Two types
Shugart and Wattenberg (2001) classified mixed-member systems by how the district and list tiers are linked. In compensatory systems such as Germany and New Zealand, party vote shares set total seats and list seats top up district winners, producing results close to proportional representation. Japan's parallel system counts the tiers separately, favoring large parties strong in districts and producing more majoritarian results.
Contamination effects
Herron and Nishikawa (2001) proposed that the mere presence of a list vote changes district competition. Small parties run district candidates to boost their list vote, so district races have more parties than Duverger's law predicts. Cox and Schoppa (2002) found such interactions in Germany, Japan and Italy, and Ferrara and colleagues (2005) synthesized the evidence.
Assessments and debates
Moser and Scheiner (2004) argued that comparing the two tiers within one country offers a relatively clean view of system effects but noted that contamination limits this comparison. Split-ticket voting between district and party can involve strategic voting (Cox, 1997). Under compensatory systems, large parties creating satellite parties to defeat the compensation mechanism has also emerged as a problem.
FAQ
- What is a mixed-member system in simple terms?
- Voters cast one vote for a district candidate and one for a party, and the two results are combined to allocate seats.
- How do compensatory and parallel systems differ?
- Compensatory systems adjust total seats to match party vote shares, while parallel systems simply add district and list seats together.
Sources reviewed: 2026-10-26
References
- Shugart, M. S., & Wattenberg, M. P. (Eds.). (2001). Mixed-member electoral systems: The best of both worlds? Oxford University Press. The defining comparative volume.
- Moser, R. G., & Scheiner, E. (2004). Mixed electoral systems and electoral system effects: Controlled comparison and cross-national analysis. Electoral Studies, 23(4), 575–599. Controlled comparison within mixed systems.
- Herron, E. S., & Nishikawa, M. (2001). Contamination effects and the number of parties in mixed-superposition electoral systems. Electoral Studies, 20(1), 63–86. Contamination effects.
- Cox, K. E., & Schoppa, L. J. (2002). Interaction effects in mixed-member electoral systems: Theory and evidence from Germany, Japan, and Italy. Comparative Political Studies, 35(9), 1027–1053. Germany, Japan and Italy compared.
- Ferrara, F., Herron, E. S., & Nishikawa, M. (2005). Mixed electoral systems: Contamination and its consequences. Palgrave Macmillan. Book-length treatment of contamination.
- Lijphart, A. (1990). The political consequences of electoral laws, 1945–85. American Political Science Review, 84(2), 481–496. Consequences of electoral laws.
- Cox, G. W. (1997). Making votes count: Strategic coordination in the world's electoral systems. Cambridge University Press. Strategic coordination.