Fiona Barker and Elizabeth McLeay, "How Much Change? An Analysis of the Initial Impact of Proportional Representation on the New Zealand Parliamentary Party System," Party Politics, 6 (April 2000), 131-154.

First Paragraph:
Before New Zealand adopted proportional representation (PR) it was a textbook example of single-party majority government and adversarial politics. Under the simple plurality, single-member-constituency electoral system New Zealand had a political executive unencumbered by the major veto points (Kaiser, 1997) of federalism--a written constitution, an upper house, or a powerful judiciary. The only fetter to the power of a governing party was the triennial general election, a restraint acknowledged as significant by voters when in referendums in 1967 and 1990 they voted to reject elite proposals for a 4-year term. In 1993, the citizens again voted in a binding referendum, this time to change their electoral system (Royal Commission on the Electoral System, 1986; Catt et al., 1992; Hawke, 1993; McRobie, 1993; Palmer and Palmer, 1997). The story of this radical change is complex and is not related here (see McRobie, 1993; Vowles et al., 1995; Boston et al., 1996a, 1996b; Jackson and McRobie, 1998). Table 1 sets out the major features of the two electoral systems, first-past-the-post (FPP) and mixed- member proportional (MMP).

Figures and Tables:
Table 1: New Zealand's electoral system
Table 2: The New Zealand parties under FPP: votes and seats, 1984-1993
Table 3: The 1996 general election: votes and seats
Table 4: New Zealand political parties and issue dimensions at the 1996 election

Last Paragraph:
New Zealand provides an excellent case study of the effects of electoral system change on a political system. Because it is a stable and long-established democracy with a mature party system, the effects of PR can be easily monitored and fairly easily assessed. In short, the electoral system variable can be isolated in so far as any one political variable can be isolated anywhere. Nevertheless, the New Zealand story acts as a cautionary tale to reformers and political scientists alike: electoral systems are embedded in other institutions and practices and it is not always easy to disentangle one from the other.