Group decisions with multiple criteria

We consider a decision problem where a group of individuals evaluates multiattribute alternatives. We explore the minimal required agreements that are sufficient to specify the group utility function. A surprising result is that, under some conditions, a bilateral agreement among pairs of individuals on a single attribute is sufficient to derive the multi-attribute group utility. The bilateral agreement between a pair of individuals could be on the weight of an attribute, on an attribute evaluation function, or on willingness to pay. We focus on the case in which each individual's utility function is additive. We show that the group utility can be represented as the weighted sum of group attribute weights and, more remarkably, of attribute evaluation functions. These group attribute evaluation functions are in turn weighted sums of individual attribute evaluation functions.