Dual-member proportional representation

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Dual-member proportional representation (DMP), also known as dual-member mixed proportional, is an electoral system designed to produce proportional election results across a region by electing two representatives in each of the region’s districts.^[1][2] The first seat in every district is awarded to the candidate who receives the most votes, similar to first-past-the-post voting (FPTP). The second seat is awarded to one of the remaining district candidates so that proportionality is achieved across the region, using a calculation that aims to award parties their seats in the districts where they had their strongest performances.

DMP was invented in 2013 by a University of Alberta mathematics student named Sean Graham.^[3] The system was intended as a possible replacement for FPTP in Canadian national and provincial elections. Whereas campaigns to adopt mixed-member proportional representation (MMP) or the single transferable vote (STV) had recently been defeated in a number of Canadian provinces (see 2005 British Columbia referendum, 2005 Prince Edward Island referendum, 2007 Ontario referendum, 2009 British Columbia referendum), the intent behind DMP was to gain broader acceptance by retaining salient features of FPTP. These features include a one-vote ballot, relatively small districts (compared with STV), and a single tier of local representatives (in contrast to MMP).^[4]

Proposals to consider DMP were submitted to the Government of Canada,^[5][6] Alberta,^[7] Prince Edward Island (PEI),^[8] and British Columbia (BC).^[9] In April 2016, the PEI Special Committee on Democratic Renewal officially recommended that DMP appear as one of five options on the 2016 PEI plebiscite, with the winning voting system determined by instant-runoff voting.^{[10][11][12][13]} The plebiscite took place from October 29 to November 7, 2016.^[14][15][16] DMP was eliminated on the third round, and after its votes were redistributed MMP was declared the winner ahead of FPTP.^[17][18] (The referendum was non-binding and the government of the time ignored the result.) In May 2018, DMP was one of three proportional systems selected to appear on the 2018 BC referendum.^[19][20][21] The referendum involved a two-question mail-in ballot to be returned by the extended deadline of December 7, 2018.^[22] On the first question, a 61% majority of voters chose to retain the current FPTP voting system instead of switching to a form of proportional representation. On the second question, which would have decided the specific proportional system, MMP enjoyed the most support, with DMP collecting slightly more first-choice preferences than rural–urban proportional representation.^[23]