Coombs' method: Difference between revisions

Revision as of 00:14, 19 October 2022

Revision as of 05:23, 20 October 2022

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{{Electoral systems}}

'''Coombs' method''' (or the '''Coombs rule''')<ref name=Grofman>Grofman, Bernard, and Scott L. Feld (2004) [https://dx.doi.org/10.1016/j.electstud.2003.08.001 "If you like the alternative vote (a.k.a. the instant runoff), then you ought to know about the Coombs rule,"] ''Electoral Studies'' '''23''':641-59.</ref> is a [[ranked voting systems|ranked voting system]] is a ballot counting method for [[ranked voting]] created by [[Clyde Coombs]]. Theused Coombs'for method is the application of Coombs rule to [[Single-member district|single-winner [[election]]s,. similarlySimilarly to [[instant-runoff voting]], it uses candidate elimination and redistribution of votes cast for that candidate until one candidate has a majority of votes. The Coombs rule can be applied to [[Multiwinner voting]] and in difference to [[Single transferable vote]] selects the [[Condorcet winner criterion|Condorcet winner]].<ref name=Grofman/>

==Procedures==

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==Potential for strategic voting==

The Coombs rule always selects the [[Condorcet winner criterion|Condorcet winner]].<ref name=Grofman/>

The Coombs' method is vulnerable to three [[tactical voting]] strategies:{{Citation needed|date=January 2008}} [[Tactical manipulation of runoff voting#Compromise|compromising]], [[Tactical manipulation of runoff voting#Push over|push-over]], and [[strategic nomination|teaming]]. Coombs is sensitive to [[Instant-runoff voting#Invalid ballots and incomplete ballots|incomplete ballots]], and how voters fill in the bottom of their ballots makes a big difference.<ref>[http://www.accuratedemocracy.com/l_data.htm "Data on Manipulability"]</ref>