Fit for parliament: a new index of electability, assessing the electoral success of group-based parties

The openness of the political system for the representation of social or economic groups through their parties is mired in complexities. Extant scholarship has identified multiple electoral system hurdles that jointly determine the institutional opportunities for group representation: This article offers a simple metric to the institutional parts of the political opportunity structure for the electoral representation of social groups. A single variable summarizes the institutional opportunities for group representation, as determined jointly by electoral rules, the demographic structure of ethnic minority groups and their electoral geography. This new Index of Electability considers recent innovations in electoral rules, such as mixed electoral systems, legal thresholds or quotas, which occur in most contemporary democracies. Empirically, the index is applied to ethnic minority parties in 57 plural democracies worldwide. It shows that our index highlights the necessary conditions for parliamentary representation of minorities through their own parties. Contrary to widespread belief that many minority groups form ethnic parties, only one out of three ethnic minority groups worldwide which could, in principle, do so, actually form such a party.