Biases in Group Decision Making

Abstract

Publisher Summary This chapter explains polarization in group decision making by group decision rules, which take into account the rank order of individual preferences over alternatives. Decision rules usually predict the outcome of a group decision on the basis of the individual preferences of the participants by integrating the individual preferences into a collective decision according to the given rule. Most decision rules take into account only the first preferences of the individuals. Some decision rules predict a distribution of group decisions. Others make exact point predictions or specify the range in which the group decision is most likely to fall. Research on shift and polarization has implicitly taken the arithmetic mean of the individual responses as the natural candidate for the group decision. The fact that the actual group decision deviates from the arithmetic mean have been interpreted by psychological effects, such as the effects of group atmosphere, leader characteristics, information exchange effects, and societal values. However, it is easy to verify that most decision rules leads to a shift in relation to the arithmetic mean, when the distribution of the original individual preferences within the group is not completely symmetric.