Transformational party events and legislative turnover in West European democracies, 1945-2015

This paper examines the influence of party change on party-level legislative turnover. Analyzing a novel dataset tracking 251 parties in eight West European democracies between 1945 and 2015, we assess how transformational party events affect the renewal of parties’ parliamentary delegations. Transformational party events refers to party changes resulting from deliberate strategic decisions that redistribute power within parties, change their identity, and/or shift alliances within and between them. We focus in particular on changes in parties’ leadership and name, the formation of electoral cartels, mergers and divisions, applying empirical methods suitable for dealing with fractional outcomes and multi-level data to test their impact on turnover rates. Our estimates indicate that leadership change is a key determinant of MP renewal, leading to systematically higher rates of legislative turnover. Party relabeling and divisions affect turnover as well, although their influence is contingent on other characteristics of the parties and their environment.