Existing proofs of Condorcet's Jury Theorem formulate only sufficient conditions for its validity. This paper provides necessary and sufficient conditions for Condorcet's Jury Theorem. The framework of the analysis is the case of heterogeneous decisional competence, but the independence...

Consider a committee of experts dealing with dichotomous choice problem, where the correctness probabilities are all greater than [InlineMediaObject not available: see fulltext.] We prove that, if a random subcommittee of odd size m is selected randomly, and entrusted to make a decision by...

There is a large body of research studying the conditions under which majority decisions are best. In particular, in many circumstances, the probability of a group to decide correctly is higher than that of a random subgroup. Moreover, the latter probability increases as the subgroup size grows....