Dual-member mixed proportional

[4] It is similar to other forms of mixed-member proportional representation, but differs from the better-known additional-member system in that all representatives are elected locally in small districts, rather than requiring separate list seats to be filled in large regional or nationwide districts.

In the second step, underrepresented parties are assigned secondary seats in the districts in which they won the most votes, which creates an overall proportional result.

DMP was invented in 2013 by a University of Alberta mathematics student named Sean Graham.

[5] The system was intended as a possible replacement for single-member plurality (SMP) in Canadian national and provincial elections.

These features include a one-vote ballot, small districts (unlike with STV), and a single tier consisting only of local representatives (in contrast to other MMP proposals).

Proposals to consider DMP were submitted to the Government of Canada,[2][7] Alberta,[8] Prince Edward Island (PEI),[9] and British Columbia (BC).

[14][15][16] DMP was eliminated in the third round, and after its votes were redistributed, MMP was declared the winner (ahead of FPTP).

[22] On the first question, a 61% majority of voters chose to retain the current FPTP voting system instead of switching to proportional representation.

Both DMP and conventional MMP can be considered mixed electoral systems, meaning that two types of calculation methods are combined.

Of the various forms of MMP, DMP has most in common with the "best near-winner" system (second mandate, Zweitmandat) used in the German state of Baden-Württemberg.

[24] Whereas most implementations of MMP provide electors with two votes, both DMP and the Baden-Württemberg system employ a one-vote ballot.

Thus while the DMP calculation is comparable to that of conventional MMP, the resulting form of governance is similar to that of the single transferable vote and other systems based on multi-seat districts.

This makes it related to the concept of biproportional apportionment, which uses a unified algorithm for determining how many seats represent each region and to achieve party proportionality on the whole based on the votes cast.