Explicit approval voting

From Electowiki
Jump to navigation Jump to search
An explicit approval ballot on which the voter has not expressed any abstentions

Explicit approval voting is a rated voting system which is essentially Approval voting with abstentions. In order to allow abstention, voters must explicitly state disapproval. So, the ballot will list Approve and Disapprove for each candidate, and leaving a candidate without either mark represents abstention. The winner is the candidate who has the highest approval among those who didn't abstain: A/(A+D)[1]

By itself, this leads to the possibility of an unknown dark horse candidate winning with only a few approve votes and many abstentions. This can be prevented through the use of various quorum rules,[1][2][3] but hasn't seemed to be a problem in actual elections, despite abstention being common.

Usage[edit | edit source]

Wikimedia and Wikipedia elections are held using an equivalent system, in which voters must choose Support, Oppose, or Neutral for every candidate. The winner is the candidate with the highest support percentage: the highest proportion of Support votes out of combined Support and Oppose votes = S/(S+O).

Approval voting is generally equivalent to 2-level Score voting (where the levels are "0" and "1"). Wikimedia's variant is equivalent to 2-level Score voting where voters may explicitly abstain, and the default choice is to abstain. The levels in Wikimedia's system imply (−1, +1) rather than (0, 1), so they may be affected by the psychological consequences of disapproval voting.[4]

The Wikimedia Foundation has used this method for Board of Trustees and Funds Dissemination Committee elections in 2013, 2015, and 2017, after previously using Approval voting and Schulze method. Wikipedia uses this in a non-binding way for Administrator nominations,[5] etc.

Analysis[edit | edit source]

If tallied using normal Score voting rules (where O=0, N=1, S=2), the 2015 Wikimedia Board election would have had a different winner, with the candidate in 4th place moving up to 2nd. The 2017 Board and 2015 FDC elections would have had a different top-3 order, but the same 3 candidates would have won.

In all 8 elections from 2013-2017, the most common vote was Neutral, which was cast about twice as often as Support, which in turn was cast about twice as often as Oppose. Winners typically receive 70–85% support.

While Explicit Approval and Combined Approval have equivalent ballots, they are not tallied the same. For example, if Candidate A received 5 Approvals and 5 Abstentions, while Candidate B received 9 Approvals and 1 Disapproval:

  • Under Explicit Approval, Candidate A would win, with 5/(5+0) = 100% support, vs Candidate B's 9/(9+1) = 90% support.
  • Under Combined Approval, Candidate B would win, with 9-1 = 8 points vs Candidate A's 5+0 = 5 points.

References[edit | edit source]

  1. a b "Explicit Approval & Hybrid Approval voting". r/EndFPTP subreddit. Retrieved 2019-08-12. 
  2. "Averaging". RangeVoting.org. Retrieved 2019-08-12. 
  3. "Better "Soft Quorum" Rule". RangeVoting.org. Retrieved 2019-08-12. 
  4. See also Wikipedia:Combined approval voting#Properties, in particular the Baujard citation
  5. w:Wikipedia:Requests for adminship#Decision process