Aggregation of expert opinions

Conflicts of interest arise between a decision maker and agents who have information pertinent to the problem because of differences in their preferences over outcomes. We investigate how the decision maker can extract the information by distorting the decisions that will be taken. We show that only slight distortions will be necessary when agents' signals are sufficiently accurate or when the number of informed agents becomes large. We argue that the particular mechanisms analyzed are substantially less demanding informationally than those typically employed in implementation and virtual implementation. Further, the mechanisms are immune to manipulation by small groups of agents.