INFORMATION, INDIVIDUAL ERRORS, AND COLLECTIVE PERFORMANCE - EMPIRICAL-EVIDENCE ON THE CONDORCET-JURY-THEOREM

The Condorcet Jury Theorem implies that the collective performance of a group, in arriving at a ''correct'' judgment on the basis of majorit y or plurality rule, will be superior to the average performance of in dividual members of the group, if certain apparently plausible conditi ons hold. Variants of the Jury Theorem are reviewed, particularly incl uding the politically relevant variant that allows for conflicting int erests within the group. we then examine two kinds of empirical data. First, we compare individual and collective performance in a large num ber of multiple-choice tests, and we find that collective performance invariably and substantially exceeds average individual performance. S econd, we analyze American National Election Study data to create dich otomous-choice tests concerning positions of candidates on a variety o f political issues; Condorcet-like effects are again evident. Finally, continuing to use NES data, we construct, on each political issue, a simulated referendum (direct voting on the issue) and election (indire ct voting on the issue by voting for candidates on the basis of their perceived positions on the issue), and we compare the two results. Des pite high rates of individual error, electoral error is quite small, a nd collective performance is fairly high, providing evidence of Condor cet-like effects in situations of conflicting preferences.