“Information Aggregation with Costly Reporting”

Martin J. Osborne, University of Toronto

Jeffrey S. Rosenthal, University of Toronto

Colin Stewart, University of Toronto

A group of individuals with common interests has to choose a binary option whose desirability depends on an unknown binary state of the world. The individuals independently and privately observe a signal of the state. Each individual chooses whether to reveal her signal, at a cost.  We show that if for all revelation choices of the individuals the option chosen by the group is optimal given the signals revealed and the set of individuals who do not reveal signals, then in a large group few signals are revealed, and these signals are extreme.  The correct decision is taken with high probability in one state but with probability bounded away from one in the other. No anonymous decision-making mechanism without transfers does better. However, the first-best average payoff can be attained using transfers among agents, and approximately attained with a non-anonymous mechanism without transfers.