A consistency and consensus model for group decision support based on the outranking approach

When a group of decision-makers faces the problem of ranking a set of decision alternatives, it is usually necessary to reach a consensus among the group members on ranking alternatives. However, before that, we should minimize inconsistencies between the fuzzy outranking relation and the final ranking at the individual and group levels in the outranking approach of multiple criteria decision analysis. This paper proposes an order-based consensus model that performs from the search for consistency between preference relations to achieving consensus. For this task, consensus and proximity measures are defined. These measures guide and aid the group dialog stage of the consensus procedure. To validate the pertinency and rationality of the proposed consensus model, a descriptive example is addressed concerning the ranking of possible locations of an electricity power plant in the European Union from the best to the worst.