Electoral Institutions and Party Cohesion

The impact of electoral institutions on party cohesion is well theorized but the empirical evidence (e.g. Depauw & Martin 2009, Shomer 2017) based only on few case studies or cross-sectional analyses with short time periods. A comprehensive examination of various countries and parties over a larger timescale is missing so far. In this article, I argue that electoral institutions (such as electoral formula and candidate selection procedures) providing candidate-centered incentives lead to a lower level of intraparty cohesion. In contrast, parties are even more cohesive, if it is more promising for candidates to be in line with the party. To test these assumptions in a large-N comparative way, I use an index of party cohesion as my dependent variable not much tested so far. This allows to investigate the relationship between electoral institutions and party cohesion in a time-series cross-sectional (TSCS) manner. The index covers a time period from 1944 to 2016 for 36 countries and about 500 parties. Furthermore, I use a set of independent variables which capture the effects of electoral institutions and incentives for party-centered and candidate-centered behavior. The results confirm the findings of previous studies. Candidate-centered electoral institutions lead to lower level of intraparty cohesion while party-centered institutions imply a higher level of cohesion. Furthermore, the usage of a TSCS cohesion index is appropriated to uncover this relationship.