The French and the American school in multi-criteria decision analysis

The paper addresses a crucial problem in multi-criteria analysis: the transition from the objective evaluation of the decision alternatives to the subjective weighing. The French school represented by the ÉLECTRE systems of Roy, and the American school represented by Saaty’s Analytic Hierarchy Process (AHP), incorporate subjective human judgement in different ways. The present paper introduces a thoroughly revised AHP to demonstrate that the American school did not go far enough, so that its potential is somewhat overestimated. Using the persistent pattern of human comparative judgement in many unrelated areas such as history, planning, and psychophysics, it shows that there is a natural scale to quantify verbal preferential statements of increasing intensity. Moreover, the paper analyzes the assumptions underlying the logarithmic-regression procedure to compute the impact scores and the criterion weights. Violations of these assumptions imply that it does not merely supply decision support in order to identify the pre-existing consensus in a group of decision makers. The decision process is reformed by accelerating the deliberations in the direction of a compromise solution. Sensitivity analysis based on a variety of geometric scales shows that the results of the French and the American school of thinking are unexpectedly close to each other.