Part of the Politics and Economics series |
Electoral systems |
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Mixed-member proportional representation (MMP or MMPR) is a mixed electoral system which combines local winner-take-all elections with a compensatory tier of party list votes, which are used to allocate additional members in a way that aims to produce proportional representation overall. In typical MMP systems, voters get two votes: one to decide the representative for their single-seat constituency, and one for a political party. Some countries use single vote variants of MMP, although this article focuses primarily on dual vote versions of MMP.
Seats in the legislature are filled first by the successful constituency candidates, and second, by party candidates based on the percentage of nationwide or region-wide votes that each party received.[1][2][3] The constituency representatives are usually elected using first-past-the-post voting (FPTP). The nationwide or regional party representatives are, in most jurisdictions, drawn from published party lists, similar to party-list proportional representation. To gain a nationwide representative, parties may be required to achieve a minimum number of constituency seats, a minimum percentage of the nationwide party vote, or both.
MMP differs from a type of so called mixed-member majoritarian representation known as parallel voting in that the nationwide seats are allocated to political parties in a compensatory manner in order to achieve proportional election results across all seats (not just the additional seats). Under MMP, two parties that each receive 25% of the votes end up with about 25% of the seats, even if one party wins more constituency seats than the other. Depending on the exact system implemented in a country and the results of a particular election, the proportionality of an election may vary.[4] Overhang seats may reduce the proportionality of the system, although this can be compensated for by allocating additional party list seats to cover any proportionality gap.[5]
MMP was first used to elect representatives to the German Bundestag, and has been adopted by New Zealand and others, with modifications.