Mixed Member Proportional

Mixed Member PR systems combine two different electoral systems and allocate some seats to be won in single member ridings (SMP or AV) and others to be awarded by PR from party lists.

For example, Germany and New Zealand allocate half their seats to SMP elections. The other half are filled from party lists. Voters get to have 2 votes, one for their local constituency election and one for the party list.

Party list seats are allocated after the results from the SMP elections are known. The party list seats are then awarded to try to ensure that the combined total of a party’s SMP and list seats will be roughly proportional to their share of the party-list votes.

Example of MMP election for a 100 seat legislature

MMP systems are quite widely adopted, and some countries use the Alternative Vote system instead of SMP for electing the single-member seats.

Different countries allocate different proportions to single-member and party-list seats; i.e. 50-50, 25-75, 75-25 etc.

Some do not try to make the overall share of seats proportional to the vote, but simply award the party-list share strictly according to the share of party vote. These are known as "top up" seats to make the results relatively more proportional than they would have been under SMP or AV, without trying to achieve full proportionality.