User:RobLa/MAF

"majority approval filter" or "MAF" is an approval-based primary election method that advances all candidates who are approved by a majority of the electorate, as well as usually selecting an opposition candidate. Voters use an approval voting ballot to select which candidates would be acceptable to advance to the general election. If most voters engage in bullet voting, it would typically select two candidates to advance to a general election.

Rules

Draft 3

published December 7, 2018

Goal:

Hold a primary election with an Approval Voting-style ballot, providing motivation for all candidates to achieve the highest approval rating, and resulting in a general election Ballot Satisfaction Score of at least 75%. The "Ballot Satisfaction Score" is the percentage of the electorate which approves of at least one candidate on a given ballot.

Candidates advancing to the general election must qualify for one of the following "Pools":

• "Supermajority Candidate Pool" - all candidates who receive greater than 75% approval
• "Plurality Candidate Pool" - all candidates who receive greater than 50% approval, but do not qualify for the Supermajority Candidate Pool. If no candidate receives greater than 50% approval, this pool may contain candidates with less than 50% approval.
• "Opposition Candidate Pool" - a subset of candidates who receive greater than 40% approval, but do not qualify for the Plurality Candidate Pool
  

Candidates that don't qualify for one of the above pools are "Non-advanced Candidates". By default, all candidates are Non-advanced Candidates until they qualify for one of the above Pools.

Rules for filling the above Pools with qualified candidates:

1. Select the candidate who receives the highest approval rating. This is the "Top Candidate" and automatically qualifies for the general election ballot
   • 1a. If the Top Candidate (and any other candidate) receives greater than 75% approval, add this candidate to the Supermajority Candidate Pool
   • 1b. If the Top Candidate receives less than 75% approval, add this candidate to the Plurality Candidate Pool
2. Add all other candidates who receive greater than 50% approval to the Plurality Candidate Pool
3. Evaluate the Ballot Satisfaction Score. If the Ballot Satisfaction Score is greater than 75%, skip to step 5 (candidate selection is complete). If the Ballot Satisfaction Score is less than 75%, proceed to step 4.
4. If there is more than one candidate in the Plurality Candidate Pool, attempt to add an equal number qualified candidates to the Opposition Candidate Pool, evaluating each Non-advanced Candidate using the following steps
   • 4a. Find the Non-advanced Candidate with the highest approval score. If this candidate has less than 40% approval, no further candidates qualify to be added to the Opposition Candidate Pool.
   • 4b. Add the Non-advanced Candidate from the previous step to the Opposition Candidate Pool.
   • 4c. If there are no other Non-advanced Candidates who received greater than 40% approval, or the Opposition Candidate Pool contains an equal number of candidates to the Plurality Candidate Pool, proceed to step 5. Otherwise, skip back to step 3.
5. Candidate selection is complete. Advance all candidates in the Supermajority Candidate Pool, the Plurality Candidate Pool, and the Opposition Candidate Pool to the general election.

See December email thread "[EM] Approval-based replacement for jungle primary" for more discussion about the evolution of this draft.

Draft 2

published November 22, 2018

Rules for Draft 2:

1. Select the candidate who receives the highest approval rating. This is the "top candidate" and qualifies for the ballot
   • 1a. If the top candidate (and any other candidate) receives greater than 75% approval, add these candidates to the "highly-approved candidate pool"
   • 1b. If the top candidate receives less than 75% approval, add the top candidate to the "majority candidate pool"
2. If the top candidate has been added to the "majority candidate pool", also add a candidate to the “opposition candidate pool”. To be added, this candidate must be the candidate which maximizes the "majority/opposition ballot satisfaction". "ballot satisfaction" generally means voters approve of at least one candidate on a given ballot. "majority/opposition ballot satisfaction" is for a ballot that only contains the "majority candidate pool" and the "opposition candidate pool".
3. For each candidate who receives over 50% approval, but less than 75% approval:
   • 3a. Add this candidate to the "majority candidate pool"
   • 3b. Add a candidate to the "opposition candidate pool" who maximizes the "majority/opposition ballot satisfaction" of the electorate (as in step 2)
4. Eliminate all candidates from the "opposition candidate pool" who have an overall approval rating under 25%
5. All candidates remaining in the "highly-approved candidate pool", the "majority candidate pool" and the "opposition candidate pool" advance to the general election.

See 2018-11-22 email from RobLa for further commentary.

Draft 1

published November 20, 2018

Rules for Draft 1:

1. The candidate who receives the highest approval rating (the "front-runner") qualifies for the general election
   • Example: if there are 100 voters, and 40 approve of "A" and "B", 30 approve of only "B", and 30 approve of only "C", then
     • "B" advances to the general election, since "B" is approved by 70% of voters.
2. A second candidate (the "complementary candidate"), who maximizes the approval of the electorate, also qualifies (i.e. by having the highest approval among voters that did not approve of the front-runner). If two candidates both satisfy an equal part of the remaining electorate, the candidate with the highest overall approval rating advances.
   • Example: if there are 100 voters, and 40 approve of both "A" and "B", 30 approve of only "B", and 30 approve of only "C", then
     • "B" advances with 70% approval (per step 1)
     • "C" advances (per this step).  "B" satisfies 70% of the electorate, and "C" satisfies the other 30%.  So, 100% of the voters will be satisfied with one of their choices in the general election.
3. All candidates who receive over 50% approval ("majority approval candidates") also qualify for the general election
   • Example: if there are 100 voters, and 50 approve of "A" and "B", 20 approve of only "B", and 30 approve of only "C", then :
     • "B" advances with 70% approval (per step 1)
     • "C" advances, satisfying the other 30% of the electorate, making the total 100% (step 2)
     • "A" advances as well (having achieved 50% approval)

History of MAF

• 2018-11-20 - first draft published on electowiki.org and as "Replacing the jungle primary" by User:RobLa

Full discussion history of this method can be found at Talk:Majority approval filter

See also

• Maximum approval top-two (MATT) - a simplification of MAF that is guaranteed to advance no more than two candidates.