Coombs' method

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Coombs' method or the Coombs rule^[1] is a ranked voting system which uses a ballot counting method for ranked voting created by Clyde Coombs. Coombs' method can be thought of as a cross between instant-runoff voting and anti-plurality voting.

Like instant runoff, Coombs' method candidate elimination and redistribution of votes cast for that candidate until one candidate has a majority of votes. However, unlike instant-runoff, each round eliminates the candidate rated last by the most voters (instead of first by the fewest voters).

The method satisfies the majority criterion, the pareto criterion, and the Condorcet loser criterion, but fails to satisfy both later-no-harm and later-no-help. The method also fails the Condorcet criterion, the monotonicity criterion, and Independence of irrelevant alternatives.^[2][3]