Mixed-Member Proportional Representation

Mixed-Member Proportional Representation


Mixed-member proportional representation (MMP) is mixed or “hybrid” because it combines elements of proportional and single-member plurality systems. With MMP, voters have a single MP who represents their riding, while other seats are distributed proportionately to total votes cast in the election.

What family does it belong to?

Where is it used today? MMP is used in nine countries, including Germany and New Zealand. The Scottish Parliament and Welsh Assembly use a version of the system as well.

How does the system work for voters? Voters have two votes: one for a candidate running in their riding, and a second for a party or a candidate on a party list. The riding candidates can be affiliated with a party or run as independents. The members of a party list can either be selected by the party or voted on individually.

How are the ballots counted? The system produces two kinds of MPs, the first elected directly in constituency races, and the second elected via List PR. In most cases, the victors in the constituency races win their seats in the legislature using FPTP, but there is one variation of MMP that uses AV instead. The overall share of seats in the house is determined by the party vote, however.

An electoral formula is used to translate the party vote into the specific number of seats. After the total number of constituency seats won by each party is known, parties are assigned list seats equal to the number of proportional seats they are entitled to in order to “top up” the number of constituency seats won in each geographical region. Simply put, the party vote determines the total number of seats each party receives, and list MPs make up the difference between that total and the number of constituency seats won. Parties’ internal rules typically determine the process used to establish the list candidates and the order that they will be elected. In advance of the election, each party will make a list of candidates to fill out the proportional seats won.

MMP systems often use a minimum vote threshold requiring parties to win a certain share of the vote and/or a certain number of seats. Parties that fail to reach the threshold do not get any seats.

What do ridings look like? MMP provides ridings with individual representatives for part of the seats in the House. The rest of the candidates are elected from a list that each party prepares before the election. Depending on the total number of MPs and the ratio of list to constituency MPs, ridings could be anywhere from the same size to twice as big as they are now.

List MPs are then elected at the regional, provincial or national level, depending on the system design.

How are Parliament and government formed? How is the prime minister selected? The governor general invites any party that receives more than half the seats to form a government. However, it is unlikely a single party would have a majority. More likely, the largest party will lead a minority government, or a coalition of two or more parties would come together to form a government. The prime minister is generally the leader of the largest party in the coalition.

Also known as: MMP; additional member system

What does it mean…

For campaigning? Campaigning is split between the national race and the local races across the country. Candidates running in local constituencies still focus on local issues, but the importance of the party vote means the national campaign is more significant.

2. For vote choice? MMP allows the voter to choose a representative at the constituency level, while voting separately for a party at the national level. Voters can decide whether to vote for a candidate of the same party they are voting for, or support a local candidate of a different party.

3. For local representation? MMP ensures voters have a single representative responsible for their riding and that a party in the legislature represents their perspective, with the exception of voters who support fringe parties.

4. For parties in Parliament? As a proportional system, MMP allows smaller parties to gain seats in the House of Commons, leading to a larger greater number of parties overall. It is for this reason that MMP systems use the threshold rule described above, which limits the ability of fringe parties to win seats.

The system produces two types of elected MPs—constituency and list—each with different motivations. Constituency MPs may pay more attention to local issues, while list MPs focus more on the national party and its agenda. Smaller parties will typically have more MPs elected from lists, whereas larger parties will have more MPs elected by constituencies.

Under MMP, parties can offer lists with proportionate numbers of women, visible minorities and other diverse Canadians, which can increase their representation in Parliament.

5. For governing?
As parties often have to form coalitions to govern, politicians need to work with members from other parties. Party leaders may forge alliances with other parties before an election is held, or wait until after the results are known before agreeing to form a coalition. Accordingly, voters may not know who will be in government even after the votes are counted, as they must wait for a governing coalition to emerge from among the parties. Governments may change when coalitions break down. Members can move to opposition or join other parties to form a new governing coalition.  

What would the ballot look like?


*  This is an example of an MMP ballot using a closed party list. Sometimes in closed lists, the names of the possible candidates from the party appear on the ballot. MMP is also compatible with an open list system, in which the names of list candidates put forward by parties in a given district or region would be voted on to fill any proportional seats won by the party.

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