A brief note on a further refinement of the Condorcet Jury Theorem for heterogeneous groups

Abstract

I extend Boland's (1989) work on the Condorcet's Jury Theorem (CJT) for heterogeneous groups. I demonstrate that, as long as CJT holds (in that the mean individual competence ≥(1/2)+(1/2 n)), heterogeneous groups are better at making the correct decision than homogeneous groups for any given level of mean competence. I also extend CJT to collective decision rules other than simple majority, and show that CJT holds for groups with supermajority decision rules if the mean individual competence is at least ( π( n+1)/ n) (where π=required majority).