Career lengths of members of parliament in mixed-member proportional electoral systems

Mixed-member proportional electoral systems are characterised by having two types of members of parliament (MPs): district MPs elected directly in a district and list MPs elected via a party list. While it has been suggested that district MPs have a more prestigious and safe position than list MPs, little is known about possible differences between list and district MPs in terms of the length of their parliamentary careers. Using data on all New Zealand parliamentary elections between 1996 and 2017, the authors investigate to what extent the mode in which MPs are elected throughout their careers relates to the length of their careers. The authors' descriptive and multivariate Cox Proportional-Hazards analyses show that those entering parliament as list MPs have shorter careers than those entering parliament as district MPs. However, when list MPs 'move on' to becoming district MPs during their parliamentary career, they have the longest careers of all MPs.