Coombs' method
Coombs' method (or the Coombs rule)[1] is a ranked voting system created by Clyde Coombs used for single-winner elections. Similarly to instant-runoff voting, it uses candidate elimination and redistribution of votes cast for that candidate until one candidate has a majority of votes.
Example[edit | edit source]
Coombs' method frequently selects the Condorcet winner. However, this does not always happen. For example:
7:a>c>d>b 6:a>d>b>c 3:b>a>c>d 7:b>c>a>d 9:b>c>d>a 4:c>a>d>b 6:d>a>b>c 3:a>c>b>d
This example, placed in Rob LeGrand's voting calculator, shows that Coombs arrives at a different result than Condorcet. The example is pulled from a Felsenthal and Tideman paper.[2]
Links[edit | edit source]
- 1996
- 2005
- https://web.archive.org/web/20050909092356/http://condorcet.org/emr/methods.shtml#Coombs - 2005 archive of Condorcet.org glossary of terminology
- 2019
- https://imgur.com/gallery/SLTHgCO - Diagram of Coombs' and center squeeze
- 2020
Footnotes[edit | edit source]
- ↑ Grofman, Bernard, and Scott L. Feld (2004) "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.
- ↑ Felsenthal, Dan; Tideman, Nicolaus (2013). "Varieties of failure of monotonicity and participation under five voting methods" (PDF). Theory and Decision. 75 (1): 59–77.
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