Electoral institutions do not change much. Exceptional cases of electoral reform are passionately promoted by the proponents of reform with the claim that reform would make citizens more engaged, more trusting and satisfied with the political system. Notable cases of electoral reform in 1990s like Italy, Japan, New Zealand all happen to adopt more proportional electoral rules. These are particularly attractive since they provide an opportunity of a quasi-experimental research design by comparing the effects of different electoral rules in for the same polity. New Zealand is even more attractive since survey data documenting preferences and attitudes of citizens in different elections is available. Change in the electoral system lead various studies to investigate effects of change in political institutions to party competition, strategic voting, issue voting and candidate effects in New Zealand. However it has not been investigated from the perspective of ideological congruence. This paper would analyze if and how the fit between ideological preferences of voters and representatives (namely ideological congruence) in the system co-evolve with institutional factors. The analysis of New Zealand as a quasi- experimental case study would answer an important concern of ideological congruence studies; whether certain electoral institutions are more conducive to congruence than others. Data availability allows us both to compare two elections before and after the electoral system change and to see how congruence changed in consecutive elections before and after the system change in a longitudinal fashion. New Zealand Election Study is the main data source. Separate voter and candidate surveys of NZES provides an opportunity to compare voter preferences directly with preferences of representatives. Data will be analyzed with multilevel hierarchical models in order to account for individual and system level factors.
