abstract:
 In 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.
Classification-JEL:D71, D72
Keywords:  Condorcet jury theorem, conditional independence, interpretation of evidence, Bayesian trees
Length:12 pages
Creation-Date: 2002-09-24
Number:2002-W23
File-URL:http://www.nuff.ox.ac.uk/economics/papers/2002/w23/CJTDietrichList.pdf
File-Format: application/pdf
Handle: RePEc:nuf:econwp:0223