Strategic manipulation in group decisions with pairwise comparisons: A game theoretical perspective

We discuss the issue of strategic manipulation in group decision-making via pairwise comparisons. Pairwise comparisons play a pivotal role in the analytic hierarchy process (AHP). Although there is a large amount of literature on its application to group decisions, very little attention has been paid to the strategic issue: a group decision can be biased by strategically dishonest individuals. We aim to draw attention to the problem and provide a formal perspective to deal with it. We consider a scenario of group decision-making where the inputs are the individuals’ pairwise preferences and the outcome is in their interest. We formulate this situation as a strategic game where the individuals decide how to submit their pairwise preferences. Theoretical results show that truthful reporting can be a dominant strategy only in very limited situations, and moreover it is often weakly dominated.