ABSTRACT
This chapter focuses on received wisdom concerning group decision by working together on a problem, arriving at a better solution than to ponder the problem alone. First, all members of the group provided an independent individual sales estimate which were then collated to provide a 'collective mean' judgment for the group. Second, one of four different group-decision techniques was imposed on the group: dictator, consensus, dialectic or Delphi. It argues that this two-stage model involves the conceptually distinct processes of revision and weighting, which can both operate to transform the distribution of individual judgments into a consensus group judgment. Probability training highlighted many of the biases and fallacies that we have discussed throughout this book, such as base-rate neglect, over-confidence and confirmation bias. Probability training proved more effective than scenario training, and both were superior to no training. Working in a team that could communicate resulted in more accurate forecasts than working alone or in non-communicating groups.
