Ranked Approval Voting

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Revision as of 21:28, 9 September 2005 by KVenzke (talk | contribs) (not a method but a DMC heuristic.)

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Ranked Approval Voting (RAV) is one heuristic for finding the Definite Majority Choice winner. Kevin Venzke may have been the first to suggest it on the election methods mailing list, in September 2003. It was given the name "Ranked Approval Voting" by Russ Paielli.

Ballot Format

To implement RAV, a voter uses a ranked ballot. By default, any ranked candidates are considered approved. Depending on implementation, the voter may also add an approval cutoff to indicate that some of the ranked candidates are not approved.

Procedure

Ballots are tabulated into a pairwise matrix.

Repeat until a winner is found:

  • Search for a candidate who is not defeated by any other non-eliminated candidates. If one is found, this is the RAV winner..
  • If no RAV winner exists, the candidate with the least approval is eliminated —his pairwise contests are no longer considered.

The process repeats until some non-eliminated candidate pairwise defeats every other non-eliminated candidate.

Ranked Approval Voting is a Condorcet method, which means it always finds the Condorcet winner if one exists. A Condorcet winner is the candidate who, when compared in turn with each of the other candidates, is preferred by more voters to the other candidate. This implies that a majority of ballots rank the CW above any other candidate.

Advantages

Ranked Approval Voting satisfies the Smith criterion without requiring an explicit step to reduce to the Smith set.