Replication data for: Electoral Reform, Values and Party Self-Interest

It is often taken for granted that parties support electoral reform because they anticipate seat payoffs from the psychological and mechanical effects of the new electoral system. Although some studies point out that elements related to values and the willingness to achieve social goals are also relevant to explain party preference in those situations, a general model of how these considerations influence the support for electoral reform is still missing. To fill this gap, I develop in this article a policy-seeking model accounting for values-related factors and operationalize it using one of the most firmly established effect of electoral systems in the literature: The degree of inclusiveness and its consequences for the representation of social groups in parliament. The empirical relevance of this model is then tested using an original dataset reporting the actual position of 115 parties facing 22 electoral reforms proposals in OECD countries since 1961. The results show that the willingness to favor the electoral system most in line with parties electoral platform has a unique explanatory power for party support for a more proportional electoral system. In turn, values appear to be as crucial as party self-interest to explain the overall electoral reform story.