MMP (Mixed Member Proportional) was the recommendation of the 2007 Ontario Citizens’ Assembly on Electoral Reform – it uses single member ridings + top-up seats, and normally uses a two-part ballot (local + list). DMP (Dual Member Proportional) is a variant currently being considered in PEI.

In 2007, the Ontario Citizens’ Assembly on Electoral Reform recommended adoption of the Mixed Member Proportional (MMP) system because they felt it best matched their top values:  (1) greater voter choice, (2) fairer election results, and (3) stronger representation.

What is MMP?

The Mixed Member Proportional (MMP) voting system was introduced in Germany following the Second World War and is currently used at the national level in Germany, New Zealand, Lesotho and Bolivia. It is also used for the Scottish and Welsh devolved parliaments.

MMP is a two-tier voting system in which a majority of MPs (typically about 60%) are elected in single-member districts, much the way we do now, and the remainder are elected off party lists on a compensatory basis at a regional or national level to minimize the discrepancy between vote share by party and the corresponding seat share. In an “open list” MMP system, the top regional vote-getters from under-represented parties fill top-up seats until those parties’ share of seats reflects their share of the popular vote. In the flexible list version recommended by the Law Commission of Canada, the party would put forward a list of candidates and voters could potentially override the party’s order if enough voters (e.g., the LC recommended 8% of the total party vote) selected a particular candidate.

The graphic below illustrates the key ideas behind MMP:

Overview of Mixed Member Proportional voting (courtesy of Library of Parliament)

MMP has a track record for electing more women than are normally elected under SMP voting systems. In Germany, 36.5% of parliamentarians are women, while in New Zealand, 31.4% are (compared with Canada at 26%).

For a more complete discussion about MMP, please visit our companion website, MMPforCanada (note that although FVBC does not explicitly endorse one voting system over another, we regard MMP as a first-rate option for Canada, especially if voter choice is maximized through using open lists). We also recommend Wilf Day’s blog site – Wilf is on the board of Fair Vote Canada and has an encyclopedic knowledge of MMP voting systems.

How MMP Works

As described above, MMP is a two-tier voting system in which approximately 60% of the seats are in single member ridings, much they way they are with our current system. If Canada were to elect our 338 MPs using MMP, approximately 200 of the seats would be in this first tier.

The remaining ~140 seats would be arranged in a second tier either by province (for the smaller provinces) or by regions within the larger provinces. For example, on Vancouver Island, which has 7 seats, we might create four single-member ridings (two near Victoria, one in the southern to mid-island, and one in the northern part), along with three regional seats. In a more densely populated area such as the Lower Mainland, which has 26 seats, we might create about 18 single-member ridings (roughly two replacing every three current ridings) and then have 8 regional seats. In the Interior (9 current seats), we might create six single-member ridings and elect three members region-wide. Of course, the ultimate choice of electoral boundaries and mix of single-member and regional seats would be the responsibility of a non-partisan Electoral Boundaries Commission, just as it is with our current system.

National Results Using MMP

We simulated the effect of using MMP in the last federal election.  Recognizing that we had to make a number of assumptions for this exercise, including the assumption that voter behaviour wouldn’t change significantly (which it likely would if we were using a voting system that encouraged more honest voting), we estimate that, had voters voted roughly as they did in 2015, then, as shown by Anita Nickerson (with Fair Vote Canada), with an MMP model that uses an average of 5 single-member seats and 3 top-up seats per region, the Liberal Party would likely have won about 43% of the seats on 40% of the vote (instead of the 54% they won under our current system), the Conservatives would have won about 32% of the seats on 32% of the vote, the NDP 21% of the seats on 20% of the vote (instead of only 13%), the Bloc 4% on 5%, and the Greens <1% on 3%.  Overall, the results would have much more accurately reflected how voters actually cast their votes, and we would have largely eliminated the regional imbalances – there would have been Conservative and NDP MPs elected in Atlantic Canada, Liberal MPs elected across the Prairies and in the BC Interior, and Conservatives elected on Vancouver Island.  And even though the Liberal Party might have won a few more seats than their share of the vote might have suggested, they would not have won nearly such a large bonus and would have to collaborate with one or more of the other parties in order to pass legislation.

Making MMP More Proportional

As noted above, the Green Party would not likely have won many more seats under the moderate form of MMP described above. This is because their supporters are very diffusely distributed, rarely representing more than 5% of the voters in any given region. Since the MMP regions used in the model had about 8 seats, Green Party supporters can only elect a Green MP in areas where they constitute about one seat’s worth of voters (about 10-12% in an 8-seat region). For Green supporters to be able to elect more MPs when they only constitute about 5% of the voting population, there has to be some mechanism that would allow them to consolidate their votes from over a broader region. Fortunately, this is quite easily done – in principle, all we have to do is to expand the size of the region. For example, if we used 14 seat regions (comprised of say 9 single-member ridings and 5 top-up seats), then Green Party supporters would likely have elected about 10 MPs instead of just one, so it would have been effective in enabling these voters to elect their preferred candidates. It would have achieved this by slightly reducing the number of Liberal, Conservative and NDP MPs elected – by about 1% each – which would have, on average, brought the seat shares of these parties slightly closer to their actual vote shares, so the overall result would have been fairer. FVBC therefore feels that MMP-14 would be an excellent choice for Canada to adopt.

Dual Member Proportional (DMP)

Dual Member Proportional (DMP) is a variant of MMP that was recently proposed for use in Prince Edward Island; it will be on the ballot in this fall’s plebiscite there.

With DMP, existing single-member ridings will be paired to create new dual-member ridings. Parties will put forward two candidates per riding, and voters will be asked to mark an ‘X’ beside their preferred party’s pair of candidates. One seat in each riding will be awarded to the first-listed candidate of the party receiving the most votes, much the way we do now. The second seats in all ridings would then be filled sequentially on a compensatory basis, starting with the party that needs the most top-up seats. The specific candidate elected in each round would be the strongest remaining candidate, as measured by number (or percentage) of votes received in their riding.

Overall, DMP will deliver results similar to an MMP system with a 50-50 mix of constituency and regional seats, but uses only a single ballot and replaces the top-up region with a process for assigning the top-up MPs to local constituencies. Each voter will therefore live in a two-MP district that will contain the local top vote-getter and a second MP who will usually be from a different party.

In our view, DMP is as proportional as more conventional forms of MMP with province-wide top-up regions (as measured by discrepancy between vote and seat shares earned by candidates of the different parties). Advocates of DMP particularly value the local connections of the top-up MPs, as compared to the broader regional mandates of the top-up MPs under other MMP variants, as well as the simpler one-part ballot. FVBC feels that either DMP or MMP would be equally good choices for Canada.