Replication Data for: From Duverger to the Seat Product: Seeking a Pattern in Experts’ Evaluation of Electoral Systems

Widely influential Duverger’s “law” and “hypothesis” describe the main direction of influence of electoral rules on party systems, however, their formulations are quite blurry what makes their application to concrete electoral results often ambiguous. Therefore, this research conducted an original survey among electoral experts (n=131) to explore whether they apply Duverger’s rule in a consistent pattern which could lead to its less ambiguous specification. Experts’ responses revealed a considerable heterogeneity which indicates that their evaluation of electoral systems is not driven by an unambiguous theoretical framework. Nevertheless, experts were on average consistent with the quantification of the Duverger’s rule done by Taagepera (2007) in Seat Product Models which served as benchmarks for this study. Therefore, this research concludes that the Seat Product Models constitute a suitable specification of the Duverger’s logic which should be used as a baseline in electoral studies. The reason is that the Models allow more fine-grained evaluation of electoral systems, while being already consistent with experts’ perception of electoral system effects.