Using a hierarchical properties ranking with AHP for the ranking of electoral systems

Electoral systems are complex entities composed of a set of phases that form a process to which performance parameters can be associated. One of the key points of every electoral system is represented by the electoral formula that can be characterized by a wide spectrum of properties that, according to Arrow’s Impossibility Theorem and other theoretical results, cannot be all satisfied at the same time. Starting from these basic results the aim of this paper is to examine such properties within a hierarchical framework, based on Analytic Hierarchy Process proposed by T. L. Saaty (Saaty (1980)), performing pairwise comparisons at various levels of a hierarchy so to get a global ranking of such properties. Since any real electoral system is known to satisfy some of such properties but not others it should be possible, in this way, to get a ranking of the electoral systems according also to the political goals both of the voters and the candidates. In this way it should be possible to estimate the relative importance of each property with respect to the final ranking of every electoral formula.