Center squeeze: Difference between revisions

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The '''center squeeze effect''' refers to a class of voting scenarios which are troublesomedifferent for manyplurality-based voting systems like [[instant-runoff voting]]. In such a scenario, the candidates exist along some spectrum from "left" to "right", with a "center" candidate who is the [[Condorcet winner]] and/or [[utilitarian winner]], yet who loses the election.<ref name=":0">{{Cite journal|last=Lewyn|first=Michael|date=2012|title=Two Cheers for Instant Runoff Voting|url=https://papers.ssrn.com/abstract=2276015|language=en|location=Rochester, NY|journal=6 Phoenix L. Rev.|volume=117|pages=|via=|quote=third place Candidate C is a centrist who is in fact the second choice of Candidate A’s left-wing supporters and Candidate B’s right-wing supporters. ... In such a situation, Candidate C would prevail over both Candidates A ... and B ... in a one-on-one runoff election. Yet, Candidate C would not prevail under IRV because he or she finished third and thus would be the first candidate eliminated}}</ref><ref name=":2">{{Cite journal|last=Merrill|first=Samuel|date=1985|title=A statistical model for Condorcet efficiency based on simulation under spatial model assumptions|url=http://dx.doi.org/10.1007/bf00127534|journal=Public Choice|volume=47|issue=2|pages=389–403|doi=10.1007/bf00127534|issn=0048-5829|quote=the 'squeeze effect' that tends to reduce Condorcet efficiency if the relative dispersion (RD) of candidates is low. This effect is particularly strong for the plurality, runoff, and Hare systems, for which the garnering of first-place votes in a large field is essential to winning|via=}}</ref><ref>{{Cite journal|last=Merrill|first=Samuel|date=1984|title=A Comparison of Efficiency of Multicandidate Electoral Systems|url=http://dx.doi.org/10.2307/2110786|journal=American Journal of Political Science|volume=28|issue=1|pages=23|doi=10.2307/2110786|issn=0092-5853|quote=However, squeezed by surrounding opponents, a centrist candidate may receive few first-place votes and be eliminated under Hare.|via=}}</ref><ref>{{Cite journal|last=Stensholt|first=Eivind|date=2015-10-07|title=What Happened in Burlington?|url=https://ideas.repec.org//p/hhs/nhhfms/2015_026.html|journal=Discussion Papers|language=en|pages=13|quote=There is a Condorcet ranking according to distance from the center, but Condorcet winner M, the most central candidate, was squeezed between the two others, got the smallest primary support, and was eliminated.}}</ref>
 
Many consider that the Condorcet winner (the candidate that would beat any other candidate in a head-to-head election) or utilitarian winner (the candidate rated most highly by the electorate) is the rightful winner of an election. Failing to select this candidate can encourage strategy (typically, [[Favorite betrayal criterion|favorite betrayal]]) from one of the other groups. Note, however, that any voting method avoiding center squeeze can also incentivize strategy if one of the wings thinks they can squeeze out victory for their preferred candidate (i.e., if the "left wing" [[Bullet vote|bullet votes]] in [[Approvalapproval voting]], see [[Chicken dilemma]]).
 
Voting systems that suffer from the center-squeeze effect exhibit a bias in favor of more extreme candidates, which leads to unrepresentative winners and political polarization.<ref name=":3">{{Cite book|url=https://link.springer.com/10.1007/978-3-642-02839-7|title=Handbook on Approval Voting|date=2010|publisher=Springer Berlin Heidelberg|isbn=978-3-642-02838-0|editor-last=Laslier|editor-first=Jean-François|series=Studies in Choice and Welfare|location=Berlin, Heidelberg|pages=2|language=en|doi=10.1007/978-3-642-02839-7|quote=By eliminating the squeezing effect, Approval Voting would encourage the election of consensual candidates. The squeezing effect is typically observed in multiparty elections with a runoff. The runoff tends to prevent extremist candidates from winning, but a centrist candidate who would win any pairwise runoff (the “Condorcet winner”) is also often “squeezed” between the left-wing and the right-wing candidates and so eliminated in the first round.|editor-last2=Sanver|editor-first2=M. Remzi}}</ref><ref name=":4">{{Cite web|url=https://thehill.com/opinion/campaign/3711206-the-flaw-in-ranked-choice-voting-rewarding-extremists/|title=The flaw in ranked-choice voting: rewarding extremists|last=Atkinson|first=Nathan|last2=Ganz|first2=Scott C.|date=2022-10-30|website=The Hill|language=en-US|access-date=2023-05-14|quote=However, ranked-choice voting makes it more difficult to elect moderate candidates when the electorate is polarized. For example, in a three-person race, the moderate candidate may be preferred to each of the more extreme candidates by a majority of voters. However, voters with far-left and far-right views will rank the candidate in second place rather than in first place. Since ranked-choice voting counts only the number of first-choice votes (among the remaining candidates), the moderate candidate would be eliminated in the first round, leaving one of the extreme candidates to be declared the winner.}}</ref>