Another way of looking at group decision making opens new perspectives

Group Decision Support Systems usually use a multiple criteria method as an engine to obtain the group’s ranking of the alternatives. Intermediate results of this multiple criteria method are aggregated over the different group members to come to a final result. Another approach consists of considering the different rankings of the alternatives -one ranking for each group memberand to find the ranking that best fits these different rankings. Hereto, a measurement must be defined that indicates how well a ranking fits a given set of rankings. The problem then reduces a combinatorial optimisation problem since for a given number of alternatives, the number of possible rankings, including the possibilities of ties, is defined in a combinatorial way. In this paper such a measurement is defined. It also explores the new perspectives this approach offers to group decision making.