Legislative organization in MMP: The case of New Zealand

How do electoral systems affect legislative organization? The change in electoral systems from Single Member District plurality (SMD) to Mixed Member Proportional (MMP) in New Zealand can illuminate how electoral incentives affect the distribution of cabinet positions. Because in SMD the outcome of individual local districts determines the number of seats a party wins collectively, New Zealand parties deploy cabinet posts in order to shore up the electoral fortunes of individual members. In MMP, the total number of seats a party receives is determined by the votes in the proportional representation (PR) portion for the party, which eliminates the incentives to reward electorally unsafe members with cabinet positions. We show that strong cabinet members, measured through experience as prior terms in the cabinet position, are still likely to be retained.