Explicit approval voting
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)
Approval voting is generally equivalent to 2-level Score voting (where the levels are "0" and "1"). Explicit Approval is equivalent to 2-level Score voting where voters may explicitly abstain, and the default choice is to abstain.
By itself, this rule 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, but hasn't seemed to be a problem in actual elections, despite abstention being common.
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.
Wikimedia and Wikipedia elections are held using an equivalent system, in which voters must choose Support, Oppose, or Neutral for every candidate.
Ballot initiatives and judicial retention elections are similar to Explicit Approval, in that voters may vote Yes, No, or abstain on each option, and they are passed/retained if the Y/(Y+N) ratio is greater than 50%. There is sometimes a quorum participation rule. For example, in Nebraska, a ballot initiative must receive Yes or No votes from at least 35% of those who cast ballots in the general election (less than 65% abstention) to be valid.