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 often selecting one or more opposition candidates.

Definition

Draft 4 published December 28, 2018

This set of rules is broken into three parts: 1) The goal of MAF, 2) the definition of "Pools" of candidates advanced to the general election in this system, and 3) the rules for populating the Pools of candidates. It is written with some effort toward legal precision and legal document tools-of-the-trade (e.g. the use of capitalized "defined terms"), but more work is needed.

Goal

A set of rules for holding 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.

Pools

Candidates advancing to the general election must qualify for one of the following "Pools". Candidates that don't qualify for one of the Pools below are "Non-advanced Candidates". By default, all candidates are Non-advanced Candidates until they qualify for one of these 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 will contain the leading candidate, who may have 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

Rules

Sequential steps 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 by one of the following rules:
   • 1a. If the Top 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. Complete the Supermajority Candidate Pool and the Plurality Candidate Pool using the following rules:
   • 2a. Add any Non-advanced Candidates with greater than 75% approval to the Supermajority Candidate Pool
   • 2b. Add any Non-advanced Candidates with less than 75% approval, but greater than 50% approval to the Plurality Candidate Pool
3. Evaluate the Ballot Satisfaction Score (defined above) using the following rules:
   • 3a. If the Ballot Satisfaction Score is greater than 75%, candidate selection is complete. Skip to step 5
   • 3b. If the Ballot Satisfaction Score is less than 75%, proceed to step 4.
4. If there is one or more candidates 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, determine if this candidate qualifies for the Opposition Candidate Pool in step 5.
     • If this candidate has greater than 40% approval, add this candidate to the Opposition Candidate Pool, then proceed to step 4b.
   • 4b. Compare the size of the Plurality Candidate Pool and the Opposition Candidate Pool
     • If the Plurality Candidate Pool has more candidates than the Opposition Candidate Pool, skip back to step 3.
     • If the Opposition Candidate Pool contains an equal number of candidates to the Plurality Candidate Pool, proceed to step 5.
5. If the Ballot Satisfaction Score is greater than 50%, skip to step 6. If the Ballot Satisfaction Score is under 50%, ensure at least two candidates advance to the general election using the following steps:
   • 5a. If there are no candidates in the Opposition Candidate Pool, find the Non-advanced Candidate with the highest approval score. If this candidate increases the Ballot Satisfaction Score by more than 10% (the "Candidate Differentiation Threshold"), add this candidate to the Opposition Candidate Pool, and skip to step 6. Otherwise, advanced to step 5b.
   • 5b. Consider each Non-advanced Candidate in order of approval score. Find the first candidate who increases the Ballot Satisfaction Score by more than the Candidate Differentiation Threshold (10%), and add this candidate to the Opposition Candidate Pool, and skip to step 6. Otherwise, advance to step 5c.
   • 5c. Find the Non-advanced Candidate with the highest approval rating. Add this candidate to the Opposition Candidate Pool, and advance to step 6.
6. 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.

History of MAF

• 2018-12-28 - Draft 4 published at <https://electowiki.org/wiki/MAF>, based on conversation documented at Talk:Majority approval filter
• 2018-12-07 - Draft 3 published (with clarifying edits continuing through 2018-12-10). See December email thread "[EM] Approval-based replacement for jungle primary" for more discussion about the evolution of this draft
• 2018-11-22 - Draft 2 published in 2018-11-22 email from RobLa (and also avaiable at User:RobLa/MAF drafts#Draft_2
• 2018-11-20 - first draft published on electowiki.org and as "Replacing the jungle primary" by User:RobLa (and also available at User:RobLa/MAF drafts#Draft_1)

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.