On the Composition of Committees ∗

This paper is concerned with the role of committees in collective decisionmaking processes in a world where agents must be motivated to collect information. Committees improve the quality of decision-making by providing information and by coordinating the collection of information. We address two types of questions. First, how does the composition of a committee affect final decisions? Second, what is the optimal composition of a committee from the decision maker’s point of view? As to the latter question, we show that the cost of information collection plays an important role. If this cost is low, then the preferences of the committee members should be aligned to those of the decision maker. Members with similar preferences as the decision maker collect the proper pieces of information. Moreover, manipulation of information does not occur if the preferences of the decision maker and the members are consonant. If the cost of searching is high, then the committee should be composed of members with polarized preferences. Outliers have a strong incentive to search for information.