The importance of expertise in group decisions

Abstract

Prior to a collective binary choice, members of a group receive binary signals correlated with the better option. A larger group size may produce less accurate decisions, but expertise is everywhere beneficial. If a group accounts for correlation in signals, a relatively expert member puts an upper bound on the probability of a false belief. The bound holds for any group size and signal distribution. Furthermore, a population investing in expertise is better off cultivating a small mass of elites than adopting an egalitarian policy of education.