Determinants of legislative turnover in Western Europe, 1945–2015

This article explains legislative turnover in eight West European legislatures over 152 general elections in the period 1945–2015. Turnover is measured as the rate of individual membership change in unicameral or lower chambers. It is the outcome of a legislative recruitment process with a supply and a demand side. Decisions made by contenders affect supply, while decisions made by parties and voters influence demand. Such decisions are shaped by four political and institutional factors: the institutional context of political careers, or structure of political career opportunities; political party characteristics; electoral swings; and electoral systems. Ten specific hypotheses are tested within this theoretical framework. The structure of political career opportunities is the most decisive factor explaining variability in turnover rates, followed by electoral swings and political parties. Electoral systems show less substantive effects. Electoral volatility is the predictor with the most substantive effects, followed by duration of legislative term, strength of bicameralism, regional authority, gender quotas, level of legislative income and district magnitude.