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{{Short description|Single-winner ranked-choice electoral system}} | |||
] | |||
{{for|the proportional electoral system applying ranked ballots to multi-member constituencies|Single transferable vote}} | |||
{{Electoral systems}} | |||
{{for|ranked methods in general|Ranked voting}} | |||
{{Use dmy dates|date=April 2024}} | |||
{{Use American English|date=May 2024}} | |||
{{Electoral systems sidebar|expanded=Single-winner}} | |||
'''Instant-runoff voting''' ('''IRV'''; {{abbr|]:|United States and Canada|style=font-size:85%}} '''ranked-choice voting''' ('''RCV'''), {{abbr|]:|Australia|style=font-size:85%}} '''preferential voting''', {{abbr|]/]:|United Kingdom and New Zealand|style=font-size:85%}} '''alternative vote''') is a ], ] that uses ] to simulate a series of ]s. In each round, the candidate with the fewest ] (among the remaining candidates) is eliminated. This continues until only one candidate is left. Instant runoff falls under the ] of voting methods,<ref>{{Cite journal |last=Nurmi |first=Hannu |date=June 2005 |title=Aggregation problems in policy evaluation: an overview |url=http://dx.doi.org/10.1016/j.ejpoleco.2004.08.001 |journal=European Journal of Political Economy |volume=21 |issue=2 |pages=287–300 |doi=10.1016/j.ejpoleco.2004.08.001 |issn=0176-2680}}</ref> and is thus closely related to rules like the ].<ref>{{Cite book |last1=Aubin |first1=Jean-Baptiste |url=https://hal.science/hal-04631154/ |title=A simulation-based study of proximity between voting rules |last2=Gannaz |first2=Irène |last3=Leoni-Aubin |first3=Samuela |last4=Rolland |first4=Antoine |date=July 2024}}</ref><ref>{{Cite journal |last1=Hyman |first1=Ross |last2=Otis |first2=Deb |last3=Allen |first3=Seamus |last4=Dennis |first4=Greg |date=2024-09-01 |title=A majority rule philosophy for instant runoff voting |url=https://link.springer.com/article/10.1007/s10602-024-09442-3 |journal=Constitutional Political Economy |language=en |volume=35 |issue=3 |pages=425–436 |doi=10.1007/s10602-024-09442-3 |issn=1572-9966|arxiv=2308.08430 }}</ref> | |||
IRV has found some use ], predominantly in the ]. It is used to elect members of the ] and the ], and to elect the ] in ], ], and ]. | |||
'''Instant-runoff voting''' ('''IRV'''), also known as ''']''', the '''alternative vote''' and '''ranked choice voting''', is a ] used to elect one winner. Voters rank candidates in order of preference, and their ballots are counted as one vote for their first choice candidate. If a candidate secures a majority of votes cast, that candidate wins. Otherwise, the candidate with the fewest votes is eliminated. A new round of counting takes place, with each ballot counted as one vote for the advancing candidate who is ranked highest on that ballot. This process continues until the winning candidate receives a majority of the vote against the remaining candidates. | |||
The rule was first studied by the ], who observed it could eliminate the ] (]).<ref name=":03">{{Cite book |last=Condorcet |first=Jean-Antoine-Nicolas de Caritat |title=Complete Works of Condorcet |date=1788 |volume=13 |publication-date=1804 |pages=243 |language=fr |chapter=On the Constitution and the Functions of Provincial Assemblies |quote=En effet, lorsqu'il y a plus de trois concurrents, le véritable vœu de la pluralité peut être pour un candidat qui n'ait eu aucune des voix dans le premier scrutin. |chapter-url=https://books.google.com/books?id=d0cwAAAAYAAJ&q=Oeuvres%20de%20Condorcet,%20Volume%2013&pg=PA243}}</ref><ref name=":03223">{{Cite journal |last=Nanson |first=E. J. |date=1882 |title=Methods of election: Ware's Method |url=https://archive.org/details/transactionsproc1719roya/page/206 |journal=Transactions and Proceedings of the Royal Society of Victoria |volume=17 |pages=206 |quote=The method was, however, mentioned by Condorcet, but only to be condemned.}}</ref><ref name=":223223">{{cite journal |last1=Campbell |first1=D.E. |last2=Kelly |first2=J.S. |year=2000 |title=A simple characterization of majority rule |journal=] |volume=15 |issue=3 |pages=689–700 |doi=10.1007/s001990050318 |jstor=25055296 |s2cid=122290254}}</ref><ref name=":85223">{{Cite journal |last1=McGann |first1=Anthony J. |last2=Koetzle |first2=William |last3=Grofman |first3=Bernard |date=2002 |title=How an Ideologically Concentrated Minority Can Trump a Dispersed Majority: Nonmedian Voter Results for Plurality, Run-off, and Sequential Elimination Elections |url=https://www.jstor.org/stable/3088418 |journal=American Journal of Political Science |volume=46 |issue=1 |pages=134–147 |doi=10.2307/3088418 |issn=0092-5853 |jstor=3088418 |quote="As with simple plurality elections, it is apparent the outcome will be highly sensitive to the distribution of candidates."}}</ref> Since then, IRV has been criticized for other ] (]), including its ability to eliminate candidates for having ] or ].<ref>{{Cite journal |last1=Doron |first1=Gideon |last2=Kronick |first2=Richard |date=1977 |title=Single Transferrable Vote: An Example of a Perverse Social Choice Function |url=https://www.jstor.org/stable/2110496 |journal=American Journal of Political Science |volume=21 |issue=2 |pages=303–311 |doi=10.2307/2110496 |issn=0092-5853 |jstor=2110496}}</ref> Like ], IRV also exhibits a kind of ] called a ],<ref name=":733">{{Cite journal |last=Nurmi |first=Hannu |date=December 1996 |title=It's not just the lack of monotonicity1 |url=http://www.tandfonline.com/doi/abs/10.1080/00344899608522986 |journal=Representation |language=en |volume=34 |issue=1 |pages=48–52 |doi=10.1080/00344899608522986 |issn=0034-4893}}</ref><ref name=":03244">{{Cite web |last1=Atkinson |first1=Nathan |last2=Ganz |first2=Scott C. |date=2022-10-30 |title=The flaw in ranked-choice voting: rewarding extremists |url=https://thehill.com/opinion/campaign/3711206-the-flaw-in-ranked-choice-voting-rewarding-extremists/ |access-date=2023-05-14 |website=The Hill |language=en-US |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 by a majority of voters to each of the more extreme candidates. 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> which causes it to favor uncompromising alternatives over more-moderate ones.<ref name=":8524">{{Cite journal |last1=McGann |first1=Anthony J. |last2=Koetzle |first2=William |last3=Grofman |first3=Bernard |date=2002 |title=How an Ideologically Concentrated Minority Can Trump a Dispersed Majority: Nonmedian Voter Results for Plurality, Run-off, and Sequential Elimination Elections |url=https://www.jstor.org/stable/3088418 |journal=American Journal of Political Science |volume=46 |issue=1 |pages=134–147 |doi=10.2307/3088418 |issn=0092-5853 |jstor=3088418 |quote="As with simple plurality elections, it is apparent the outcome will be highly sensitive to the distribution of candidates."}}</ref><ref name="Merril 1985224223">{{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 name="Merrill 1984223">{{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=23–48 |doi=10.2307/2110786 |issn=0092-5853 |jstor=2110786 |quote=However, squeezed by surrounding opponents, a centrist candidate may receive few first-place votes and be eliminated under Hare. |via=}}</ref><ref name=":2423">{{Cite journal |last=Robinette |first=Robbie |date=2023-09-01 |title=Implications of strategic position choices by candidates |url=https://doi.org/10.1007/s10602-022-09378-6 |journal=Constitutional Political Economy |language=en |volume=34 |issue=3 |pages=445–457 |doi=10.1007/s10602-022-09378-6 |issn=1572-9966}}</ref> | |||
Instant runoff voting is used to elect members of the ],<ref name="Australian Electoral Commission">http://www.aec.gov.au/</ref> the ], members of ] in India, the ],<ref name="International Constitutional Law">{{cite web|url=http://www.servat.unibe.ch/icl/ei00000_.html|title=Ireland Constitution, Article 12(2.3)|publisher=International Constitutional Law|year=1995|accessdate=15 February 2008}}</ref> the national parliament of ], and the ].<ref name="Fiji Constitution, Section 541">{{cite web|url=http://www.servat.unibe.ch/icl/fj00000_.html|title=Fiji Constitution, Section 54(1)|date=28 July 1998|publisher=International Constitutional Law|accessdate=15 February 2008}}</ref> It is also used in Irish ]s and for electing ]s for the ].<ref name="Notice of House of Lords Conservative Hereditary Peers' By-Election Notice">{{cite web| author = House of Lords | authorlink = House of Lords | url = http://www.parliament.uk/documents/lords-information-office/holnotice20100601.pdf | title = House of Lords Website}}</ref> | |||
Advocates of IRV often argue these properties are positive, as voting rules should encourage candidates to appeal to their ] or political base rather than a broad coalition.<ref>{{Cite journal |last1=Hyman |first1=Ross |last2=Otis |first2=Deb |last3=Allen |first3=Seamus |last4=Dennis |first4=Greg |date=September 2024 |title=A Majority Rule Philosophy for Instant Runoff Voting |journal=Constitutional Political Economy |volume=35 |issue=3 |pages=425–436 |arxiv=2308.08430 |doi=10.1007/s10602-024-09442-3 |issn=1043-4062}}</ref> They also note that in countries like the ] without ] or ], IRV can prevent ] by eliminating minor-party candidates. Unlike a straight plurality vote, IRV also ] by ]. | |||
IRV is employed by several jurisdictions in the United States, including ]; ];<ref name=mpr20090510/> ];<ref name=or2010> | |||
{{cite web|url=http://oaklandrising.org/campaign/instant-runoff-voting|title=Oakland Rising:Instant Runoff Voting |publisher=oaklandrising.com |year=2010 |accessdate=23 December 2010}}</ref> ]; and ].<ref name=mpr20090510> Minnesota Public Radio, 10 May 2009</ref> | |||
== Election procedure == | |||
It is used to elect the leaders of the ] and the ] in the ] and the leader of the ] in a national primary<ref name="thetyee.ca">{{cite web|last=Zehr |first=Garrett |url=http://thetyee.ca/Blogs/TheHook/Federal-Politics/2009/05/02/Liberals-one-member-one-vote/ |title=Liberals adopt one-member, one-vote election system :: The Hook |publisher=Thetyee.ca |date=2 May 2009 |accessdate=6 May 2010}}</ref> and in the elections of city ]s in a number of countries. IRV is used to elect the mayor in cities such as ] in the United Kingdom (in the variant known as ])<ref name="The Supplementary Vote SV">{{cite web|url=http://www.electoral-reform.org.uk/article.php?id=58 |title=Electoral Reform Society - Supplementary Vote |publisher=Electoral-reform.org.uk |date= |accessdate=2011-04-17}}</ref> and ] and ] in New Zealand.<ref name="Elections - 2007 Final Results">{{cite web|url=http://www.wellington.govt.nz/haveyoursay/elections/results/2007/final/mayorfinal.html |title=Elections – 2007 Final Results |year=2007 |publisher=] city council}}</ref> | |||
] | |||
In instant-runoff voting, as with other ] rules, each voter orders candidates from first to last. The counting procedure is then as follows: | |||
# If there is a candidate that has a majority of the top preferences of the valid, active ballots, then that candidate is elected and the count stops. If not, go to step 2. | |||
Many private associations also use IRV,<ref name="Organizations & Corporations">{{cite web|url=http://www.fairvote.org/?page=1964 |title=Organizations & Corporations |publisher=FairVote |date=17 March 2001 |accessdate=6 May 2010}}</ref> including the ]s for science fiction<ref name="Oscars Copy Hugos">{{cite web|url=http://www.thehugoawards.org/2009/09/oscars-copy-hugos/ |title=Oscars Copy Hugos |publisher=The Hugo Awards |date= |accessdate=6 May 2010}}</ref> and the ] in selection of the Oscar for best picture.<ref name="www.oscars.org">{{cite web|url=http://www.oscars.org/press/pressreleases/2009/20090831a.html |title=Preferential Voting Extended to Best Picture on Final Ballot for 2009 Oscars |publisher=Oscars.org |date= |accessdate=6 May 2010}}</ref> | |||
# If there is more than one candidate left, eliminate the one with the fewest top preferences.{{efn|This procedure can be sped-up by eliminating more than one candidate if their combined top preferences are less than the next-lowest remaining candidate; this process is sometimes called batch elimination. When batch elimination is used, the procedure can terminate if some candidate has a majority.}} | |||
It is possible for a candidate to win an instant-runoff race without any support from more than half of voters, even when there is an alternative majority-approved candidate; this occurs when some voters ] to show they do not support any candidates in the final round.<ref name=":1232">{{Cite SSRN |last=Dopp |first=Kathy Anne |date=2011 |title=Realities Mar Instant Runoff Voting Flaws and Benefits of IRV |ssrn=1858374}}</ref> In practice, candidates who do not receive a majority of votes in the first round usually do not finish with a majority.<ref name=":534">{{cite arXiv |eprint=2301.12075 |class=econ.GN |first1=Adam |last1=Graham-Squire |first2=David |last2=McCune |title=An Examination of Ranked Choice Voting in the United States, 2004-2022 |date=2023-03-06}}</ref> | |||
==Terminology== | |||
In the United States, instant-runoff voting is an umbrella term associated with ranked choice elections where multiple rounds of counting determine majority winners; recipients of the fewest votes are eliminated between rounds, and ballots count for the top-ranked candidate not yet eliminated. The term "instant runoff" is used because the method approximates a series of runoff elections tallied in rounds, as in an exhaustive ballot election,<ref name="publications.parliament.uk">{{cite web|url=http://www.publications.parliament.uk/pa/cm200001/cmselect/cmproced/40/4005.htm|title=Second Report: Election of a Speaker|date=15 February 2001|publisher=House of Commons Select Committee on Procedure|accessdate=18 February 2008}}<!--This ref describes similarities/differences between IRV and exhaustive ballot.--></ref> except voters may not change their preference between rounds. | |||
==Properties== | |||
Instant runoff voting has a number of other names, often tied to countries where it is used. In the United States, many observers call it instant runoff voting because it resembles ]. The British usually refer to IRV as the "alternative vote." Although it is only one of several relying on ranking candidates, IRV is referred to as "ranked choice voting" in some American cities and the "preferential ballot" or "preferential voting" in Canada and Australia. It occasionally is referred to as Ware's method after its inventor, American ]. | |||
=== Wasted votes and Condorcet winners === | |||
Compared to a plurality voting system that rewards only the top vote-getter, instant-runoff voting mitigates the problem of ].<ref name="chamberlin23">{{cite journal |last1=Chamberlin |first1=John R. |last2=Cohen |first2=Michael D. |year=1978 |title=Toward Applicable Social Choice Theory: A Comparison of Social Choice Functions under Spatial Model Assumptions |journal=American Political Science Review |publisher=Cambridge University Press (CUP) |volume=72 |issue=4 |pages=1341–1356 |doi=10.2307/1954543 |issn=0003-0554 |jstor=1954543 |quote=A long-established response to the 'wasted vote' problem is the method advocated by Hare...}}</ref> However, it does not ensure the election of a ], which is the candidate who would win a direct election against any other candidate in the race. | |||
===Invalid, incomplete and exhausted ballots{{Anchor|Exhausted ballots}}=== | |||
] law uses "instant runoff" to describe the contingent vote or "batch elimination" form of IRV in one-seat elections. A single second round of counting produces the top two candidates for a runoff election.<ref>{{cite web|url=http://www.ncleg.net/enactedlegislation/sessionlaws/html/2005-2006/sl2006-192.html |title=S.L. 2006-192 |publisher=Ncleg.net |date= |accessdate=6 May 2010}}</ref> Election officials in ] use "instant runoff" to describe a multi-seat election system that attempts to simulate in a single round of voting their previous system of multi-seat runoffs.<ref>{{cite web|url=http://blogs.citizen-times.com/blogs/index.php?blog=10&title=no_instant_runoff_in_hendersonville&more=1&c=1&tb=1&pb=1 |title=CITIZEN-TIMES: Capital Letters – Post details: No instant runoff in Hendersonville |publisher=Blogs.citizen-times.com |date= |accessdate=6 May 2010}}</ref> State law in ]<ref>{{dead link|date=April 2011}}</ref> and ]<ref>{{Dead link|date=May 2010}}</ref> use "instant runoff" to describe the practice of having certain categories of absentee voters cast ranked ballots before the first round of a runoff that are then counted in a runoff election. | |||
All forms of ranked-choice voting reduce to plurality when all ballots rank only one candidate. By extension, ballots for which all candidates ranked are eliminated are equivalent to votes for any non-winner in plurality, and considered ]. | |||
Some political scientists have found the system contributes to higher rates of ],<ref name=":433">{{Cite SSRN |last1=Pettigrew |first1=Stephen |last2=Radley |first2=Dylan |date=2023 |title=Ballot Marking Errors in Ranked-Choice Voting |ssrn=4670677}}</ref> partly because the ballot marking is more complex.<ref name=":433" /><ref name=":534"/> Most jurisdictions with IRV do not require complete rankings and may use columns to indicate preference instead of numbers. In American elections with IRV, more than 99 percent of voters typically cast a valid ballot.<ref>{{cite web |date=1 August 2008 |title=Instant Runoff Voting and Its Impact on Racial Minorities |url=http://politicalreform.newamerica.net/files/irvracememo.pdf |archive-url=https://web.archive.org/web/20110615181347/http://politicalreform.newamerica.net/files/irvracememo.pdf |archive-date=15 June 2011 |access-date=15 August 2011 |publisher=New America Foundation}}</ref> | |||
When the ] (STV) system is applied to a single-winner election it becomes IRV. For this reason IRV is sometimes considered to be merely a limited form of STV. However, IRV is usually excluded from discussions of STV, because STV was designed for multi-seat ], redistributes votes from both the top (winners) and bottom (dropped candidates), and produces broadly proportional results (depending on the number of seats per constituency); none of which need apply to IRV. Even so, some Irish observers mistakenly call IRV "proportional representation" based on the fact that the same ballot form is used to elect its president by IRV and parliamentary seats by STV. | |||
A 2015 study of four local US elections that used IRV found that inactive ballots occurred often enough in each of them that the winner of each election did not receive a majority of votes cast in the first round. The rate of inactive ballots in each election ranged from a low of 9.6 percent to a high of 27.1 percent.<ref>{{cite journal |last1=Burnett |first1=Craig M. |last2=Kogan |first2=Vladimir |date=March 2015 |title=Ballot (and voter) 'exhaustion' under Instant Runoff Voting: An examination of four ranked-choice elections |journal=Electoral Studies |volume=37 |pages=41–49 |doi=10.1016/j.electstud.2014.11.006 |s2cid=11159132}}</ref> | |||
==History== | |||
{{Main|History and use of instant-runoff voting}} | |||
=== Resistance to strategy === | |||
Instant runoff voting was devised in 1871 by American ] ],<ref>{{cite web|author=Wellfire Interactive |url=http://www.fairvote.org/articles/reilly.pdf |title=Articles |publisher=FairVote.org |date= |accessdate=2011-04-17}}</ref> although it is, in effect, a special case of the ] system, which emerged independently in the 1850s. Unlike the single transferable vote in multi-seat elections, however, the only ballot transfers are from backers of candidates who have been eliminated. | |||
Instant-runoff voting has notably high resistance to ] but less to ]. | |||
==== Party strategizing and strategic nomination ==== | |||
The first known use of an IRV-like system in a governmental election was in 1893 in an election for the ] government of ], in Australia.<ref>{{cite web|url=http://www.nuffield.ox.ac.uk/Politics/papers/2002/w23/mclean.pdf|format=PDF|title=Australian electoral reform and two concepts of representation|author=McLean, Iain|date=2002-10|accessdate=22 February 2008|page=11}}</ref> The variant used for this election was a "contingent vote". IRV in its true form was first used in 1908 in a State election in ]. | |||
In Australia, preference deals (where one party's voters agree to place another party's voters second, in return for their doing the same) between parties are common. Parties and candidates often encourage their supporters to participate in these preference deals using ] explaining how to use their lower rankings to maximize the chances of their ballot helping to elect someone in the preference deal before it may exhaust.<ref>{{cite web |date=20 May 2022 |title=Explained: What are 'preference deals' and how do they influence my vote? |url=https://www.9news.com.au/national/explainer-preference-deals-and-how-australias-voting-system-works/7078d92b-d6a6-4b37-919a-3aad0a13e873 |website=]}}</ref> | |||
Instant runoff may be manipulable via strategic candidate entry and exit, reducing similar candidates' chances of winning. Such manipulation does not need to be intentional, instead acting to deter candidates from running in the first place.<ref name="d138">{{cite journal | last=Robinette | first=Robbie | title=Implications of strategic position choices by candidates | journal=Constitutional Political Economy | publisher=Springer Science and Business Media LLC | volume=34 | issue=3 | date=2023-02-02 | issn=1043-4062 | doi=10.1007/s10602-022-09378-6 | doi-access=free | pages=445–457}}</ref> Spatial model simulations indicate that instant runoff rewards strategic withdrawal by candidates.<ref name="Armytage 2014">{{cite journal | first=James|last=Green-Armytage | title=Strategic voting and nomination | journal=Social Choice and Welfare | publisher=Springer | volume=42 | issue=1 | year=2014 | issn=0176-1714 | jstor=43663746 | pages=111–138 | doi=10.1007/s00355-013-0725-3 | s2cid=253847024 | url=http://www.jstor.org/stable/43663746 | access-date=2024-02-23}}</ref>{{efn| name="ExitIncentive"|Figure 4 on page 137 shows instant-runoff voting having exit incentive despite being clone independent.}} | |||
IRV was introduced nationally in Australia in 1918 after the ], in response to the rise of the conservative ], representing small farmers. The Country Party split the anti-Labor vote in conservative country areas, allowing Labor candidates to win on a minority vote. The conservative government of ] introduced preferential voting as a means of allowing competition between the two conservative parties without putting seats at risk. It was first used at the ] by-election on 14 December 1918.<ref>{{cite web|url=http://australianpolitics.com/elections/features/voting-methods-history.shtml |title=Australian Electoral History: Voting Methods |publisher=Australianpolitics.com |date= |accessdate=2011-04-17}}</ref> ] and ] had previously introduced it in the ]. | |||
==== Tactical voting ==== | |||
==Election procedure== | |||
{{See also|Tactical voting#Instant runoff voting}} | |||
===Process=== | |||
] demonstrates that no (deterministic, non-dictatorial) voting method can be entirely immune from tactical voting. This implies that IRV is susceptible to tactical voting in some circumstances. In particular, when there exists a ] who IRV fails to elect, voters who prefer the Condorcet winner to the IRV winner have an incentive to use the ] strategy.<ref name="Armytage 2014" />{{rp|at=proposition 17}} IRV is also sometimes vulnerable to a paradoxical strategy of ranking a candidate higher to make them lose, due to IRV failing the ].<ref>{{cite web |title=Monotonicity and IRV – Why the Monotonicity Criterion is of Little Import |url=http://archive.fairvote.org/?page=2261 |access-date=17 April 2011 |website=archive.fairvote.org}}</ref> | |||
] | |||
Research suggests that IRV is very resistant to tactical voting. In a test of multiple methods, instant runoff was found to be the second-most-resistant to tactical voting, after a class of instant runoff-] hybrids.<ref name=":0">{{Cite journal |journal=] |title=Four Condorcet-Hare Hybrid Methods for Single-Winner Elections |url=https://www.votingmatters.org.uk/ISSUE29/I29P1.pdf |year=2011 |access-date=2024-10-25|first=James|last=Green-Armytage}}</ref> IRV is also completely immune to the ''burying'' strategy: ranking a strong opposition candidate lower can't get one's preferred candidate elected.<ref name="Armytage 2014" />{{rp|at=proposition 3}} | |||
In instant runoff voting, as with other ranked election methods, each voter ranks the list of candidates in order of preference. Under a common ] layout, the voter marks a '1' beside the most preferred candidate, a '2' beside the second-most preferred, and so forth, in ].{{Clarify|date=March 2011}} | |||
Tactical voting in IRV seeks to alter the order of eliminations in early rounds, to ensure that the original winner is challenged by a stronger opponent in the final round. For example, in a three-party election where voters for both the ] and ] prefer the ] candidate to stop the opposing candidate from winning, those voters who care more about defeating the opposition than electing their own candidate may cast a tactical first-preference vote for the centrist candidate. | |||
The mechanics of the process are the same regardless of how many candidates the voter ranks, and how many are left unranked. In some implementations, the voter ranks as many or as few choices as they wish, while in other implementations the voter is ''required'' to rank either all candidates, or a prescribed number of them. | |||
==== Spoiler effect ==== | |||
] IRV ballot]] | |||
{{main|Spoiler effect}} | |||
Proponents of IRV claim that IRV eliminates the spoiler effect, since IRV makes it safe to vote honestly for marginal parties. Under a plurality method, voters who sympathize most strongly with a marginal candidate are strongly encouraged to instead vote for a more popular candidate who shares some of the same principles, since that candidate has a much greater chance of being elected and a vote for the marginal candidate will not result in the marginal candidate's election. An IRV method reduces this problem, since the voter can rank the marginal candidate first and the mainstream candidate second; in the likely event that the fringe candidate is eliminated, the vote is not wasted but is transferred to the second preference. | |||
However, when the third-party candidate is more competitive, they can still act as a spoiler under IRV,<ref name=":043">{{Cite book |last=Borgers |first=Christoph |url=https://books.google.com/books?id=u_XMHD4shnQC |title=Mathematics of Social Choice: Voting, Compensation, and Division |publisher=SIAM |year=2010 |isbn=9780898716955 |quote=Candidates C and D spoiled the election for B ... With them in the running, A won, whereas without them in the running, B would have won. ... Instant runoff voting ... does ''not'' do away with the spoiler problem entirely, although it ... makes it less likely}}</ref><ref name=":723">{{Cite book |last=Poundstone |first=William |url=https://books.google.com/books?id=_24bJHyBV6sC |title=Gaming the Vote: Why Elections Aren't Fair (and What We Can Do About It) |publisher=Farrar, Straus and Giroux |year=2009 |isbn=9781429957649 |quote=IRV is excellent for preventing classic spoilers-minor candidates who irrationally tip the election from one major candidate to another. It is not so good when the 'spoiler' has a real chance of winning}}</ref><ref name="Burlington23">{{cite journal |author=Bristow-Johnson, R. |year=2023 |title=The failure of Instant Runoff to accomplish the purpose for which it was adopted: a case study from Burlington Vermont |url=https://doi.org/10.1007/s10602-023-09393-1 |format=PDF |journal=Const Polit Econ |volume=34 |issue=3 |pages=378–389 |doi=10.1007/s10602-023-09393-1 |s2cid=255657135 |access-date=9 January 2024}}</ref> by taking away first-choice votes from the more mainstream candidate until that candidate is eliminated, and then that candidate's second-choice votes helping a more-disliked candidate to win. In these scenarios, it would have been better for the third party voters if their candidate had not run at all (spoiler effect), or if they had voted dishonestly, ranking their favourite second rather than first (favorite betrayal).<ref>{{Cite SSRN |last=O'Neill |first=Jeffrey C. |date=2006 |title=Everything That Can be Counted Does Not Necessarily Count: The Right to Vote and the Choice of a Voting System |page=340 |ssrn=883058 |quote=With instant runoff voting ... The strategy for the liberal voter is the same as for plurality voting: Her favorite candidate cannot win, so she casts her vote for her favorite candidate with a realistic chance of winning}}</ref>{{Better source needed|reason=The current source is insufficiently reliable (]).|date=September 2024}} This is the same bracketing effect exploited by Robinette and Tideman in their research on strategic campaigning, where a candidate alters their campaign to cause a change in voter honest choice, resulting in the elimination of a candidate who nevertheless remains more preferred by voters. | |||
In the initial count, the first preference of each voter is counted and used to order the candidates. Each first preference counts as one vote for the appropriate candidate. Once all the first preferences are counted, if one candidate holds a ], that candidate wins. Otherwise the candidate who holds the fewest first preferences is eliminated. If there is an exact tie for last place in numbers of votes, ] determine which candidate to eliminate. Some jurisdictions eliminate all low-ranking candidates simultaneously whose combined number of votes is fewer than the number of votes received by the lowest remaining candidates. | |||
For example, in the ], if the Republican candidate who lost in the final instant runoff had not run, the Democratic candidate would have defeated the winning Progressive candidate. In that sense, the Republican candidate was a spoiler—albeit for an opposing Democrat, rather than some political ally—even though leading in first choice support.<ref name="Burlington23" /> This also occurred in the ]. If Republican ], who lost in the final instant runoff, had not run, the more centrist Republican candidate, Nick Begich, would have defeated the winning Democratic candidate, ].<ref>{{cite arXiv |eprint=2209.04764v1 |class=econ.GN |first1=Adam |last1=Graham-Squire |first2=David |last2=McCune |title=A Mathematical Analysis of the 2022 Alaska Special Election for US House |date=2022}}</ref> | |||
Ballots assigned to eliminated candidates are recounted and assigned to one of the remaining candidates based on the next preference on each ballot. The process repeats until one candidate achieves a majority of votes cast for continuing candidates. Ballots that | |||
'exhaust' all their preferences (all its ranked candidates are eliminated) are set aside. | |||
== |
== Reception == | ||
The system has had a mixed reception among ] and ].<ref name=":3">{{cite news |last1=Drutman |first1=Lee |last2=Strano |first2=Maresa |date=10 November 2021 |title=What We Know About Ranked-Choice Voting |url=https://www.newamerica.org/political-reform/reports/what-we-know-about-ranked-choice-voting/conclusion/ |access-date=28 February 2023 |publisher=New America}}</ref><ref name="auto2">{{Cite web |last=Drutman |first=Lee |date=2023-09-18 |title=How I updated my views on ranked choice voting |url=https://leedrutman.substack.com/p/how-i-updated-my-views-on-ranked |access-date=2024-09-02 |website=Undercurrent Events}}</ref> Some have suggested that the system does not do much to decrease the impact of ] relative to plurality.<ref name=":23">{{Cite web |date=10 April 2017 |title=Understanding the Limited Preferential Voting system – EMTV Online |url=https://emtv.com.pg/understanding-the-limited-preferential-voting-system/ |access-date=18 February 2021}}</ref><ref name=":433" /><ref name=":035">{{Cite journal |last1=Endersby |first1=James W. |last2=Towle |first2=Michael J. |date=2014-03-01 |title=Making wasted votes count: Turnout, transfers, and preferential voting in practice |url=https://www.sciencedirect.com/science/article/abs/pii/S0261379413000930 |journal=Electoral Studies |volume=33 |pages=144–152 |doi=10.1016/j.electstud.2013.07.001 |issn=0261-3794}}</ref> Research has found IRV causes lower confidence in elections<ref name="auto1">{{Cite web |title=The Effect of Ranked-Choice Voting in Maine {{!}} MIT Election Lab |url=https://electionlab.mit.edu/articles/effect-ranked-choice-voting-maine |access-date=2024-09-02 |website=electionlab.mit.edu}}</ref><ref name=":06">{{Cite journal |last1=Cerrone |first1=Joseph |last2=McClintock |first2=Cynthia |date=August 2023 |title=Come-from-behind victories under ranked-choice voting and runoff: The impact on voter satisfaction |url=https://onlinelibrary.wiley.com/doi/10.1111/polp.12544 |journal=Politics & Policy |language=en |volume=51 |issue=4 |pages=569–587 |doi=10.1111/polp.12544 |issn=1555-5623}}</ref><ref name="auto3">{{Cite journal |last=Nielson |first=Lindsay |date=August 2017 |title=Ranked Choice Voting and Attitudes toward Democracy in the United States: Results from a Survey Experiment |url=https://onlinelibrary.wiley.com/doi/10.1111/polp.12212 |journal=Politics & Policy |language=en |volume=45 |issue=4 |pages=535–570 |doi=10.1111/polp.12212 |issn=1555-5623}}</ref> and does not substantially affect minority representation,<ref name=":623">{{Cite web |title=The Short-Term Impact of Ranked-Choice Voting on Candidate Entry and Descriptive Representation |url=https://www.newamerica.org/political-reform/reports/rcv-impact-on-candidate-entry-and-representation/ |access-date=2024-09-02 |website=New America |language=en}}</ref> ],<ref name=":3" /><ref name=":035" /> or long-run ].<ref name=":3" /><ref name=":623" /> Opponents have also noted a high rate of repeals for the system.<ref name=":06"/> | |||
As seen above, voters in an IRV election rank candidates on a ]. IRV systems in use in different countries vary both as to ballot design and as to whether or not voters are obliged to provide a full list of preferences. In elections such as those for the President of Ireland and the ], voters are permitted to rank as many (or as few) candidates as they wish. This is known in Australia as '''optional preferential voting'''. | |||
=== Voter confusion and legitimacy === | |||
Under optional preferential voting, voters may make only a first choice, known as "]". Allowing voters to rank only as many candidates as they wish may better reflect their preferences, but may result in ] (where all the voters preferences are eliminated before a candidate is elected). | |||
Governor ]<ref>{{cite web |last=Leary |first=Mal |date=12 June 2018 |title=Opposed To Ranked-Choice Voting, LePage Says He Might Not Certify Primary Election Results |url=http://www.mainepublic.org/post/opposed-ranked-choice-voting-lepage-says-he-might-not-certify-primary-election-results |access-date=14 January 2019 |website=Maine Public}}</ref> and Representative Bruce Poliquin<ref>{{Cite Pacer|plaintiff=Baber|defendant=Dunlap|title=Complaint|doc-number=1|date=13 November 2018|recap-number=8169811|case-state=ME|case-division=1|case-year=18|case-type=cv|case-sequence=00465|access-date=13 January 2019}}</ref> claimed, ahead of the 2018 primary elections, that IRV would result in "one person, five votes", as opposed to "]". Federal judge Lance Walker rejected these claims, and the 1st circuit court denied Poliquin's emergency appeal.<ref>{{cite news |date=22 December 2018 |title=1st Circuit ends Poliquin's efforts to keep House seat |url=https://bangordailynews.com/2018/12/21/politics/1st-circuit-ends-poliquins-efforts-to-keep-house-seat/ |access-date=17 August 2019 |website=Bangor Daily News}}</ref> | |||
=== Similarity to plurality === | |||
One IRV variant requires voters to express an order of preference for every candidate and thus they consider ballots that do not contain a complete ordering of all candidates to be ]. In Australia this variant is known as 'full preferential voting'.<ref>{{cite web|url=http://www.eca.gov.au/systems/single/by_category/preferential.htm|title=Electoral Systems|publisher=Electoral Council of Australia|accessdate=15 February 2008}}</ref> This can become burdensome in elections with many candidates and can lead to ']' in which the voter simply chooses candidates at random or in top-to-bottom order. ] and ]]. | |||
Often instant-runoff voting elections are won by the candidate who leads in first-count vote tallies so they choose the same winner as ] would have. In Australia federal elections, the ] had the largest number of winners who would not have won under first past the post but still only 14 out of 125 seats filled were not won by the first-count leader.<ref>{{Cite web |last=Green |first=Antony |date=11 May 2010 |title=Preferential Voting in Australia |url=https://www.abc.net.au/news/2010-05-12/preferential-voting-in-australia/9389472 |access-date=1 November 2020 |website=www.abc.net.au}}</ref> | |||
=== Participation === | |||
===Candidate order on the ballot paper=== | |||
The common way to list candidates on a ballot paper is alphabetically or by random lot. In some cases candidates may also be grouped by political party. Alternatively, ] involves randomly changing candidate order for each print run. | |||
The effect of IRV on voter turnout is difficult to assess. In a 2021 report, researchers at ], a ] based in Washington, D. C., said it may increase turnout by attracting more and more diverse candidates, but the impact would be realized most significantly by getting rid of the need for primaries.<ref name="auto12">{{Cite web |title=What We Know About Ranked-Choice Voting |url=http://newamerica.org/political-reform/reports/what-we-know-about-ranked-choice-voting/ |website=New America}}</ref> The overall impact on diversity of candidates is difficult to detect.<ref name=":3"/> | |||
===Party strategies=== | |||
Where preferential voting is used for the election of an assembly or council, parties and candidates often advise their supporters on their lower preferences, especially in Australia where a voter must rank all candidates to cast a valid ballot. This can lead to "preference deals", a form of pre-election bargaining, in which smaller parties agree to direct their voters in return for support from the winning party on issues critical to the small party.{{citation needed|date=November 2010}} However, this relies on the assumption that supporters of a minor party will mark preferences for another party based on the advice that they have been given. | |||
==Terminology== | |||
===Counting logistics=== | |||
While instant run-off voting is distinguished from its multiple winner equivalent, the ], in most English-speaking discussion of electoral systems, no distinction between the two is made in ], one of the few countries to use these systems in all elections, either by the general population or in legal texts. The ] describes the electoral system as "proportional representation by means of the single transferable vote"<ref>ref name="Articles 16.2.5°, 12.2.3°, and 18.5, Constitution of Ireland">{{cite web |date=January 2020 |title=Constitution of Ireland (English) |url=https://www.irishstatutebook.ie/eli/cons/en/html |access-date=19 December 2024 |publisher=Office of the Attourney General}}</ref>, as do all other statutory authorities, when referring to either single-winner or multiple-winner elections. The acronym "PR-STV" is in general use to describe both types of elections. Examples of single-winner elections in Ireland which are described officially as "proportional representation by means of the single transferable vote" are the ] and the ] (chairperson of ]). The lack of distinction between the systems in Ireland reflects that there is no difference in the mechanics of the process from election to election, only the number of candidates to be elected by that process. This is not always the case when discussing the systems in the abstract, as there are many variations in how such elections could be run. | |||
Most IRV elections historically have been tallied by hand, including in elections to ]'s House of Representatives. In the modern era, voting equipment can be used to administer the count either partially or fully. | |||
Instant-runoff voting derives its name from the way the ballot count simulates a series of runoffs, similar to an ], except that voters do not need to turn out several times to vote.<ref name="publications.parliament.uk2">{{cite web |date=15 February 2001 |title=Second Report: Election of a Speaker |url=https://publications.parliament.uk/pa/cm200001/cmselect/cmproced/40/4005.htm |access-date=18 February 2008 |publisher=House of Commons Select Committee on Procedure}}<!--This ref describes similarities/differences between IRV and exhaustive ballot.--></ref> It is also known as the alternative vote, transferable vote, ranked-choice voting (RCV), single-seat ranked-choice voting, or preferential voting (but use of some of those terms may lead to misunderstanding as they also apply to STV.)<ref>{{Cite journal |last=Cary |first=David |date=1 January 2011 |title=Estimating the Margin of Victory for Instant-runoff Voting |url=http://dl.acm.org/citation.cfm?id=2028012.2028015 |journal=Proceedings of the 2011 Conference on Electronic Voting Technology/Workshop on Trustworthy Elections |series=EVT/WOTE'11 |pages=3}}</ref> | |||
In Australia, election officials almost always conduct a first preference count (and sometimes a two candidate preference allocation) under the scrutiny of the candidates or their appointed scrutineers at individual polling booths immediately after polling closes.<ref>http://blogs.abc.net.au/antonygreen/2011/02/how-the-alternative-vote-works.html</ref> That count is communicated to the electorate returning officer at a central location on the night and the actual ballot papers are secured and subsequently delivered to that official. These ballots are then checked, and a final count of these ballots plus any absentee and special category ballots happens again under the scrutiny of the candidates at premises that have been set up for the purpose by the returning officer. This process may take several days but the outcome of the election is usually known well before all ballots have been counted and preferences allocated. | |||
Britons and New Zealanders generally call IRV the "alternative vote" (AV).<ref>{{cite web |date=8 February 2012 |title=BBC News – Alternative vote |url=https://www.bbc.com/news/uk-politics-12910547 |access-date=9 October 2019 |website=bbc.com |publisher=British Broadcasting Corporation}}</ref><ref>{{cite web |date=30 September 2017 |title=Opinion: OUSA Needs the Alternative Vote |url=https://www.critic.co.nz/news/article/7194/opinion-ousa-needs-the-alternative-vote |access-date=9 October 2019 |website=Critic – Te Arohi |publisher=Otago University Students' Association |location=Otago, New Zealand}}</ref> Australians, who use IRV for most single winner elections, call IRV "preferential voting".<ref>{{cite news |date=11 December 2020 |title=Liberal plan to change federal voting laws may have crossbench support |url=https://www.theguardian.com/australia-news/2020/dec/12/liberal-plan-to-change-federal-voting-laws-may-have-crossbench-support |access-date=13 February 2021 |work=The Guardian}}</ref> While this term is widely used by Australians, it is somewhat of a ]. Depending on how "preferential" is defined, the term would include all voting systems, apply to any system that uses ranked ballots (thus both IRV and STV), or would exclude IRV (IRV fails ] because ballot markings are not interpreted as "preferences" in the traditional sense. Under IRV (and STV), secondary preferences are used as back-up preferences/contingency votes). | |||
Ireland in its presidential elections has several dozen counting centers around the nation. Each center reports its totals and receives instructions from the central office about which candidate or candidates to eliminate in the next round of counting based on which candidate is in last place. The count typically is completed the day after the election, as in 1997.<ref>http://archive.fairvote.org/sf/SFLawsuit_Richie.pdf</ref>. | |||
Jurisdictions in the United States such as ], ], ], and ] have tended to use the term "ranked-choice voting" in their laws that apply to IRV contests. The San Francisco Department of Elections claimed the word "instant" in the term "instant-runoff voting" could confuse voters into expecting results to be immediately available.<ref>Appendix D, Instant Runoff Voting, San Francisco Charter § 13.102 https://sfgov.org/ccsfgsa/sites/default/files/Voting%20Systems%20Task%20Force/AppendixD__.pdf.</ref><ref>{{cite web |last=Arntz |first=John |date=2 February 2005 |title=Ranked-Choice Voting: A Guide for Candidates |url=http://www.fairvote.org/media/irv/sanfrancisco/RCVCandidateGuide04.pdf |archive-url=https://web.archive.org/web/20081202040611/http://fairvote.org/media/irv/sanfrancisco/RCVCandidateGuide04.pdf |archive-date=2 December 2008 |access-date=25 August 2009 |publisher=Department of Elections: City and County of San Francisco |via=] |quote=In San Francisco, ranked-choice voting is sometimes called 'instant run-off voting.' The Department of Elections generally uses the term ranked-choice voting, because it describes the voting method—voters are directed to rank their first-, second- and third-choice candidates. The Department also uses the term ranked-choice voting because the word 'instant' might create an expectation that final results will be available immediately after the polls close on election night.}}</ref> As a result of American influence, the term ranked-choice voting is often used in Canada as well.<ref name="auto">{{cite web |title=What is Ranked Choice Voting? |url=http://www.london.ca/city-hall/elections/ranked-choice-voting/Pages/What-is-Ranked-Choice-Voting.aspx |archive-url=https://web.archive.org/web/20180226101409/http://www.london.ca/city-hall/elections/ranked-choice-voting/Pages/What-is-Ranked-Choice-Voting.aspx |archive-date=26 February 2018 |website=City of London}}</ref> American NGO ] has promoted the terminology "ranked-choice voting" to refer to IRV,<ref name="auto" /><ref>{{cite web |date=17 August 2019 |title=How RCV Works |url=https://www.fairvote.org/rcv#how_rcv_works |access-date=17 August 2018 |website=FairVote}}</ref> a choice that has caused controversy and accusations that the organization is attempting to obscure the existence of other ] methods that could compete with IRV.{{Cn|date=May 2024}} | |||
In the United States, California cities such as ] and ] administer IRV elections on voting machine, with optical scanning machines recording preferences and software tallying the IRV algorithm.<ref>http://www.fairvote.org/ranked-voting-and-election-integrity-3</ref> ]'s pilot program in 2007 tallied first choices on optical scan equipment at the polls and then used a central hand-count for the IRV tally.<ref>archive.fairvote.org/?page=2543</ref> ] in 2011 will use its usual voting machines to tally first choice at the polls, then a central scan with different equipment if an IRV tally is necessary. <ref>http://www.mpbn.net/Home/tabid/36/ctl/ViewItem/mid/3478/ItemId/17382/Default.aspx</ref> | |||
IRV is occasionally referred to as Hare's method<ref>{{Cite encyclopedia |title=Voting Methods |encyclopedia=The Stanford Encyclopedia of Philosophy |url=https://plato.stanford.edu/archives/fall2019/entries/voting-methods/ |last=Pacuit |first=Eric |date=24 June 2019 |orig-date=3 August 2011 |editor1-last=Zalta |editor1-first=Edward N. |edition=Fall 2019 |via=plato.stanford.edu}}</ref> (after ]) to differentiate it from other ranked-choice voting methods such as ], ], and ], which use weighted preferences or methods that allow voter's lower preference to be used against voter's most-preferred choice. | |||
==Examples== | |||
Some examples of IRV elections are given below. | |||
When the ] (STV) method is applied to a single-winner election, it becomes IRV; the government of Ireland has called IRV "proportional representation" based on the fact that the same ballot form is used to elect its president by IRV and parliamentary seats by proportional representation (STV), but IRV is a non-proportional winner-take-all (single-winner) election method, while STV elects multiple winners.<ref>{{cite web |title=Proportional Representation |url=https://www.citizensinformation.ie/en/government_in_ireland/elections_and_referenda/voting/proportional_representation.html |access-date=17 August 2019 |publisher=Citizens Information Board}}</ref> | |||
===2006 Burlington mayoral election=== | |||
{{See also|Instant-runoff voting in the United States#Burlington_results_2006}} | |||
{| class="wikitable" style="text-align:center; float:right; margin-left:1em" | |||
|- | |||
!Candidate | |||
!colspan=2|Round 1 | |||
!colspan=2|Round 2 | |||
|- | |||
!] | |||
| 3,809 || ''(38.9%)'' | |||
| 4,761 || ''(48.6%)'' | |||
|- | |||
!] | |||
| 3,106||''(31.7%)'' | |||
| 3,986||''(40.7%)'' | |||
|- | |||
!Kevin Curley | |||
| 2,609||''(26.7%)'' | |||
|colspan=2 | — | |||
|- | |||
!Other | |||
|254||''(2.6%)'' | |||
|colspan=2 | — | |||
|- | |||
!Exhausted ballots | |||
|10||''(0.1%)'' | |||
|1,041||''(10.5%)'' | |||
|- | |||
!Total | |||
|9,778||''(100%)'' | |||
|9,778||''(100%)'' | |||
|} | |||
State law in ]<ref>{{cite web |title=South Carolina General Assembly : 116th Session, 2005–2006 |url=http://www.scstatehouse.gov/sess116_2005-2006/bills/3720.doc |access-date=1 March 2015 |website=Scstatehouse.gov}}</ref> and ]<ref>{{cite web |title=Bill Information |url=http://www.arkleg.state.ar.us/assembly/2005/R/Pages/BillInformation.aspx?measureno=HB1770 |access-date=28 January 2015 |website=Arkleg.state.ar.us}}</ref> use "instant runoff" to describe the practice of having certain categories of absentee voters cast ranked-choice ballots before the first round of an election and counting those ballots in any subsequent runoff elections. | |||
In 2006 the U.S. city of ], held a mayoral election using instant runoff voting. Progressive ] won in two rounds with 48.6% of the first round ballots, defeating Democrat ] who achieved 40.7%. 10.6% (1,031) of the ballots were exhausted before the final round, because those voters (largely backers of Republican candidate Kevin Curley) offered no preference between the final two candidates, Miller and Kiss.<ref>{{cite web|url=http://www.burlingtonvotes.org/20060307/2006%20Burlington%20Mayor%20Round3.htm|title=2006 Burlington mayoral election|date=7 March 2006|publisher=Voting Solutions|accessdate=22 February 2008}}</ref> | |||
==History and use== | |||
After the first round, all but two candidates were eliminated, as their combined vote total (2,863) was less than Miller's, so that none could pull ahead of Miller, even by receiving every vote from the other minor candidates. The votes for these candidates were recounted and redistributed between Kiss and Miller. After the second round count, Kiss was declared the winner as he had obtained a majority (54.4%) of the remaining unexhausted ballots. | |||
{{Main|History and use of instant-runoff voting}} | |||
{{-}} | |||
=== History === | |||
===1990 Irish presidential election=== | |||
This method was first discussed by the ] in 1788, who quickly rejected it after showing it would often eliminate a candidate preferred by a majority of voters.<ref name=":032">{{Cite journal |last=Nanson |first=E. J. |date=1882 |title=Methods of election: Ware's Method |url=https://archive.org/details/transactionsproc1719roya/page/206 |journal=Transactions and Proceedings of the Royal Society of Victoria |volume=17 |pages=206 |quote=The method was, however, mentioned by Condorcet, but only to be condemned.}}</ref><ref>{{Cite book |last=Condorcet |first=Jean-Antoine-Nicolas de Caritat |chapter-url=https://books.google.com/books?id=d0cwAAAAYAAJ&q=Oeuvres%20de%20Condorcet,%20Volume%2013&pg=PA243 |chapter=On the Constitution and the Functions of Provincial Assemblies |date=1788 |title=Complete Works of Condorcet |volume=13 |publication-date=1804 |pages=243 |language=fr |quote=En effet, lorsqu'il y a plus de trois concurrents, le véritable vœu de la pluralité peut être pour un candidat qui n'ait eu aucune des voix dans le premier scrutin.}}</ref> | |||
{{See also|Irish presidential election, 1990}} | |||
{|class="wikitable" style="float:right; text-align:center; margin:10px" | |||
IRV was later independently reinvented by ] (of England) and Carl Andrae (of Denmark) in the form of the ]. ] then proposed applying the system to single-winner contests. (He also invented the ], which equates to a simple majority in a single-winner contest.) | |||
=== Global use === | |||
{{main|History and use of instant-runoff voting#Use by country}} | |||
==== National level elections ==== | |||
{| class="wikitable" | |||
! width=150| Country | |||
! width=150| Body or office | |||
! width=180| Type of body or office | |||
! scope="col" | ] | |||
! scope="col" | Total seats | |||
! scope="col" | Notes | |||
|- | |- | ||
! scope="row" | Australia | |||
! colspan=5|Irish presidential election, 1990<ref> | |||
|] | |||
{{cite web | |||
|Lower chamber of legislature | |||
|url=http://www.electionsireland.org/result.cfm?election=1990P&cons=194 | |||
|IRV | |||
|title=Presidential Election November 1990 | |||
|151 | |||
|work=ElectionsIreland.org | |||
| | |||
|accessdate=23 November 2009 | |||
}}</ref> | |||
|- | |- | ||
! rowspan="2" scope="row" | Ireland | |||
!Candidate | |||
|] | |||
!colspan=2|Round 1 | |||
|Head of State | |||
!colspan=2|Round 2 | |||
|IRV | |||
| | |||
| | |||
|- | |- | ||
|] | |||
|Lower chamber of legislature | |||
|612,265 || ''(38.9%)'' | |||
|] (STV), by-elections using IRV | |||
|817,830 || ''(51.6%)'' | |||
|158<ref name="fn_22">The ] or Speaker of ] is returned automatically for whichever constituency s/he was elected if they wish to seek re-election, reducing the number of seats contested in that constituency by one. (In that case, should the Ceann Comhairle be from a three-seater, only two seats are contested in the general election from there.) As a result, if the Ceann Comhairle wishes to be in the next Dáil, only 165 seats are actually contested in a general election.</ref> | |||
| | |||
|- | |- | ||
! scope="row" | Papua New Guinea | |||
!] | |||
|] | |||
|694,484||''(43.8%)'' | |||
|Unicameral legislature | |||
|731,273||''(46.2%)'' | |||
|IRV | |||
|109 | |||
| | |||
|- | |- | ||
! rowspan="3" scope="row" | United States | |||
!] | |||
|] (via ]) | |||
|267,902||''(16.9%)'' | |||
|Head of State and Government | |||
|colspan=2 | — | |||
|] and ] use IRV to select the state's electoral college seat winner or winners. In Maine, 2 electors are allocated to the winner of the state vote plurality and the others (currently 2) are allocated by plurality in each congressional district. In Alaska, the winner gets all Electoral College electors of the state (as Alaska has only one ''at-large'' district, the effect is the same). | |||
|7 EVs<ref>electoral votes</ref> (out of 538) | |||
| | |||
|- | |- | ||
|] | |||
!Exhausted ballots | |||
|Lower chamber of legislature | |||
|9,444||''(0.6%)'' | |||
| rowspan="2" |IRV in Maine | |||
|34,992||''(2.2%)'' | |||
Nonpartisan primary system with IRV in the second round (among top four candidates) in Alaska.<ref name="boston.com2">{{cite web |date=10 November 2016 |title=Maine became the first state in the country Tuesday to pass ranked-choice voting |url=https://www.boston.com/news/politics/2016/11/10/maine-became-the-first-state-in-the-country-to-pass-ranked-choice-voting |access-date=10 November 2016}}</ref><ref>{{cite web |title=Ranked Choice Voting {{!}} Maine Voters Rank Candidates |url=http://mainerankedchoice.vote/ |access-date=8 April 2018 |website=Maine Uses Ranked Choice Voting |archive-date=4 April 2018 |archive-url=https://web.archive.org/web/20180404201657/http://mainerankedchoice.vote/ |url-status=dead }}</ref><ref name="Maine20182">{{cite news |last=Russell |first=Eric |date=12 June 2018 |title=Mainers vote to keep ranked-choice voting, with supporters holding commanding lead |url=https://www.pressherald.com/2018/06/12/ranked-choice-voting-takes-lead-in-early-balloting/ |access-date=13 June 2018 |work=Portland Press Herald}}</ref><ref>{{Cite web |title=Alaska Ballot Measure 2, Top-Four Ranked-Choice Voting and Campaign Finance Laws Initiative (2020) |url=https://ballotpedia.org/Alaska_Ballot_Measure_2,_Top-Four_Ranked-Choice_Voting_and_Campaign_Finance_Laws_Initiative_(2020) |access-date=17 November 2020 |website=Ballotpedia}}</ref> | |||
|3 (out of 435) | |||
| | |||
|- | |- | ||
|] | |||
!Total | |||
|Upper chamber of legislature | |||
|1,584,095||''(100%)'' | |||
| |
|4 (out of 100) | ||
| | |||
|} | |} | ||
=== ''Robert's Rules of Order'' === | |||
The result of the ] provides an example of how instant runoff voting can produce a different result than ]. The three candidates were ] of the traditionally dominant ] party, ] of ], and ], nominated by the ] and the ]. After the first round, Lenihan had the largest share of the first choice rankings (and hence would have won a first-past-the-post vote), but no candidate attained the necessary majority. Currie was eliminated and his votes reassigned to the next choice ranked on each ballot; in this process, Robinson received 82% of Currie's votes, thereby overtaking Lenihan.<!-- no cite: since only 3 candidates just simple ratio of extra votes in 2nd count. --> | |||
In the United States, the sequential elimination method used by IRV is described in '']'' as an example of ] that can be used to elect officers.<ref name="autogenerated12">{{cite book |last=Robert |first=Henry |title=Robert's Rules of Order Newly Revised |publisher=Da Capo Press |year=2011 |isbn=978-0-306-82020-5 |edition=11th |pages=425–428}}</ref> ''Robert's Rules'' note that ranked-choice systems (including IRV) are an improvement on ] but recommend against runoff-based rules because they often prevent the emergence of a consensus candidate with broad support. The book instead recommends repeated balloting until some candidate manages to win a majority of votes. Two other books on American parliamentary procedure, '']''<ref>{{cite parl|title=TSC|page=148|edition=4th}}</ref> and '']'',<ref>{{cite parl|title=RID|page=145|edition=1985|year=1985}}</ref> take a similar stance. | |||
{{clr}} | |||
==Similar methods== | |||
==Voting system criteria== | |||
===Runoff voting=== | |||
{{Main|Comparison of instant runoff voting to other voting systems#Voting system criteria}} | |||
{{Original research section|date=August 2024}} | |||
Scholars rate voting systems using mathematically derived ], which describe desirable features of a system. No ranked preference method can meet all of the criteria, because some of them are mutually exclusive, as shown by statements such as ] and the ].<ref>David Austen-Smith and Jeffrey Banks, "Monotonicity in Electoral Systems," ''American Political Science Review'', Vol 85, No 2 (Jun. 1991)</ref> | |||
The term ''instant-runoff voting'' is derived from the name of a class of voting methods called runoff voting. In runoff voting voters do not rank candidates in order of preference on a single ballot. Instead a similar effect is achieved by using multiple rounds of voting. All multi-round runoff voting methods allow voters to change their preferences in each round, incorporating the results of the prior round to influence their decision, which is not possible in IRV. | |||
Many of the mathematical criteria by which voting systems are compared were formulated for voters with ordinal preferences. If voters vote according to a the same ordinal preferences in both rounds, criteria can be applied to ]s of runoffs, and in that case, each of the criteria failed by IRV is also failed by the ] as they relate to automatic elimination of trailing candidates. Partial results exist for other models of voter behavior in the two-round system: see the ] for more information. | |||
The runoff method closest to IRV is the ]. In this method—familiar to fans of the television show '']''—one candidate is eliminated after each round, and many rounds of voting are used, rather than just two. Because holding many rounds of voting on separate days is generally expensive, the exhaustive ballot is not used for large-scale, public elections. | |||
The criteria that IRV meets, and those that it does not, are listed below. | |||
A more practical form of runoff voting is the ], which excludes all but the top-two candidates after the first round, rather than gradually eliminating candidates over a series of rounds. Eliminations can occur with or without allowing and applying preference votes to choose the final two candidates. A second round of voting or counting is only necessary if no candidate receives an overall majority of votes. This method is used in Mali, France and the Finnish and Slovenian presidential election. | |||
===Majority criterion=== | |||
{{Tick}} The ''']''' criterion states that "if one candidate is preferred by an absolute majority of voters, then that candidate must win". IRV meets this criterion. | |||
===Contingent vote=== | |||
===Mutual majority criterion=== | |||
{{Original research section|date=August 2024}} | |||
{{Tick}} The ''']''' criterion states that "if every voter prefers every member of a group of candidates to every candidate not in that group, then one of the preferred group must win". IRV meets this criterion. | |||
] | |||
The ], also known as "top-two IRV", is the same as IRV, except that if no candidate achieves a majority in the first round of counting, all but the two candidates with the most votes are eliminated, and the second preferences for those ballots are counted. As in IRV, there is only one round of voting. | |||
Under a variant of contingent voting used in ], and formerly for the elections for ] in the United Kingdom, voters rank a specified maximum number of candidates. In London, the ] allowed{{efn|Following the ], voting in mayoral elections now takes place under the ] system.}} voters to express first and second preferences only. Sri Lankan voters ]. | |||
===Later-no-harm criterion=== | |||
{{Tick}} The ''']''' criterion states that "if a voter alters the order of candidates lower in his/her preference (e.g. swapping the second and third preferences), then that does not affect the chances of the most preferred candidate being elected". IRV meets this criterion. | |||
While similar to "sequential-elimination" IRV, top-two can produce different results. Excluding more than one candidate after the first count might eliminate a candidate who would have won under sequential elimination IRV. Restricting voters to a maximum number of preferences is more likely to exhaust ballots if voters do not anticipate which candidates will finish in the top two. This can encourage voters to vote more ], by ranking at least one candidate they think is likely to win. | |||
===Resolvability criterion=== | |||
{{Tick}} The ''']''' criterion states that "the probability of an exact tie must diminish as more votes are cast". IRV meets this criterion. | |||
Conversely, a practical benefit of 'contingent voting' is expediency and confidence in the result with only two rounds. | |||
===Condorcet winner criterion=== | |||
{{Cross}} The ''']''' criterion states that "if a candidate would win a ] against every other candidate, then that candidate must win the overall election". IRV does not meet this criterion. | |||
===Larger runoff process=== | |||
IRV is more likely to elect the Condorcet winner than plurality voting and traditional runoff elections. The California cities of Oakland, San Francisco and San Leandro in 2010 provide an example; there were a total of four elections in which the plurality voting leader in first choice rankings was defeated, and in each case the IRV winner was the Condorcet winner, including a San Francisco election in which the IRV winner was in third place in first choice rankings.<ref>{{cite web|author=Wellfire Interactive |url=http://www.fairvote.org/understanding-the-rcv-election-results-d10 |title=Understanding the RCV Election Results in District 10 |publisher=FairVote.org |date= |accessdate=2011-04-17}}</ref> | |||
IRV may also be part of a larger runoff process: | |||
* Some jurisdictions that hold runoff elections allow absentee (only) voters to submit IRV ballots, because the interval between votes is too short for a second round of absentee voting. IRV ballots enable absentee votes to count in the second (general) election round if their first choice does not make the runoff. ], ] and ] adopt this approach.<ref>{{cite web |title=Initiatives – Pew Center on the States |url=http://www.electionline.org/Portals/1/Publications/SC.EAP.2006primary.pdf |archive-url=https://web.archive.org/web/20080516235221/http://www.electionline.org/Portals/1/Publications/SC.EAP.2006primary.pdf |archive-date=16 May 2008 |access-date=6 May 2010 |website=Electionline.org}}</ref> Louisiana uses it only for members of the United States Service or who reside overseas.<ref>{{Citation |title=IRV for Louisiana's Overseas Voters |type=web page |url=http://archive.fairvote.org/?page=1669 |access-date=16 June 2013 |publisher=FairVote IRV America}}</ref>{{Better source needed|reason=The current source is insufficiently reliable (]).|date=September 2024}}{{Update needed|date=September 2024}} | |||
===Condorcet loser criterion=== | |||
* IRV can quickly eliminate weak candidates in early rounds of an ] runoff, using rules to leave the desired number of candidates for further balloting. | |||
{{Tick}} The ''']''' criterion states that "if a candidate would lose a ] against every other candidate, then that candidate must not win the overall election". IRV meets this criterion. | |||
* IRV elections that require a majority of cast ballots but not that voters rank all candidates may require more than a single IRV ballot due to exhausted ballots. | |||
* Robert's Rules recommends ] for elections by mail and requiring a majority of cast votes to elect a winner. For in-person elections, they recommend repeated balloting until one candidate receives an absolute majority of all votes cast; if candidates drop out as soon as it becomes clear they cannot win, this procedure will always elect a ]. The use of repeated balloting allows voters to resolve ] by discussion and compromise, or by electing a consensus candidate who might have polled poorly in the initial election.<ref name="autogenerated12" /> | |||
===Comparison to first-past-the-post=== | |||
===Consistency criterion=== | |||
In the ], 135 out of the 150 ] seats (or 90 percent) were won by the candidate who led on first preferences. The other 15 seats (10 percent) were won by the candidate who placed second on first preferences.<ref>] (8 September 2015). – Antony Green's Election Blog (Australian Broadcasting Corporation). Retrieved 8 September 2015.</ref>{{Better source needed|reason=The current source is insufficiently reliable (]).|date=September 2024}} | |||
{{Cross}} The ''']''' criterion states that if dividing the electorate into two groups and running the same election separately with each group returns the same result for both groups, then the election over the whole electorate should return this result. IRV, like all preferential voting systems which are not ], does not meet this criterion: dividing the electorate into two groups and running the same election separately with each group is not guaranteed to return the same results as the election over the whole electorate. In a general sense, this reflects the fact that the system does not produce as evenly spread a set of winners as a ] process.<ref>http://www.fairvote.ca/files/AV-backgrounder-august2009_1.pdf</ref> | |||
=== |
=== Variations === | ||
]]] | |||
{{Cross}} The ''']''' criterion states that "a voter can't harm a candidate's chances of winning by voting that candidate higher, or help a candidate by voting that candidate lower, while keeping the relative order of all the other candidates equal." IRV does not meet this criterion. Allard<ref>{{cite web|author=Crispin Allard|url=http://www.mcdougall.org.uk/VM/ISSUE5/P1.HTM|title=Estimating the Probability of Monotonicity Failure in a UK General Election|date=1996-01|accessdate=2011-05-04}}</ref> claims failure is unlikely, at a less than 0.03% chance per election. Some critics<ref>{{cite web|author=Warren D. Smith|url=http://rangevoting.org/Monotone.html|title=Monotonicity and Instant Runoff Voting|accessdate=2011-05-04}}</ref> argue in turn that Allard's calculations are wrong and the probability of monotonicity failure is much greater, at 14.5% under the impartial culture election model in the three-candidate case, or 7-10% in the case of a left-right spectrum. Lepelly ''et al.''<ref>Dominique Lepelley, Frederic Chantreuil, Sven Berg: , Mathematical Social Sciences 31 (1996) 133-146</ref> find a 2%-5% probability of monotonicity failure under the same election model as Allard. | |||
A number of IRV methods, varying as to ballot design and as to whether or not voters are obliged to provide a full list of preferences, are in use in different countries and local governments. | |||
In an ] system, voters can give a preference to as many candidates as they wish. They may make only a single choice, known as "]", and some jurisdictions accept a single box marked with an "X" (as opposed to a numeral "1") as valid for the first preference. This may result in exhausted ballots, where all of a voter's preferences are eliminated before a candidate is elected, such that the "majority" in the final round may only constitute a minority fraction of all ballots cast. Optional preferential voting is used for elections for the ] as well as some elections in ] and ].<ref>{{cite web |date=28 January 2020 |title=Voting system |url=https://www.ecq.qld.gov.au/how-to-vote/voting-systems |access-date=17 November 2020 |website=www.ecq.qld.gov.au |publisher=Electoral Commission of Queensland}}</ref><ref>{{cite web |last1=Stevens |first1=Bronwyn |date=27 January 2015 |title=Are Queenslanders in danger of 'wasting' their votes? |url=https://www.theconversation.com/amp/are-queenslanders-in-danger-of-wasting-their-votes-35919 |access-date=28 November 2020 |website=The Conversation}}</ref> | |||
===Participation criterion=== | |||
{{Cross}} The ''']''' criterion states that "the best way to help a candidate win must not be to abstain".<ref>More precisely, submitting a ballot that ranks A ahead of B should never change the winner from A to B.</ref> IRV does not meet this criterion: in some cases, the voter's preferred candidate can be best helped if the voter does not vote at all.<ref name="WDSParticipationReversalSymmetry">{{cite web|author=Warren D. Smith|url=http://rangevoting.org/TBlecture.html#partic|title=Lecture "Mathematics and Democracy"|accessdate=2011-05-12}}</ref> Depankar Ray<ref>{{cite web|author=Depankar Ray|url=http://www.sciencedirect.com/science/article/B6V88-46RVD34-6/2/4ade9a3bc999c9d9f295fea853253435|title=On the practical possibility of a "no show paradox" under the single transferable vote, Mathematical Social Sciences 11,2 (1986) 183-189|accessdate=2011-05-14}}</ref> finds a 50% probability that, when IRV elects a different candidate than Plurality, some voters would have been better off not showing up. | |||
In a large scale election, the issue is academic since the behaviors required of the electors to achieve it do not scale.{{citation needed|date=May 2011}} | |||
In a full-preferential voting method, voters are required to mark a preference for every candidate standing.<ref>{{cite web |title=Electoral Systems |url=http://www.eca.gov.au/systems/single/by_category/preferential.htm |archive-url=https://web.archive.org/web/20080309220219/http://www.eca.gov.au/systems/single/by_category/preferential.htm |archive-date=9 March 2008 |access-date=15 February 2008 |publisher=Electoral Council of Australia}}</ref> Ballots that do not contain a complete ordering of all candidates are in some jurisdictions considered ] or invalid, even if there are only two candidates standing. This can become burdensome in elections with many candidates and can lead to "]", in which some voters simply choose candidates at random or in top-to-bottom order, or a voter may order his or her preferred candidates and then fill in the remainder on a donkey basis. Full preferential voting is used for elections to the ] and for most ]. | |||
===Reversal symmetry criterion=== | |||
{{Cross}} The ''']''' criterion states that "if candidate A is the unique winner, and each voter's individual preferences are inverted, then A must not be elected". IRV does not meet this criterion: it is possible to construct an election where reversing the order of every ballot paper does not alter the final winner<ref name="WDSParticipationReversalSymmetry"/>. However, this is essentially an academic exercise. | |||
Other methods only allow marking preferences for a maximum of the voter's top three favourites, a form of partial preferential voting.<ref>{{cite web |title=Ranked-Choice Voting |url=http://www.acgov.org/rov/rcv/faq.htm |access-date=15 December 2016 |website=Registrar of Voters, Alameda County |quote=This format allows a voter to select a first-choice candidate in the first column, a second-choice candidate in the second column, and a third-choice candidate in the third column.}}</ref> | |||
===Independence of irrelevant alternatives criterion=== | |||
{{Cross}} The ''']''' criterion states that "the election outcome remains the same even if a candidate who cannot win decides to run." IRV does not meet this criterion; in the general case, instant-runoff voting can be susceptible to ]: whether or not a candidate decides to run at all can affect the result even if the new candidate cannot themselves win.<ref name="wds">{{cite web|url=http://rangevoting.org/Burlington.html |title=Burlington Vermont 2009 IRV mayoral election |publisher=RangeVoting.org |date= |accessdate=2011-04-17}}</ref> | |||
A version of instant-runoff voting applying to the ranking of parties was first proposed for elections in Germany in 2013<ref>{{cite report |title=Anhörung zum Entwurf eines Gesetzes zur Abschaffung der Fünf-Prozent-Sperrklausel bei Landtagswahlen in Schleswig-Holstein |trans-title=Hearing on the draft law to abolish the five percent threshold in state elections in Schleswig-Holstein (Discussion paper) |last1=Breyer |first1=Patrick |date=November 2013 |publisher=Piratenfraktion im Schleswig-Holsteinischen Landtag |language=de |id=(Drs. 18/385) |chapter=Alternative II: Einführung einer Ersatzstimme |chapter-url=https://www.landtag.ltsh.de/infothek/wahl18/umdrucke/1900/umdruck-18-1916.pdf}}</ref> as ].{{Citation needed|date=September 2024}} | |||
===Independence of clones criterion=== | |||
{{Tick}} The ''']''' states that "the election outcome remains the same even if an identical candidate who is equally preferred decides to run." IRV meets this criterion.<ref>Green-Armytage, James (2004) </ref> | |||
== Voting method criteria == | |||
==Comparison to other voting systems== | |||
{{main|Voting criteria}} | |||
{{main|Comparison of instant runoff voting to other voting systems}} | |||
As shown by ], ], and others, it's usually impossible for a method to pass all of a number of seemingly reasonable properties, or criteria, at once. IRV is no exception: it passes some and fails others. The following criteria are satisfied and failed by IRV: | |||
==Tactical voting== | |||
===Is tactical voting possible?=== | |||
{{main|Comparison of instant runoff voting to other voting systems#Tactical voting}} | |||
=== Satisfied criteria === | |||
The ] demonstrates that no voting system can be entirely immune from tactical voting unless it is dictatorial (there is only one person who is able to choose the winner) or incorporates an element of chance. IRV is considered one of the less-manipulable voting systems, with theorist ] noting that "alternative vote is quite resistant to strategy"<ref name=tac1>John J. Bartholdi III, ] (1991) ''Social Choice and Welfare,'' vol. 8, p. 341-354</ref> and Australian political analyst Antony Green dismissing suggestions of tactical voting<ref> name=</ref>. James Green-Armytage finds<ref>{{cite web|url=http://www.econ.ucsb.edu/~armytage/hybrids.pdf|author=James Green-Armytage|title=Four Condorcet-Hare Hybrid Methods for Single-Winner Elections|accessdate=2011-05-31}}</ref> the alternative vote to be second most resistant to tactical voting among the methods tested, only beaten by a class of AV-Condorcet hybrids, although the alternative vote resists strategic withdrawal by candidates less well. | |||
==== Condorcet loser Criterion ==== | |||
By not meeting the monotonicity, Condorcet winner, and participation criteria, IRV theoretically could permit forms of tactical voting if voters had complete and reliable information about voters' full preferences.<ref name=tac3 /> However, ] claims that monotonicity failure can be misconstrued to suggest that "Having more voters rank candidate first, can cause to switch from being a winner to being a loser."<ref>{{cite web|url=http://archive.fairvote.org/?page=2261 |title=Monotonicity and IRV - Why the Monotonicity Criterion is of Little Import |publisher=Archive.fairvote.org |date= |accessdate=2011-04-17}}</ref> In fact, it is the change in lower candidates that is important: whether votes are shifted to the leading candidate, shifted to a fringe candidate, or discarded altogether is of no importance. What tactical voting would seek to achieve is to alter the order of eliminations in early rounds to ensure that the original winner is challenged by a stronger opponent in the final round. In a three-party election where voters for both the left and right prefer the centrist candidate to stop the "enemy" candidate winning, those voters on the left and right who care more about defeating the "enemy" than electing their own candidate may cast a tactical first preference vote for the centrist candidate. | |||
<blockquote>The ] criterion states that "if a candidate would lose a ] against every other candidate, then that candidate must not win the overall election". IRV (like all voting methods with a final runoff round) meets this criterion, since the Condorcet loser cannot win a runoff. </blockquote> | |||
==== Independence of clones criterion ==== | |||
The 2009 ] in ] provides an example in which strategy theoretically could have worked but would have been unlikely in practice. In that election, most supporters of the candidate who came in second (a Republican who led in first choices) preferred the ] winner, a Democrat, to the IRV winner, the Progressive Party nominee. If about 20% of the backers of the Republican candidate had insincerely raised the Democrat from their second choice to their first, the Republican would have dropped from first to third in first choices, and the Democrat would then have won the instant runoff.<ref name=tac3>Warren Smith (2009) </ref> But given that the Republican was a strong candidate who nearly won in the instant runoff, few of his backers would have risked giving up on his candidacy based on a chance, unknown before the fact, to elect the compromise Condorcet winner. | |||
<blockquote>The ''']''' states that "the election outcome remains the same even if an identical candidate who is equally preferred decides to run". Advocates have noted that IRV meeting this criterion<ref>{{cite web |last1=Green-Armytage |first1=James |date=2004 |title=A Survey of Basic Voting Methods |url=http://www.econ.ucsb.edu/~armytage/voting/survey.htm |archive-url=https://web.archive.org/web/20130603015026/http://www.econ.ucsb.edu/~armytage/voting/survey.htm |archive-date=3 June 2013}}</ref><ref name="TC">{{cite journal | last=Tideman | first=T. N. | title=Independence of clones as a criterion for voting rules | journal=Social Choice and Welfare | publisher=Springer Science and Business Media LLC | volume=4 | issue=3 | year=1987 | issn=0176-1714 | doi=10.1007/bf00433944 | pages=185–206 | quote=Among previously proposed voting rules, the alternative vote and the GOCHA rule are independent of clones.}}</ref> greatly reduces the impact of clones compared to ]. </blockquote> | |||
=== |
==== Later-no-harm criterion ==== | ||
<blockquote>The ] criterion states that "if a voter alters the order of candidates lower in his/her preference (e.g. swapping the second and third preferences), then that does not affect the chances of the most preferred candidate being elected". Instant runoff satisfies this criterion. </blockquote> | |||
{{main|Spoiler effect}} | |||
==== Majority criterion ==== | |||
The spoiler effect is where two or more equally popular candidates divide the vote, meaning that each receives fewer votes than a single opponent who is disliked by the majority of voters but has little competition. Proponents of IRV note that by reducing the spoiler effect, IRV makes it safe to vote honestly for marginal parties, and so discourages ]: under a plurality system, voters who sympathize most strongly with a marginal candidate are strongly encouraged to instead vote for a more popular candidate who shares some of the same principles, since that candidate has a much greater chance of being elected and a vote for the fringe candidate is largely wasted. In an IRV system this is no longer an issue since the voter can rank the marginal candidate first and the mainstream candidate second; in the likely event that the fringe candidate is eliminated, the vote is not wasted but is transferred to the second preference. In Australia's national elections in 2007, for example, the average number of candidates in a district was seven, and at least four candidates ran in every district; notwithstanding the fact that Australia only has two major political parties. Every seat was won with a majority of the vote, including several where results would have been different under plurality voting.<ref>http://results.aec.gov.au/13745/website/HouseResultsMenu-13745.htm</ref> | |||
<blockquote>The ] states that "if one candidate is preferred by an absolute majority of voters, then that candidate must win". Instant runoff also satisfies this criterion. </blockquote> | |||
==== Mutual majority criterion ==== | |||
==Proportionality== | |||
<blockquote>The ] criterion states that "if an absolute majority of voters prefer every member of a group of candidates to every candidate not in that group, then one of the preferred group must win". Note that this is satisfied because when all but one candidate that a mutual majority prefer is eliminated, the votes of the majority all flow to the remaining candidate, in contrast to ], where the majority would be treated as separate small groups. Instant runoff satisfies this criterion as well. </blockquote> | |||
{{Main|Comparison of instant runoff voting to other voting systems#Voting system results}} | |||
==== Resolvability criterion ==== | |||
IRV is not a proportional voting system. Like all winner-take-all voting systems, IRV tends to exaggerate the number of seats won by the largest parties; small parties without majority support in any given constituency are unlikely to earn seats in a legislature, although their supporters will be more likely to be part of the final choice between the two strongest candidates.<ref>{{cite web|url=http://www.mtholyoke.edu/acad/polit/damy/BeginnningReading/types.htm |title=Types of Voting Systems |publisher=Mtholyoke.edu |date=8 April 2005 |accessdate=6 May 2010}}</ref> A simulation of IRV in the ] by the ] concluded that the election would have altered the balance of seats between the three main parties, but the number of seats won by minor parties would have remained unchanged.<ref>{{cite news|url=http://www.guardian.co.uk/politics/2010/may/10/alternative-vote-minimal-impact-general-election|accessdate=1 April 2011|date=10 May 2010|title=Electoral reform: Alternative vote system would have had minimal impact on outcome of general election|publisher='']''|location=London|first=Alan|last=Travis}}</ref> | |||
<blockquote>The ] criterion states that "the probability of an exact tie must diminish as more votes are cast".{{Citation needed|date=September 2024}} </blockquote> | |||
=== Failed criteria === | |||
Australia, a nation with a long record of using IRV for election of legislative bodies, has had representation in its parliament broadly similar to that expected by ]. Medium-sized parties, such as the ], can co-exist with ] partners such as the ], and can compete against it without fear of losing seats to other parties due to vote splitting.<ref>, ], 2004 Election Guide. "''Such a long lasting Coalition would not have been possible under first part the post voting''"</ref> IRV is more likely to result in legislatures where no single party has an absolute majority of seats (a ]),{{citation needed|date=May 2011}} but does not generally produce as fragmented a legislature as a fully proportional system, such as is used for the ] or the ], where coalitions of numerous small parties are needed for a majority. | |||
{{Original research section|date=September 2024}} | |||
==== Condorcet winner criterion ==== | |||
==Costs== | |||
The ] criterion states that "if a candidate would win a ] against every other candidate, then that candidate must win the overall election". It is incompatible with the later-no-harm criterion, so IRV does not meet this criterion. | |||
{{Main|Comparison of instant runoff voting to other voting systems#Cost}} | |||
IRV is more likely to elect the Condorcet winner than ] and ] elections. The California cities of Oakland, San Francisco and San Leandro in 2010 provide an example; there were a total of four elections in which the plurality-voting leader in first-choice rankings was defeated, and in each case the IRV winner was the Condorcet winner, including a San Francisco election in which the IRV winner was in third place in first choice rankings. | |||
The costs of printing and counting ballot papers for an IRV election are no different from those of any other system using the same technology. However, the more-complicated counting system may encourage officials to introduce more advanced technology such as software counters or electronic voting machines. ] election officials outlined one-time costs of $857,000 to implement IRV for its elections in 2008, covering software and equipment, voter education and testing.<ref>{{cite web|url=http://www.ncvoter.net/downloads/Pierce_Co_WA_2008_IRV_Recap.pdf |title=Pierce County RCV Overview – City of LA Briefing |format=PDF |date= |accessdate=6 May 2010}}</ref> In 2009 the auditor of Washington counties reported that the ongoing costs of the system were not necessarily balanced by the costs of eliminating runoffs for most county offices, because those elections may be needed for other offices not elected by IRV.<ref>{{cite web|url=https://blog.thenewstribune.com/politics/2009/05/06/pierce-county-auditor-sees-savings-from-scrapping-ranked-choice-voting/ |title=County auditor sees savings from scrapping ranked choice voting |publisher=Blogs.thenewstribune.com |date=30 August 2006 |accessdate=6 May 2010}}</ref> Other jurisdictions have reported immediate cost savings.<ref>{{cite web|url=http://archive.fairvote.org/?page=2543 |title=FairVote - Wake County Answers on IRV Election Administration |publisher=Archive.fairvote.org |date= |accessdate=2011-04-17}}</ref> | |||
A particularly notable Condorcet failure occurred in the ]. | |||
It is possible to count IRV ballots by hand, and this is done for the Australian federal elections. Because multiple rounds of counting are required, the ballots must either be collected in one central location, or the interim results of each count must be collated and instructions sent out to each counting centre as to what action to take next.<ref>{{cite web|url=http://electionmathematics.org/ucvAnalysis/US/RCV-IRV/InstantRunoffVotingFlaws.pdf |title=Realities mar Instant Runoff Voting |publisher=Kathy Dopp |date=12 Feb 2009 |accessdate=1 Mar 2011}}</ref> In Australia counting takes place in each polling centre individually, and the results of the first-preference votes are aggregated by telephone;<ref>{{cite web|url=http://www.aec.gov.au/Voting/counting/index.htm |title=Counting the Votes |publisher=Aec.gov.au |date=2010-12-23 |accessdate=2011-04-17}}</ref> for subsequent rounds the papers are brought to one central counting centre. | |||
==== Independence of irrelevant alternatives ==== | |||
The perceived costs or cost savings of adopting an IRV system are commonly used by both supporters and critics. In the 2011 referendum on the Alternative Vote in the UK, the ] campaign launched with a claim that adopting the system would cost £250 million; commentators argued that this headline figure had been inflated by including £82 million for the cost of the referendum itself, and a further £130 million on the assumption that the UK would need to introduce electronic voting systems, when ministers had confirmed that there was no intention of implementing such technology, whatever the outcome of the election.<ref>{{cite news|url=http://www.bbc.co.uk/news/uk-politics-12564879 |title=No to AV campaign reject rivals' 'scare stories' claim |publisher=Bbc.co.uk |date=2011-02-24 |accessdate=2011-04-17}}</ref> Automated vote counting is seen by some to have a greater potential for election fraud;<ref>{{cite web|url=http://www.ncvoter.net |title=Nc Voter |publisher=Nc Voter |date= |accessdate=6 May 2010}}</ref> IRV supporters counter these claims with recommended audit procedures,<ref>{{cite web|url=http://www.fairvote.org/?page=2469 |title=Ranked Choice Voting and Election Integrity |publisher=FairVote |date=25 June 2008 |accessdate=6 May 2010}}</ref> or note that automated counting is not required for the system at all. | |||
The ''']''' criterion states that "the election outcome remains the same even if a candidate who cannot win decides to run." Instant-runoff voting violates this. In the general case, instant-runoff voting can be susceptible to ]: whether or not a candidate decides to run at all can affect the result even if the new candidate cannot themselves win. This is less likely to happen than under plurality, but much more likely than under the ].<ref name="Armytage 2014" /> | |||
==== Monotonicity criterion ==== | |||
Because it does not require two separate votes, IRV is accepted to cost less than ] primary/general or general/runoff election systems.<ref>http://sfpl4.sfpl.org/pdffiles/March5_2002.pdf</ref> | |||
{{Further|Monotonicity criterion#Instant-runoff voting and the two-round system are not monotonic}} | |||
The ''']''' says that a voter ranking a candidate higher on their ballot should not cause that candidate to lose and conversely, that a voter ranking a candidate lower on their ballot should not help that candidate win. The exact probability of a monotonicity failure depends on the circumstances, but with 3 major candidates, the probabilities range from 15 percent under the ]<ref name="Miller">{{cite conference|title=Monotonicity failure in IRV elections with three candidates|last=Miller|first=Nicholas R.|year=2012|book-title=World meeting of the public choice societies}}</ref>{{rp|Table 6}} to 8.5 percent in the case of a strict ].<ref>{{cite journal |last1=Lepelley |first1=Dominique |last2=Chantreuil |first2=Frederic |last3=Berg |first3=Sven |year=1996 |title=The likelihood of monotonicity paradoxes in run-off elections |journal=Mathematical Social Sciences |volume=31 |issue=3 |pages=133–146 |doi=10.1016/0165-4896(95)00804-7}}</ref> | |||
==== Participation criterion ==== | |||
==Negative campaigning== | |||
The ''']''' says that candidates should not lose as a result of having "too many voters"—a set of ballots that all rank A>B should not switch the election winner from B to A. IRV fails this criterion. In his 1984 study, mathematician Depankar Ray found that in elections where IRV elects a different candidate from plurality, that there was an estimated 50 percent probability that some voters would have gotten a more preferable outcome if they had not participated.<ref name="auto4">{{cite journal |last=Ray |first=Depankar |year=1986 |title=On the practical possibility of a 'no show paradox' under the single transferable vote |journal=Mathematical Social Sciences |volume=11 |issue=2 |pages=183–189 |doi=10.1016/0165-4896(86)90024-7}}</ref> | |||
{{Main|Comparison of instant runoff voting to other voting systems#Political parties}} | |||
==== Reversal symmetry criterion ==== | |||
John Russo, Oakland City Attorney, argued in the ] on July 24, 2006 that "Instant runoff voting is an antidote to the disease of negative campaigning.{{Citation needed|date=November 2010}} IRV led to San Francisco candidates campaigning more cooperatively. Under the system, their candidates were less likely to engage in negative campaigning because such tactics would risk alienating the voters who support 'attacked' candidates", reducing the chance that they would support the attacker as a second or third choice.<ref>{{cite news| url=http://www.nytimes.com/2004/09/30/national/30runoff.html | work=The New York Times | first=Dean E. | last=Murphy | title=New Runoff System in San Francisco Has the Rival Candidates Cooperating | date=30 September 2004}}</ref><ref>{{Dead link|date=May 2010}}</ref> | |||
The ] states that the first- and last-place candidates should switch places if every ballot is reversed. In other words, it should not matter whether voters rank candidates from best-to-worst and select the best candidate, or whether they rank them worst-to-best and then select the least-bad candidate. | |||
IRV fails this criterion: it is possible to construct an election where reversing the order of every ballot does not alter the final winner; that is, the first- and last-place finishers, according to IRV, are the same candidate.<ref>{{cite book |last=Felsenthal |first=Dan S. |title=Electoral Systems |chapter=Review of Paradoxes Afflicting Procedures for Electing a Single Candidate |date=2012 |series=Studies in Choice and Welfare |pages=19–91 |editor-last=Felsenthal |editor-first=Dan S. |chapter-url=http://link.springer.com/10.1007/978-3-642-20441-8_3 |access-date=2024-11-08 |location=Berlin, Heidelberg |publisher=Springer Berlin Heidelberg |doi=10.1007/978-3-642-20441-8_3 |isbn=978-3-642-20440-1 |editor2-last=Machover |editor2-first=Moshé}}</ref> | |||
No formal studies have been conducted in the United States. Internationally, Benjamin Reilly suggests instant runoff voting eases ethnic conflict in divided societies.<ref>{{cite web|url=http://muse.jhu.edu/login?uri=/journals/journal_of_democracy/v013/13.2reilly.html |title=Project MUSE |publisher=Muse.jhu.edu |date= |accessdate=6 May 2010}}</ref> This feature was a leading argument for why ] adopted instant runoff voting.<ref>, Electoral Knowledg Network</ref> | |||
=== Comparison to other voting systems === | |||
Critics allege there is a lack of evidence that such an effect occurs as often as suggested.<ref>{{cite web| url = http://www.beyondchron.org/news/index.php?itemid=1468 | title = Instant Runoff Voting Not Meeting Expectations | first = John | last = Dunbar | date = 17 November 2005}}</ref> Indeed, Lord Alexander's objections to the conclusions of the British Independent Commission on the Voting System's cites the example of Australia saying "their politicians tend to be, if anything, more blunt and outspoken than our own." | |||
{{Main article|Comparison of electoral systems}} | |||
{{Comparison of Schulze to preferential voting systems}} | |||
== |
==Examples== | ||
The first example is a fictional one for the purpose of demonstrating the principle of instant runoff. The other examples are drawn from the results of real-life elections. | |||
{{Main|Comparison of instant runoff voting to other voting systems#Voter power}} | |||
=== Tennessee capital example === | |||
In ] arguments over IRV in letters to newspapers included the belief that IRV "gives minority candidate voters two votes," because some voters' ballots may count for their first choice in the first round and a lesser choice in a later round.<ref>{{cite web | url = http://www.migreens.org/hvgreens/aa-irv01.htm | title = History of Preferential Voting in Ann Arbor | first = Benjamin | last = Walter}}</ref> The argument that IRV represents ] is sometimes used in arguments over the 'fairness' of the system, and has led to several legal challenges in the United States. The argument was addressed and rejected by a Michigan court in 1975; in '']'', the court held "majority preferential voting" (as IRV was then known) to be in compliance with the Michigan and United States constitutions, writing: | |||
{{Tenn_voting example}} | |||
{{quote|Under the 'M.P.V. System', however, no one person or voter has more than one effective vote for one office. No voter's vote can be counted more than once for the same candidate. In the final analysis, no voter is given greater weight in his or her vote over the vote of another voter, although to understand this does require a conceptual understanding of how the effect of a 'M.P.V. System' is like that of a run-off election. The form of majority preferential voting employed in the City of Ann Arbor's election of its Mayor does not violate the one-man, one-vote mandate nor does it deprive anyone of equal protection rights under the Michigan or United States Constitutions.|<ref>{{cite web|url=http://archive.fairvote.org/?page=397 |title=Ann Arbor Law Suit |publisher=FairVote |date= |accessdate=10 May 2011}}</ref>}} | |||
It takes three rounds to determine a winner in this election. | |||
==Invalid ballots and exhausted ballots== | |||
] | |||
{{Main|Comparison of instant runoff voting to other voting systems#Ballot issues}} | |||
'''Round 1''' – In the first round no city gets a majority: | |||
{| class="wikitable" | |||
!Votes in round/ | |||
City Choice | |||
!1st | |||
|- | |||
|Memphis | |||
| style="background:#dfb;" |42% | |||
|- | |||
|Nashville | |||
| style="background:#dfb;" |26% | |||
|- | |||
|Knoxville | |||
| style="background:#dfb;" |17% | |||
|- | |||
|Chattanooga | |||
| style="background:#fbb;" |''15%'' | |||
|} | |||
If one of the cities had achieved a majority vote (more than half), the election would end there. If this were a first-past-the-post election, Memphis would win because it received the most votes. But IRV does not allow a candidate to win on the first round without having an absolute majority of the active votes. Since no city has won yet, the city with the least first-place support (Chattanooga) is eliminated from consideration. The ballots that listed Chattanooga as first choice are added to the totals of the second-choice selection on each ballot. | |||
] | |||
'''Round 2''' – In the second round of tabulation, Chattanooga's 15% of the total votes have been added to the second choices selected by the voters for whom that city was first-choice (in this example Knoxville): | |||
{| class="wikitable" | |||
!Votes in round/ | |||
City Choice | |||
!1st | |||
!2nd | |||
|- | |||
|Memphis | |||
| style="background:#dfb;" |42% | |||
| style="background:#dfb;" |42% | |||
|- | |||
|Nashville | |||
| style="background:#dfb;" |26% | |||
| style="background:#fbb;" |''26%'' | |||
|- | |||
|Knoxville | |||
| style="background:#dfb;" |17% | |||
| style="background:#dfb;" |32% | |||
|- | |||
|Chattanooga | |||
| style="background:#fbb;" |''15%'' | |||
| | |||
|} | |||
In the first round, Memphis was first, Nashville was second and Knoxville was third. With Chattanooga eliminated and its votes redistributed, the second round finds Memphis still in first place, followed by Knoxville in second and Nashville has moved down to third place. No city yet has secured a majority of votes, so the now last placed Nashville is eliminated and the ballots currently counting for Nashville are added to the totals of Memphis or Knoxville based on which city is ranked next on that ballot. | |||
'''Round 3''' | |||
Because the ballot marking is more complex, there can be an increase in spoiled ballots. In Australia, voters are required to write a number beside every candidate, and error rates can be five times higher than plurality voting elections<ref>{{cite web|author=|url=http://www.no2av.org/why-vote-no/av-myth-busting/ |title=Busting the Myths of AV |publisher=No2av.org |date=2010-10-25 |accessdate=2011-04-17}}</ref> Since Australia has compulsory voting, however, it is difficult to tell how many ballots are deliberately spoiled.<ref>{{cite web|author=|url=http://blogs.abc.net.au/antonygreen/2011/02/informal-voting-two-ways-of-allowing-more-votes-to-count.html |title=Informal Voting - Two Ways of Allowing More Votes to Count |publisher=ABC Elections |date=2011-02-28 |accessdate=2011-08-15}}</ref> Most jurisdictions with IRV do not require complete rankings and may use columns to indicate preference instead of numbers. In American elections with IRV, more than 99% of voters typically cast a valid ballot.<ref>{{cite web|author=|url=http://politicalreform.newamerica.net/files/irvracememo.pdf |title=Instant Runoff Voting and Its Impact on Racial Minorities |publisher=New America Foundation |date=2008-08-01 |accessdate=2011-08-15}}</ref> | |||
] | |||
As Memphis and Knoxville are the only two cities remaining in the contest, this round will be the final round. In this example the second-choice of the Nashville voters is Chattanooga, which is already eliminated. Therefore, the votes are added to their third-choice: Knoxville. The third round of tabulation yields the following result: | |||
{| class="wikitable" | |||
!Votes in round/ | |||
City Choice | |||
!1st | |||
!2nd | |||
!3rd | |||
|- | |||
|Memphis | |||
| style="background:#dfb;" |42% | |||
| style="background:#dfb;" |42% | |||
| style="background:#fbb;" |''42%'' | |||
|- | |||
|Nashville | |||
| style="background:#dfb;" |26% | |||
| style="background:#fbb;" |''26%'' | |||
|- | |||
|Knoxville | |||
| style="background:#dfb;" |17% | |||
| style="background:#dfb;" |32% | |||
| style="background:#bfb;" |'''58%''' | |||
|- | |||
|Chattanooga | |||
| style="background:#fbb;" |''15%'' | |||
|} | |||
'''Result:''' Knoxville, which was running third in the first tabulation, has moved up from behind to take first place in the third and final round. The winner of the election is '''Knoxville'''. However, if 6% of voters in Memphis were to put Nashville first, the winner would be Nashville, a preferable outcome for voters in Memphis. This is an example of potential tactical voting, though one that would be difficult for voters to carry out in practice. Also, if 17% of voters in Memphis were to stay away from voting, the winner would be Nashville. This is an example of IRV failing the participation criterion. | |||
For comparison, note that traditional ] would elect Memphis, even though most citizens consider it the worst choice, because 42% is larger than any other single city. As Nashville is a Condorcet winner, ] would elect Nashville. A ] would have a runoff between Memphis and Nashville where Nashville would win, too. | |||
==Robert's Rules of Order== | |||
{{Main|Comparison of instant runoff voting to other voting systems#Rules of Order}} | |||
===1990 Irish presidential election=== | |||
The sequential elimination method used by IRV is described in ''] Newly Revised, 10th edition.''<ref name="autogenerated1">{{cite book|ref=harv|year=2000|pages=411–414|title=Robert's Rules of Order Newly Revised, 10th edition|isbn=978-0738203072|publisher=Da Capo Press|last=Robert|first=Henry}}</ref> as an example of "]", a term covering "any of a number of voting methods by which, on a single ballot when there are more than two possible choices, the second or less-preferred choices of voters can be taken into account if no candidate or proposition attains a majority. While it is more complicated than other methods of voting in common use and is not a substitute for the normal procedure of repeated balloting until a majority is obtained, preferential voting is especially useful and fair in an election by mail if it is impractical to take more than one ballot. In such cases it makes possible a more representative result than under a rule that a plurality shall elect...."Preferential voting has many variations. One method is described ... by way of illustration."<ref>{{harvnb|Robert|2000|p=411}}</ref> And then the instant runoff voting method is detailed.<ref>{{harvnb|Robert|2000|pp=412–413}}</ref> | |||
{{See also|Irish presidential election, 1990}} | |||
The ] provides a simple example of how instant-runoff voting can produce a different result from ] and prevent some spoiler effects associated with ]. The three major candidates were ] of ], ] of ], and ] of the ]. After the first count, Lenihan had the largest share of first-choice rankings. Currie had the fewest votes and was eliminated. After this, Robinson received 82 percent of Currie's votes, thereby overtaking Lenihan. | |||
{| class="wikitable" | |||
|+Irish presidential election, 1990<ref>{{cite web |title=Presidential Election November 1990 |url=http://www.electionsireland.org/result.cfm?election=1990P&cons=194 |access-date=23 November 2009 |work=ElectionsIreland.org}}</ref> | |||
!Candidate | |||
! colspan="2" |Round 1 | |||
! colspan="2" |Round 2 | |||
|- | |||
!] | |||
|612,265 | |||
|38.9% | |||
|'''817,830''' | |||
|'''51.6%''' | |||
|- | |||
!] | |||
|694,484 | |||
|43.8% | |||
|731,273 | |||
|46.2% | |||
|- | |||
!] | |||
|267,902 | |||
|16.9%{{Xmark}} | |||
| colspan="2" |''Eliminated'' | |||
|- | |||
!Exhausted ballots | |||
|9,444 | |||
|0.6% | |||
|34,992 | |||
|2.2% | |||
|- | |||
!Total | |||
|1,584,095 | |||
|100% | |||
|1,584,095 | |||
|100% | |||
|} | |||
<!--no cite: since only 3 candidates just simple ratio of extra votes in 2nd count.-->{{clear}} | |||
===2014 Prahran election (Victoria)=== | |||
''Robert's Rules'' continues: "The system of preferential voting just described should not be used in cases where it is possible to follow the normal procedure of repeated balloting until one candidate or proposition attains a majority. Although this type of preferential ballot is preferable to an election by plurality, it affords less freedom of choice than repeated balloting, because it denies voters the opportunity of basing their second or lesser choices on the results of earlier ballots, and because the candidate or proposition in last place is automatically eliminated and may thus be prevented from becoming a compromise choice."<ref name=roberts414>{{harvnb|Robert|2000|p=414}}</ref> Two other books on parliamentary procedure take a similar stance, disapproving of plurality voting and describing preferential voting as an option, if authorized in the bylaws, when repeated balloting is impractical: ]<ref>{{cite parl|title=TSC|pages=148|edition=4th}}</ref> and ].<ref>{{cite parl|title=RID|pages=145|edition=1985|year=1985}}</ref> | |||
Another real-life example of IRV producing results different from first-past-the-post can be seen in the ] in ]. In this rare instance, the candidate who initially placed third, (] candidate ]), won the seat.<ref name="PrahranResults2">{{cite web |title=State Election 2014: Prahran District (Distribution of preference votes) |url=https://www.vec.vic.gov.au/Results/State2014/distributionPrahranDistrict.html |work=Victorian Electoral Commission |access-date=25 July 2018 |archive-date=25 July 2018 |archive-url=https://web.archive.org/web/20180725092627/https://www.vec.vic.gov.au/Results/State2014/distributionPrahranDistrict.html |url-status=dead }}</ref> In the 7th and final round, Hibbins narrowly defeated ] candidate Clem Newton-Brown by a margin of 277 votes. | |||
{| class="wikitable sortable" | |||
==Global use== | |||
!Candidate | |||
{{main|History and use of instant-runoff voting}} | |||
! colspan="2" |1st | |||
{{see also|Table of voting systems by country}} | |||
!2nd | |||
!3rd | |||
!4th | |||
!5th | |||
!6th | |||
! colspan="2" |7th | |||
|- | |||
|] (]) | |||
|44.8% | |||
|'''16,582''' | |||
|'''16,592''' | |||
|'''16,644''' | |||
|'''16,726''' | |||
|'''16,843''' | |||
|'''17,076''' | |||
|18,363 | |||
|49.6% | |||
|- | |||
|Neil Pharaoh (]) | |||
|25.9% | |||
|'''9,586''' | |||
|'''9,593''' | |||
|'''9,639''' | |||
|'''9,690''' | |||
|'''9,758''' | |||
|9,948{{Xmark}} | |||
| colspan="2" |''Eliminated'' | |||
|- | |||
|] (]) | |||
|24.8% | |||
|9,160 | |||
|9,171 | |||
|9,218 | |||
|9,310 | |||
|9,403 | |||
|'''9,979''' | |||
|'''18,640''' | |||
|'''50.4%''' | |||
|- | |||
|Eleonora Gullone (]) | |||
|2.3% | |||
|837 | |||
|860 | |||
|891 | |||
|928 | |||
|999{{Xmark}} | |||
| colspan="3" |''Eliminated'' | |||
|- | |||
|Alan Walker (]) | |||
|0.8% | |||
|282 | |||
|283 | |||
|295{{Xmark}} | |||
| colspan="5" |''Eliminated'' | |||
|- | |||
|Jason Goldsmith (]) | |||
|0.7% | |||
|247 | |||
|263 | |||
|316 | |||
|349{{Xmark}} | |||
| colspan="4" |''Eliminated'' | |||
|- | |||
|Steve Stefanopoulos (]) | |||
|0.6% | |||
|227 | |||
|241{{Xmark}} | |||
| colspan="6" |''Eliminated'' | |||
|- | |||
|Alan Menadue (]) | |||
|0.2% | |||
|82{{Xmark}} | |||
| colspan="7" |''Eliminated'' | |||
|- | |||
!Total | |||
|'''100%''' | |||
|'''37,003''' | |||
|} | |||
===2009 Burlington mayoral election=== | |||
===Australia=== | |||
{{See also|2009 Burlington mayoral election}} | |||
{{see also|Australian electoral system|Electoral systems of the Australian states and territories}} | |||
{| class=wikitable style="text-align:right; float:right; margin-left:1em" | |||
Instant-runoff voting is used for national elections in Australia to elect members of the ]. The ] uses a modified form, combining it with a ] system (the ]); candidates are eliminated until the remaining parties can be said to have a sufficient proportion of the vote to earn a seat.<ref name="Australian Electoral Commission"/> | |||
|+ Burlington mayoral election, 2009 (round-by-round analysis of votes) | |||
|- | |||
!colspan=2 |Candidates | |||
!colspan=2 |1st round | |||
!colspan=2 |2nd round | |||
!colspan=2 |3rd round | |||
|- | |||
!'''Candidate''' | |||
!Party | |||
!Votes | |||
!± | |||
!Votes | |||
!± | |||
!Votes | |||
!± | |||
|- {{Party shading/Vermont Progressive}} | |||
| style="text-align:left;"| ''']''' | |||
| style="text-align:left;"| ] | |||
| 2585 | |||
| +2585 | |||
| 2981 | |||
| +396 | |||
| '''4313''' | |||
| +1332 | |||
|- {{Party shading/Republican}} | |||
| style="text-align:left;"| Kurt Wright | |||
| style="text-align:left;"| ] | |||
| '''2951''' | |||
| +2951 | |||
| '''3294''' | |||
| +343 | |||
| 4061 | |||
| +767 | |||
|- {{Party shading/Democratic}} | |||
| style="text-align:left;"| Andy Montroll | |||
| style="text-align:left;"| ] | |||
| 2063 | |||
| +2063 | |||
| 2554 | |||
| +491 | |||
| 0 | |||
| −2554 | |||
|- {{Party shading/Independent}} | |||
| style="text-align:left;"| Dan Smith | |||
| style="text-align:left;"| ] | |||
| 1306 | |||
| +1306 | |||
| 0 | |||
| −1306 | |||
|- | |||
! style="text-align:left;" | Others | |||
| | |||
| 71 | |||
| +71 | |||
| 0 | |||
| −71 | |||
|- | |||
! style="text-align:left;" | ] | |||
| | |||
| 4 | |||
| +4 | |||
| 151 | |||
| +147 | |||
| 606 | |||
| +455 | |||
|} | |||
Under Burlington, Vermont's second-ever IRV mayoral election in 2009, the winner, Bob Kiss, was elected over the more popular Andy Montroll as a result of a first-round spoiler effect. | |||
] touted the 2009 election as one of its major success stories,<ref name=":4">{{Cite news |last=Etnier |first=Carl |date=6 March 2009 |title=Instant runoff was success |url=https://www.rutlandherald.com/articles/instant-runoff-was-success/ |access-date=17 March 2018 |work=Rutland Herald }}{{Dead link|date=September 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> claiming it helped the city save on costs of a traditional runoff<ref name=":4" /><ref name=":5">{{Cite news |last=Totten |first=Shay |title=Burlington Residents Seek Repeal of Instant Runoff Voting |url=https://www.sevendaysvt.com/vermont/burlington-residents-seek-repeal-of-instant-runoff-voting/Content?oid=2177125 |access-date=17 March 2018 |work=Seven Days |language=en |quote=We waited to bring in the signatures because we didn't want this to be about Kurt Wright losing after being ahead, or Andy Montroll who had more first and second place votes and didn't win. We wanted this to be about IRV.}}</ref> and prevented a ],<ref name=":02">{{Cite web |last=Bouricius |first=Terry |date=17 March 2009 |title=Response to Faulty Analysis of Burlington IRV Election |url=http://www.fairvote.org/response-to-faulty-analysis-of-burlington-irv-election |access-date=1 October 2017 |website=FairVote.org |quote=successfully prevented the election of the candidate who would likely have won under plurality rules, but would have lost to either of the other top finishers in a runoff}}</ref> although later analysis showed that without Wright in the election, Montroll would have defeated Kiss in a one-on-one race.<ref name=":10">{{Cite journal |last=Lewyn |first=Michael |date=2012 |title=Two Cheers for Instant Runoff Voting |journal=Phoenix L. Rev. |language=en |volume=6 |page=117 |ssrn=2276015 |quote=election where Democratic candidate for mayor was Condorcet winner but finished third behind Republican and 'Progressive{{'-}}}}</ref> | |||
===Canada=== | |||
IRV is used to elect the leaders of two political parties in Canada, the ]<ref>{{cite web|url=https://www.liberal.ca/newsroom/party-news/liberals-vote-overwhelmingly-in-favour-of-one-member-one-vote-2/ |title=Liberals vote overwhelmingly in favour of one-member, one-vote |publisher=Liberal.ca |date=2009-05-02 |accessdate=2011-04-17}}</ref> and the ]. Canadian Prime Minister ] won an IRV election to become party leader in the ]. | |||
] and ] criticized the election results as revealing several ] associated with instant-runoff voting, noting that Kiss was elected as a result of 750 votes ] (ranking Kiss in last place).<ref>{{Cite journal |last1=Felsenthal |first1=Dan S. |last2=Tideman |first2=Nicolaus |date=2014 |title=Interacting double monotonicity failure with direction of impact under five voting methods |journal=Mathematical Social Sciences |volume=67 |pages=57–66 |doi=10.1016/j.mathsocsci.2013.08.001 |issn=0165-4896 |quote=A display of non-monotonicity under the Alternative Vote method was reported recently, for the March 2009 mayoral election in Burlington, Vermont.}}</ref><ref name=":8">{{Cite journal |last1=Ornstein |first1=Joseph T. |last2=Norman |first2=Robert Z. |date=1 October 2014 |title=Frequency of monotonicity failure under Instant Runoff Voting: estimates based on a spatial model of elections |journal=Public Choice |language=en |volume=161 |issue=1–2 |pages=1–9 |doi=10.1007/s11127-013-0118-2 |issn=0048-5829 |s2cid=30833409 |quote=Although the Democrat was the Condorcet winner (a majority of voters preferred him in all two way contests), he received the fewest first-place votes and so was eliminated ... 2009 mayoral election in Burlington, VT, which illustrates the key features of an upward monotonicity failure}}</ref> | |||
===Fiji=== | |||
Instant-runoff voting is used for national elections to elect members of the ].<ref name="Fiji Constitution, Section 541"/> In Fiji, each voter casts ballots in two elections: one for the minority of seats that are elected by universal suffrage and the remaining in one of the communal constituencies reserved to different ethnic groups. | |||
Several ] advocates branded the election a failure after Kiss was elected, despite 54 percent of voters voting for Montroll over Kiss,<ref>{{Cite journal |last1=Bristow-Johnson |first1=Robert |date=2023 |title=The failure of Instant Runoff to accomplish the purpose for which it was adopted: a case study from Burlington Vermont |journal=Constitutional Political Economy |volume=34 |issue=3 |pages=378–389 |doi=10.1007/s10602-023-09393-1}}</ref> violating the principle of ].<ref name=":10" /><ref>{{Cite book |last=Ellenberg |first=Jordan |url=https://archive.org/details/hownottobewrongp0000elle |title=How Not to Be Wrong: The Power of Mathematical Thinking |date=29 May 2014 |publisher=Penguin |isbn=9780698163843 |page= |language=en |quote=a majority of voters liked the centrist candidate Montroll better than Kiss, and a majority of voters liked Montroll better than Wright ... yet Montroll was tossed in the first round. |url-access=registration}}</ref><ref>{{Cite SSRN |last=Stensholt |first=Eivind |date=7 October 2015 |title=What Happened in Burlington? |ssrn=2670462 |quote=K was elected even though M was a clear Condorcet winner and W was a clear Plurality winner.}}</ref><ref name=":6">{{Cite news |last=Dopp |first=Kathy |date=10 June 2009 |title=IRV much worse than old runoffs |url=https://www.aspentimes.com/news/irv-much-worse-than-old-runoffs/ |access-date=17 March 2018 |work=The Aspen Times |language=en}}</ref> | |||
===India=== | |||
IRV is used in numerous ] environments, including the election of the ] by the members of the ] and of the ]s – the ] legislatures.<ref>{{cite web|author=Posted by swapnil |url=http://swapsushias.blogspot.com/2010/10/presidents-of-indiarashtrapati.html |title=IAS OUR DREAM: Presidents of India, Rashtrapati Bhavan, Trivia |publisher=Swapsushias.blogspot.com |date=2010-10-29 |accessdate=2010-12-03}}</ref> | |||
<!-- Lint | |||
===Ireland=== | |||
{{Election box ranked choice candidate with party link|party=Vermont Progressive Party|candidate=]|maxround=3|maxvotes=4313|maxvotespercent=48.0|r1votes=2585|fullwidthvotes=4500}} | |||
While most ] uses the ] (STV),<ref>{{cite web|url=http://www.environ.ie/en/LocalGovernment/Voting/PublicationsDocuments/FileDownLoad,1895,en.pdf|title=Guide to Ireland’s PR-STV Electoral System|last=Franchise Section|date=February 2011.|publisher=Department of the Environment, Heritage and Local Government|accessdate=29 April 2011}}</ref> in single-winner contests this reduces to IRV.<ref name="Muckerras">{{cite journal|last=Muckerras|first=Malcolm|coauthors=William Muley|year=1998|title=Preferential Voting in Australia, Ireland and Malta|journal=Griffith Law Review|volume=7|issue=2|pages=225–248|url=http://kirra.austlii.edu.au/au/journals/GriffLawRw/1998/14.pdf}}</ref> This is the case in all ]<ref name="Muckerras"/> and ] by-elections,<ref name="panelact1947"> Irish Statute Book</ref> and most ]s<ref name="Muckerras"/> In the rare event of multiple simultaneous vacancies in a single ], a single STV by-election may be held;<ref> Irish Statute Book</ref> for Seanad panels, multiple IRV by-elections are held.<ref name="panelact1947"/> | |||
{{Election box ranked choice candidate with party link|party=Vermont Republican Party|candidate=Kurt Wright|maxround=3|maxvotes=4061|maxvotespercent=45.2|r1votes=2951|fullwidthvotes=4500}} | |||
{{Election box ranked choice candidate with party link|party=Vermont Democratic Party|candidate=Andy Montroll|maxround=2|maxvotes=2554|maxvotespercent=28.4|r1votes=2063|fullwidthvotes=4500}} | |||
{{Election box ranked choice candidate with party link|party=Independent politician|candidate=Dan Smith|maxround=1|maxvotes=1306|maxvotespercent=14.5|r1votes=1306|fullwidthvotes=4500}} | |||
{{Election box ranked choice candidate with party link|party=Green Party (United States)|candidate=James Simpson|maxround=1|maxvotes=35|maxvotespercent=0.4|r1votes=35|fullwidthvotes=4500}} | |||
{{Election box ranked choice candidate with party not linked|party=Write-in|candidate=|maxround=1|maxvotes=36|maxvotespercent=0.4|r1votes=36|fullwidthvotes=4500}} | |||
{{Election box ranked choice exhausted no party no change with bar|maxvotes=606|maxvotespercent=6.7|r1votes=4|fullwidthvotes=4500|votes=606|percentage=6.7}} | |||
{{Election box ranked choice end}}--> | |||
== |
== See also == | ||
* ], a proportional method that reduces to instant runoff in single-winner elections. | |||
IRV is used in the elections of ]s and councillors in single-member wards in some New Zealand cities such as Dunedin and Wellington. Multi-member wards in these cities use STV.<ref name="Elections - 2007 Final Results"/> | |||
* ] | |||
* ] | |||
* ] (AV+), or alternative vote top-up, proposed by the ] in the UK | |||
* ] | |||
* ] | |||
== Notes == | |||
IRV, under the name Alternative Vote, was one of the four alternative systems available (alongside ], ] and ]) in the ] to elect MP's to the ]. It came third of the alternative systems (ahead of SM) with 6.6% of the vote. IRV, under the name Preferential Vote, will again be one of the four alternative systems available in the upcoming ]. | |||
{{notelist}} | |||
===Papua New Guinea=== | |||
Since 2003 the national parliament of ] has been elected using an IRV variant called Limited Preferential Voting, where voters are limited to ranking three candidates.<ref>{{cite web|url=http://archive.fairvote.org/articles/papuanewguinea.htm |title=Center for Voting and Democracy |publisher=Archive.fairvote.org |date= |accessdate=2011-04-17}}</ref><ref>{{cite web|url=http://aceproject.org/ero-en/regions/pacific/PG/Papua_new_guinea_leaflet.pdf/view |title=Limited Preferential Voting |publisher=Aceproject.org |date= |accessdate=2010-10-03}}</ref> | |||
===United Kingdom=== | |||
In the United Kingdom the system is commonly known as the alternative vote. It is used to elect the leaders of the ] and the ]. (The leader of the ] is elected under a similar system, a variant of the ].) It is also used for ], in which ]s are selected for that body.<ref name="Notice of Conservative Hereditary Peers' By-Election to the House of Lords">{{cite web| url = http://www.parliament.uk/documents/lords-information-office/holnotice20100601.pdf |title = Notice of Conservative Hereditary Peers' By-Election to the House of Lords |publisher=House of Lords}}</ref> AV is also used by members of parliament to elect the chairmen of select committees and the ]. The Speaker of the House of Commons is elected by the exhaustive ballot. | |||
In 2010 the Conservative/Liberal Democrat coalition government agreed to hold a ],<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/uk_news/politics/election_2010/8675848.stm |title=BBC's Q&A: The Conservative-Lib Dem coalition |publisher=BBC |date=2010-05-13 |accessdate=2010-10-03}}</ref> held on 5 May 2011.<ref>{{cite news|author=Norman Smith Chief political correspondent, BBC Radio 4 |url=http://news.bbc.co.uk/1/hi/politics/10483841.stm |title=Voting reform referendum planned for next May |publisher=BBC|date=2010-07-02 |accessdate=2010-10-03}}</ref> The proposal would have affected the way in which ] are elected to the ] at Westminster. The ] was a vote against adoption of the alternative vote by a margin of 67.9 percent to 32.1 percent.<ref> Referendum result</ref> | |||
===United States=== | |||
{{seealso2|] for occasional related news in the United States}} | |||
IRV is used by several jurisdictions in the United States, including ],<ref name=mpr20090510/> ],<ref name=or2010/> and ] and ].<ref name=mpr20090510/> United States private associations that use IRV<ref name="Organizations & Corporations"/> include the ]s for science fiction,<ref name="Oscars Copy Hugos"/> the ] in selection of the Oscar for Best Picture,<ref name="www.oscars.org"/> and more than fifty colleges and universities for student elections.<ref>instantrunoff.com</ref> | |||
==Similar systems== | |||
===Runoff voting=== | |||
The term ''instant runoff voting'' is derived from the name of a class of voting systems called runoff voting. In runoff voting voters do not rank candidates in order of preference on a single ballot. Instead a similar effect is achieved by using multiple rounds of voting. All multi-round runoff voting systems allow voters to change their preferences in each round, incorporating the results of the prior round to influence their decision. This is not possible in IRV, as participants vote only once, and this prohibits certain forms of ] that can be prevalent in 'standard' runoff voting. | |||
===Exhaustive ballot=== | |||
A system closer to IRV is the ]. In this system—one familiar to fans of the television show ]—one candidate is eliminated after each round, and many rounds of voting are used, rather than just two.<ref>{{cite web|url=http://www.securevote.com.au/gloss_of_terms.html#e |title=Glossary: Exhaustive ballot |publisher=Securevote.com.au |date= |accessdate=6 May 2010}}</ref> Because holding many rounds of voting on separate days is generally expensive, the exhaustive ballot is not used for large scale, public elections. | |||
===Two-round systems=== | |||
The simplest form of runoff voting is the ], which typically excludes all but two candidates after the first round, rather than gradually eliminating candidates over a series of rounds. Eliminations can occur with or without allowing and applying preference votes to choose the final two candidates. A second round of voting or counting is only necessary if no candidate receives an overall majority of votes. This system is used in France and the Finnish presidential election. | |||
===Contingent vote (supplementary)=== | |||
] | |||
The ], also known as '''Top-two IRV''', or ''batch-style'', is the same as IRV except that if no candidate achieves a majority in the first round of counting, all but the two candidates with the most votes are eliminated, and the second preferences for those ballots are counted. As in IRV, there is only one round of voting. | |||
Under a variant of contingent voting used in ], and the elections for ] in the United Kingdom, voters rank a specified maximum number of candidates. In London, the ], allows voters to express first and second preferences only. Sri Lankan voters rank up to three candidates for the ], in a ]. | |||
While similar to "sequential elimination" IRV, top-two can produce different results. Excluding more than one candidate after the first count might eliminate a candidate who would have won under sequential elimination IRV. Restricting voters to a maximum number of preferences is more likely to exhaust ballots if voters do not anticipate which candidates will finish in the top two. This can encourage voters to vote more ], by ranking at least one a candidate they think is likely to win. | |||
Conversely, a practical benefit of 'contingent voting' is expediency and confidence in the result with only two rounds. Particularly in elections with few (e.g., fewer than 100) voters, numerous ties can destroy confidence. Heavy use of tie-breaking rules leaves uncomfortable doubts over whether the winner might have changed if a recount was performed. | |||
===In a larger runoff process=== | |||
IRV may also be part of a larger runoff process: | |||
* Some jurisdictions that hold runoff elections allow absentee (only) voters to submit IRV ballots, because the interval between votes is too short for a second round of absentee voting. IRV ballots enable absentee votes to count in the second (general) election round if their first choice does not make the runoff. ], ], ] and ] adopt this approach.<ref>{{cite web|url=http://www.electionline.org/Portals/1/Publications/SC.EAP.2006primary.pdf |title=Initiatives – Pew Center on the States |publisher=Electionline.org |date= |accessdate=6 May 2010}}</ref><ref>{{Dead link|date=May 2010}}: ''E. Special Absentee Ballot for General Election: The special ballot permits you to vote in the following general election by writing in numbers according to your choice of preference for each candidate. You put the number one next to the name of the candidate who is your first choice, the number two for your second choice, and so forth so that, in consecutive numerical order, you write a number indicating your preference next to each candidate’s name on the ballot.''</ref> | |||
* IRV can quickly eliminate weak candidates in early rounds of an ] runoff, using rules to leave the desired number of candidates for further balloting. | |||
* IRV allows an arbitrary victory threshold in a single round of voting, e.g., 60%. In such cases a second vote may be held to confirm the winner.<ref>For example, in 2006, the ] used IRV for its endorsement elections, requiring 60% to win, and ''exhaustive balloting'' to follow if needed.</ref> | |||
* IRV elections that require a majority of cast ballots but not that voters rank all candidates may require more than a single IRV ballot due to exhausted ballots. | |||
* Robert's Rules recommends ] for elections by mail and requiring a majority of cast votes to elect a winner, giving IRV as their example. For in-person elections, they recommend repeated balloting until one candidate receives an absolute majority of all votes cast. Repeated voting allows voters to turn to a candidate as a compromise who polled poorly in the initial election.<ref name="autogenerated1"/> | |||
The common feature of these IRV variations is the one vote is counted per ballot per round, with rules that eliminate the weakest candidate(s) in successive rounds. Most IRV implementations drop the "] of cast ballots" requirement.<ref> Sec. 7. (6) ... if neither of the last two remaining candidates in an election ... received a majority, the report and the tabulations performed by the instant runoff count committee shall be forwarded to the Washington superior court, which shall issue a certificate of election to whichever of the two remaining candidates received the greatest number of votes at the conclusion of the instant runoff tabulation, and send a certified copy of the tabulation and results to the secretary of state.</ref> | |||
==See also== | |||
*] or Alternative Vote Top-up proposed by the ] | |||
*] | |||
*] (NOTA) or ] (RON) | |||
*] | |||
==References== | ==References== | ||
{{Reflist |
{{Reflist}} | ||
==External links== | ==External links== | ||
* by MIT Election Science Lab | |||
* 2010 articles from the and summarizing the proposed change in the United Kingdom to IRV/Alternative Vote | |||
;IRV in practice | |||
* from the Electoral Design Reference Materials | |||
* from | |||
* | |||
* from Australian Politics.com | |||
* | |||
* | |||
* | |||
* | |||
{{voting methods}} | |||
;Demos and simulations | |||
{{Parliament of Australia}} | |||
* A ranked choice ballot tool from the Indaba Application Network, including the animated display of an instant runoff. | |||
* | |||
* | |||
* | |||
* – 2-dimensional plots of results of various systems, with assumptions of sincere voting behavior. | |||
* Opposition article by Brian Olson. | |||
;Advocacy groups and positions | |||
* campaign site for the Yes side of the 2011 UK electoral reform referendum | |||
* at ] | |||
* | |||
* | |||
* | |||
* | |||
* | |||
* | |||
* | |||
* | |||
* | |||
;Opposition groups and positions | |||
* Anti-AV Referendum Site for the 2011 UK electoral reform referendum | |||
* campaign site for the No side of the 2011 UK electoral reform referendum | |||
* on the Alternative Vote | |||
* at the ] | |||
* Values and Risks Report by the N.C. Coalition for Verified Voting | |||
{{voting systems}} | |||
{{United Kingdom Alternative Vote referendum, 2011}} | {{United Kingdom Alternative Vote referendum, 2011}} | ||
{{DEFAULTSORT:Instant-Runoff Voting}} | |||
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Latest revision as of 07:20, 6 January 2025
Single-winner ranked-choice electoral system For the proportional electoral system applying ranked ballots to multi-member constituencies, see Single transferable vote. For ranked methods in general, see Ranked voting.
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Single-winner methodsSingle vote - plurality methods
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Instant-runoff voting (IRV; US: ranked-choice voting (RCV), AU: preferential voting, UK/NZ: alternative vote) is a single-winner, multi-round elimination rule that uses ranked voting to simulate a series of runoff elections. In each round, the candidate with the fewest first-preferences (among the remaining candidates) is eliminated. This continues until only one candidate is left. Instant runoff falls under the plurality-with-elimination family of voting methods, and is thus closely related to rules like the two-round runoff system.
IRV has found some use in national elections in several countries, predominantly in the Anglosphere. It is used to elect members of the Australian House of Representatives and the National Parliament of Papua New Guinea, and to elect the head of state in India, Ireland, and Sri Lanka.
The rule was first studied by the Marquis de Condorcet, who observed it could eliminate the majority-preferred candidate (Condorcet winner). Since then, IRV has been criticized for other mathematical pathologies (discussed below), including its ability to eliminate candidates for having too much support or too many votes. Like plurality, IRV also exhibits a kind of spoiler effect called a center squeeze, which causes it to favor uncompromising alternatives over more-moderate ones.
Advocates of IRV often argue these properties are positive, as voting rules should encourage candidates to appeal to their core support or political base rather than a broad coalition. They also note that in countries like the UK without primaries or runoffs, IRV can prevent spoiler effects by eliminating minor-party candidates. Unlike a straight plurality vote, IRV also avoids some kinds of vote-splitting by near-identical (clone) candidates.
Election procedure
In instant-runoff voting, as with other ranked voting rules, each voter orders candidates from first to last. The counting procedure is then as follows:
- If there is a candidate that has a majority of the top preferences of the valid, active ballots, then that candidate is elected and the count stops. If not, go to step 2.
- If there is more than one candidate left, eliminate the one with the fewest top preferences.
It is possible for a candidate to win an instant-runoff race without any support from more than half of voters, even when there is an alternative majority-approved candidate; this occurs when some voters truncate their ballots to show they do not support any candidates in the final round. In practice, candidates who do not receive a majority of votes in the first round usually do not finish with a majority.
Properties
Wasted votes and Condorcet winners
Compared to a plurality voting system that rewards only the top vote-getter, instant-runoff voting mitigates the problem of wasted votes. However, it does not ensure the election of a Condorcet winner, which is the candidate who would win a direct election against any other candidate in the race.
Invalid, incomplete and exhausted ballots
All forms of ranked-choice voting reduce to plurality when all ballots rank only one candidate. By extension, ballots for which all candidates ranked are eliminated are equivalent to votes for any non-winner in plurality, and considered exhausted ballots.
Some political scientists have found the system contributes to higher rates of spoiled votes, partly because the ballot marking is more complex. Most jurisdictions with IRV do not require complete rankings and may use columns to indicate preference instead of numbers. In American elections with IRV, more than 99 percent of voters typically cast a valid ballot.
A 2015 study of four local US elections that used IRV found that inactive ballots occurred often enough in each of them that the winner of each election did not receive a majority of votes cast in the first round. The rate of inactive ballots in each election ranged from a low of 9.6 percent to a high of 27.1 percent.
Resistance to strategy
Instant-runoff voting has notably high resistance to tactical voting but less to strategic nomination.
Party strategizing and strategic nomination
In Australia, preference deals (where one party's voters agree to place another party's voters second, in return for their doing the same) between parties are common. Parties and candidates often encourage their supporters to participate in these preference deals using How-to-vote cards explaining how to use their lower rankings to maximize the chances of their ballot helping to elect someone in the preference deal before it may exhaust.
Instant runoff may be manipulable via strategic candidate entry and exit, reducing similar candidates' chances of winning. Such manipulation does not need to be intentional, instead acting to deter candidates from running in the first place. Spatial model simulations indicate that instant runoff rewards strategic withdrawal by candidates.
Tactical voting
See also: Tactical voting § Instant runoff votingGibbard's theorem demonstrates that no (deterministic, non-dictatorial) voting method can be entirely immune from tactical voting. This implies that IRV is susceptible to tactical voting in some circumstances. In particular, when there exists a Condorcet winner who IRV fails to elect, voters who prefer the Condorcet winner to the IRV winner have an incentive to use the compromising strategy. IRV is also sometimes vulnerable to a paradoxical strategy of ranking a candidate higher to make them lose, due to IRV failing the monotonicity criterion.
Research suggests that IRV is very resistant to tactical voting. In a test of multiple methods, instant runoff was found to be the second-most-resistant to tactical voting, after a class of instant runoff-Condorcet hybrids. IRV is also completely immune to the burying strategy: ranking a strong opposition candidate lower can't get one's preferred candidate elected.
Tactical voting in IRV seeks to alter the order of eliminations in early rounds, to ensure that the original winner is challenged by a stronger opponent in the final round. For example, in a three-party election where voters for both the left and right prefer the centrist candidate to stop the opposing candidate from winning, those voters who care more about defeating the opposition than electing their own candidate may cast a tactical first-preference vote for the centrist candidate.
Spoiler effect
Main article: Spoiler effectProponents of IRV claim that IRV eliminates the spoiler effect, since IRV makes it safe to vote honestly for marginal parties. Under a plurality method, voters who sympathize most strongly with a marginal candidate are strongly encouraged to instead vote for a more popular candidate who shares some of the same principles, since that candidate has a much greater chance of being elected and a vote for the marginal candidate will not result in the marginal candidate's election. An IRV method reduces this problem, since the voter can rank the marginal candidate first and the mainstream candidate second; in the likely event that the fringe candidate is eliminated, the vote is not wasted but is transferred to the second preference.
However, when the third-party candidate is more competitive, they can still act as a spoiler under IRV, by taking away first-choice votes from the more mainstream candidate until that candidate is eliminated, and then that candidate's second-choice votes helping a more-disliked candidate to win. In these scenarios, it would have been better for the third party voters if their candidate had not run at all (spoiler effect), or if they had voted dishonestly, ranking their favourite second rather than first (favorite betrayal). This is the same bracketing effect exploited by Robinette and Tideman in their research on strategic campaigning, where a candidate alters their campaign to cause a change in voter honest choice, resulting in the elimination of a candidate who nevertheless remains more preferred by voters.
For example, in the 2009 Burlington, Vermont, mayoral election, if the Republican candidate who lost in the final instant runoff had not run, the Democratic candidate would have defeated the winning Progressive candidate. In that sense, the Republican candidate was a spoiler—albeit for an opposing Democrat, rather than some political ally—even though leading in first choice support. This also occurred in the 2022 Alaska's at-large congressional district special election. If Republican Sarah Palin, who lost in the final instant runoff, had not run, the more centrist Republican candidate, Nick Begich, would have defeated the winning Democratic candidate, Mary Peltola.
Reception
The system has had a mixed reception among political scientists and social choice theorists. Some have suggested that the system does not do much to decrease the impact of wasted votes relative to plurality. Research has found IRV causes lower confidence in elections and does not substantially affect minority representation, voter turnout, or long-run electoral competition. Opponents have also noted a high rate of repeals for the system.
Voter confusion and legitimacy
Governor Paul LePage and Representative Bruce Poliquin claimed, ahead of the 2018 primary elections, that IRV would result in "one person, five votes", as opposed to "one person, one vote". Federal judge Lance Walker rejected these claims, and the 1st circuit court denied Poliquin's emergency appeal.
Similarity to plurality
Often instant-runoff voting elections are won by the candidate who leads in first-count vote tallies so they choose the same winner as first-past-the-post voting would have. In Australia federal elections, the 1972 election had the largest number of winners who would not have won under first past the post but still only 14 out of 125 seats filled were not won by the first-count leader.
Participation
The effect of IRV on voter turnout is difficult to assess. In a 2021 report, researchers at New America, a think tank based in Washington, D. C., said it may increase turnout by attracting more and more diverse candidates, but the impact would be realized most significantly by getting rid of the need for primaries. The overall impact on diversity of candidates is difficult to detect.
Terminology
While instant run-off voting is distinguished from its multiple winner equivalent, the single transferable vote, in most English-speaking discussion of electoral systems, no distinction between the two is made in Ireland, one of the few countries to use these systems in all elections, either by the general population or in legal texts. The Constitution of Ireland describes the electoral system as "proportional representation by means of the single transferable vote", as do all other statutory authorities, when referring to either single-winner or multiple-winner elections. The acronym "PR-STV" is in general use to describe both types of elections. Examples of single-winner elections in Ireland which are described officially as "proportional representation by means of the single transferable vote" are the election of the President and the election of the Ceann Comhairle (chairperson of Dáil Éireann). The lack of distinction between the systems in Ireland reflects that there is no difference in the mechanics of the process from election to election, only the number of candidates to be elected by that process. This is not always the case when discussing the systems in the abstract, as there are many variations in how such elections could be run.
Instant-runoff voting derives its name from the way the ballot count simulates a series of runoffs, similar to an exhaustive ballot system, except that voters do not need to turn out several times to vote. It is also known as the alternative vote, transferable vote, ranked-choice voting (RCV), single-seat ranked-choice voting, or preferential voting (but use of some of those terms may lead to misunderstanding as they also apply to STV.)
Britons and New Zealanders generally call IRV the "alternative vote" (AV). Australians, who use IRV for most single winner elections, call IRV "preferential voting". While this term is widely used by Australians, it is somewhat of a misnomer. Depending on how "preferential" is defined, the term would include all voting systems, apply to any system that uses ranked ballots (thus both IRV and STV), or would exclude IRV (IRV fails positive responsiveness because ballot markings are not interpreted as "preferences" in the traditional sense. Under IRV (and STV), secondary preferences are used as back-up preferences/contingency votes).
Jurisdictions in the United States such as San Francisco, Minneapolis, Maine, and Alaska have tended to use the term "ranked-choice voting" in their laws that apply to IRV contests. The San Francisco Department of Elections claimed the word "instant" in the term "instant-runoff voting" could confuse voters into expecting results to be immediately available. As a result of American influence, the term ranked-choice voting is often used in Canada as well. American NGO FairVote has promoted the terminology "ranked-choice voting" to refer to IRV, a choice that has caused controversy and accusations that the organization is attempting to obscure the existence of other ranked-choice methods that could compete with IRV.
IRV is occasionally referred to as Hare's method (after Thomas Hare) to differentiate it from other ranked-choice voting methods such as majority-choice voting, Borda, and Bucklin, which use weighted preferences or methods that allow voter's lower preference to be used against voter's most-preferred choice.
When the single transferable vote (STV) method is applied to a single-winner election, it becomes IRV; the government of Ireland has called IRV "proportional representation" based on the fact that the same ballot form is used to elect its president by IRV and parliamentary seats by proportional representation (STV), but IRV is a non-proportional winner-take-all (single-winner) election method, while STV elects multiple winners.
State law in South Carolina and Arkansas use "instant runoff" to describe the practice of having certain categories of absentee voters cast ranked-choice ballots before the first round of an election and counting those ballots in any subsequent runoff elections.
History and use
Main article: History and use of instant-runoff votingHistory
This method was first discussed by the Marquis de Condorcet in 1788, who quickly rejected it after showing it would often eliminate a candidate preferred by a majority of voters.
IRV was later independently reinvented by Thomas Hare (of England) and Carl Andrae (of Denmark) in the form of the single transferable vote. Henry Richmond Droop then proposed applying the system to single-winner contests. (He also invented the Droop quota, which equates to a simple majority in a single-winner contest.)
Global use
Main article: History and use of instant-runoff voting § Use by countryNational level elections
Country | Body or office | Type of body or office | Electoral system | Total seats | Notes |
---|---|---|---|---|---|
Australia | House of Representatives | Lower chamber of legislature | IRV | 151 | |
Ireland | President | Head of State | IRV | ||
Dáil Éireann | Lower chamber of legislature | Single transferable vote (STV), by-elections using IRV | 158 | ||
Papua New Guinea | National Parliament | Unicameral legislature | IRV | 109 | |
United States | President (via Electoral College) | Head of State and Government | Alaska and Maine use IRV to select the state's electoral college seat winner or winners. In Maine, 2 electors are allocated to the winner of the state vote plurality and the others (currently 2) are allocated by plurality in each congressional district. In Alaska, the winner gets all Electoral College electors of the state (as Alaska has only one at-large district, the effect is the same). | 7 EVs (out of 538) | |
House of Representatives | Lower chamber of legislature | IRV in Maine
Nonpartisan primary system with IRV in the second round (among top four candidates) in Alaska. |
3 (out of 435) | ||
Senate | Upper chamber of legislature | 4 (out of 100) |
Robert's Rules of Order
In the United States, the sequential elimination method used by IRV is described in Robert's Rules of Order Newly Revised as an example of ranked-choice voting that can be used to elect officers. Robert's Rules note that ranked-choice systems (including IRV) are an improvement on simple plurality but recommend against runoff-based rules because they often prevent the emergence of a consensus candidate with broad support. The book instead recommends repeated balloting until some candidate manages to win a majority of votes. Two other books on American parliamentary procedure, The Standard Code of Parliamentary Procedure and Riddick's Rules of Procedure, take a similar stance.
Similar methods
Runoff voting
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The term instant-runoff voting is derived from the name of a class of voting methods called runoff voting. In runoff voting voters do not rank candidates in order of preference on a single ballot. Instead a similar effect is achieved by using multiple rounds of voting. All multi-round runoff voting methods allow voters to change their preferences in each round, incorporating the results of the prior round to influence their decision, which is not possible in IRV.
The runoff method closest to IRV is the exhaustive ballot. In this method—familiar to fans of the television show American Idol—one candidate is eliminated after each round, and many rounds of voting are used, rather than just two. Because holding many rounds of voting on separate days is generally expensive, the exhaustive ballot is not used for large-scale, public elections.
A more practical form of runoff voting is the two-round system, which excludes all but the top-two candidates after the first round, rather than gradually eliminating candidates over a series of rounds. Eliminations can occur with or without allowing and applying preference votes to choose the final two candidates. A second round of voting or counting is only necessary if no candidate receives an overall majority of votes. This method is used in Mali, France and the Finnish and Slovenian presidential election.
Contingent vote
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The contingent vote, also known as "top-two IRV", is the same as IRV, except that if no candidate achieves a majority in the first round of counting, all but the two candidates with the most votes are eliminated, and the second preferences for those ballots are counted. As in IRV, there is only one round of voting.
Under a variant of contingent voting used in Sri Lanka, and formerly for the elections for Mayor of London in the United Kingdom, voters rank a specified maximum number of candidates. In London, the supplementary vote allowed voters to express first and second preferences only. Sri Lankan voters rank up to three candidates to elect the president of Sri Lanka.
While similar to "sequential-elimination" IRV, top-two can produce different results. Excluding more than one candidate after the first count might eliminate a candidate who would have won under sequential elimination IRV. Restricting voters to a maximum number of preferences is more likely to exhaust ballots if voters do not anticipate which candidates will finish in the top two. This can encourage voters to vote more tactically, by ranking at least one candidate they think is likely to win.
Conversely, a practical benefit of 'contingent voting' is expediency and confidence in the result with only two rounds.
Larger runoff process
IRV may also be part of a larger runoff process:
- Some jurisdictions that hold runoff elections allow absentee (only) voters to submit IRV ballots, because the interval between votes is too short for a second round of absentee voting. IRV ballots enable absentee votes to count in the second (general) election round if their first choice does not make the runoff. Arkansas, South Carolina and Springfield, Illinois adopt this approach. Louisiana uses it only for members of the United States Service or who reside overseas.
- IRV can quickly eliminate weak candidates in early rounds of an exhaustive ballot runoff, using rules to leave the desired number of candidates for further balloting.
- IRV elections that require a majority of cast ballots but not that voters rank all candidates may require more than a single IRV ballot due to exhausted ballots.
- Robert's Rules recommends preferential voting for elections by mail and requiring a majority of cast votes to elect a winner. For in-person elections, they recommend repeated balloting until one candidate receives an absolute majority of all votes cast; if candidates drop out as soon as it becomes clear they cannot win, this procedure will always elect a Condorcet winner. The use of repeated balloting allows voters to resolve Condorcet cycles by discussion and compromise, or by electing a consensus candidate who might have polled poorly in the initial election.
Comparison to first-past-the-post
In the Australian federal election in September 2013, 135 out of the 150 House of Representatives seats (or 90 percent) were won by the candidate who led on first preferences. The other 15 seats (10 percent) were won by the candidate who placed second on first preferences.
Variations
A number of IRV methods, varying as to ballot design and as to whether or not voters are obliged to provide a full list of preferences, are in use in different countries and local governments.
In an optional preferential voting system, voters can give a preference to as many candidates as they wish. They may make only a single choice, known as "bullet voting", and some jurisdictions accept a single box marked with an "X" (as opposed to a numeral "1") as valid for the first preference. This may result in exhausted ballots, where all of a voter's preferences are eliminated before a candidate is elected, such that the "majority" in the final round may only constitute a minority fraction of all ballots cast. Optional preferential voting is used for elections for the President of Ireland as well as some elections in New South Wales and Queensland.
In a full-preferential voting method, voters are required to mark a preference for every candidate standing. Ballots that do not contain a complete ordering of all candidates are in some jurisdictions considered spoilt or invalid, even if there are only two candidates standing. This can become burdensome in elections with many candidates and can lead to "donkey voting", in which some voters simply choose candidates at random or in top-to-bottom order, or a voter may order his or her preferred candidates and then fill in the remainder on a donkey basis. Full preferential voting is used for elections to the Australian federal parliament and for most state parliaments.
Other methods only allow marking preferences for a maximum of the voter's top three favourites, a form of partial preferential voting.
A version of instant-runoff voting applying to the ranking of parties was first proposed for elections in Germany in 2013 as spare vote.
Voting method criteria
Main article: Voting criteriaAs shown by Arrow, Gibbard, and others, it's usually impossible for a method to pass all of a number of seemingly reasonable properties, or criteria, at once. IRV is no exception: it passes some and fails others. The following criteria are satisfied and failed by IRV:
Satisfied criteria
Condorcet loser Criterion
The Condorcet loser criterion states that "if a candidate would lose a head-to-head competition against every other candidate, then that candidate must not win the overall election". IRV (like all voting methods with a final runoff round) meets this criterion, since the Condorcet loser cannot win a runoff.
Independence of clones criterion
The independence of clones criterion states that "the election outcome remains the same even if an identical candidate who is equally preferred decides to run". Advocates have noted that IRV meeting this criterion greatly reduces the impact of clones compared to FPTP.
Later-no-harm criterion
The later-no-harm criterion states that "if a voter alters the order of candidates lower in his/her preference (e.g. swapping the second and third preferences), then that does not affect the chances of the most preferred candidate being elected". Instant runoff satisfies this criterion.
Majority criterion
The majority criterion states that "if one candidate is preferred by an absolute majority of voters, then that candidate must win". Instant runoff also satisfies this criterion.
Mutual majority criterion
The mutual majority criterion states that "if an absolute majority of voters prefer every member of a group of candidates to every candidate not in that group, then one of the preferred group must win". Note that this is satisfied because when all but one candidate that a mutual majority prefer is eliminated, the votes of the majority all flow to the remaining candidate, in contrast to FPTP, where the majority would be treated as separate small groups. Instant runoff satisfies this criterion as well.
Resolvability criterion
The resolvability criterion states that "the probability of an exact tie must diminish as more votes are cast".
Failed criteria
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Condorcet winner criterion
The Condorcet winner criterion states that "if a candidate would win a head-to-head competition against every other candidate, then that candidate must win the overall election". It is incompatible with the later-no-harm criterion, so IRV does not meet this criterion.
IRV is more likely to elect the Condorcet winner than plurality voting and traditional runoff elections. The California cities of Oakland, San Francisco and San Leandro in 2010 provide an example; there were a total of four elections in which the plurality-voting leader in first-choice rankings was defeated, and in each case the IRV winner was the Condorcet winner, including a San Francisco election in which the IRV winner was in third place in first choice rankings.
A particularly notable Condorcet failure occurred in the 2009 Burlington mayoral election.
Independence of irrelevant alternatives
The independence of irrelevant alternatives criterion states that "the election outcome remains the same even if a candidate who cannot win decides to run." Instant-runoff voting violates this. In the general case, instant-runoff voting can be susceptible to strategic nomination: whether or not a candidate decides to run at all can affect the result even if the new candidate cannot themselves win. This is less likely to happen than under plurality, but much more likely than under the Minimax Condorcet method.
Monotonicity criterion
Further information: Monotonicity criterion § Instant-runoff voting and the two-round system are not monotonicThe monotonicity criterion says that a voter ranking a candidate higher on their ballot should not cause that candidate to lose and conversely, that a voter ranking a candidate lower on their ballot should not help that candidate win. The exact probability of a monotonicity failure depends on the circumstances, but with 3 major candidates, the probabilities range from 15 percent under the impartial culture model to 8.5 percent in the case of a strict left–right spectrum.
Participation criterion
The participation criterion says that candidates should not lose as a result of having "too many voters"—a set of ballots that all rank A>B should not switch the election winner from B to A. IRV fails this criterion. In his 1984 study, mathematician Depankar Ray found that in elections where IRV elects a different candidate from plurality, that there was an estimated 50 percent probability that some voters would have gotten a more preferable outcome if they had not participated.
Reversal symmetry criterion
The reversal symmetry criterion states that the first- and last-place candidates should switch places if every ballot is reversed. In other words, it should not matter whether voters rank candidates from best-to-worst and select the best candidate, or whether they rank them worst-to-best and then select the least-bad candidate.
IRV fails this criterion: it is possible to construct an election where reversing the order of every ballot does not alter the final winner; that is, the first- and last-place finishers, according to IRV, are the same candidate.
Comparison to other voting systems
Main article: Comparison of electoral systemsCriterion Method |
Majority winner | Majority loser | Mutual majority | Condorcet winner |
Condorcet loser | Smith |
Smith-IIA |
IIA/LIIA |
Cloneproof | Monotone | Participation | Later-no-harm |
Later-no-help |
No favorite betrayal |
Ballot
type | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
First-past-the-post voting | Yes | No | No | No | No | No | No | No | No | Yes | Yes | Yes | Yes | No | Single mark | |
Anti-plurality | No | Yes | No | No | No | No | No | No | No | Yes | Yes | No | No | Yes | Single mark | |
Two round system | Yes | Yes | No | No | Yes | No | No | No | No | No | No | Yes | Yes | No | Single mark | |
Instant-runoff | Yes | Yes | Yes | No | Yes | No | No | No | Yes | No | No | Yes | Yes | No | Ranking | |
Coombs | Yes | Yes | Yes | No | Yes | No | No | No | No | No | No | No | No | Yes | Ranking | |
Nanson | Yes | Yes | Yes | Yes | Yes | Yes | No | No | No | No | No | No | No | No | Ranking | |
Baldwin | Yes | Yes | Yes | Yes | Yes | Yes | No | No | No | No | No | No | No | No | Ranking | |
Tideman alternative | Yes | Yes | Yes | Yes | Yes | Yes | Yes | No | Yes | No | No | No | No | No | Ranking | |
Minimax | Yes | No | No | Yes |
No | No | No | No | No | Yes | No | No |
No | No | Ranking | |
Copeland | Yes | Yes | Yes | Yes | Yes | Yes | Yes | No | No | Yes | No | No | No | No | Ranking | |
Black | Yes | Yes | No | Yes | Yes | No | No | No | No | Yes | No | No | No | No | Ranking | |
Kemeny–Young | Yes | Yes | Yes | Yes | Yes | Yes | Yes | LIIA Only | No | Yes | No | No | No | No | Ranking | |
Ranked pairs | Yes | Yes | Yes | Yes | Yes | Yes | Yes | LIIA Only | Yes | Yes | No |
No | No | No | Ranking | |
Schulze | Yes | Yes | Yes | Yes | Yes | Yes | Yes | No | Yes | Yes | No |
No | No | No | Ranking | |
Borda | No | Yes | No | No | Yes | No | No | No | No | Yes | Yes | No | Yes | No | Ranking | |
Bucklin | Yes | Yes | Yes | No | No | No | No | No | No | Yes | No | No | Yes | No | Ranking | |
Approval | Yes | No | No | No | No | No | No | Yes |
Yes | Yes | Yes | No | Yes | Yes | Approvals | |
Majority Judgement | No | No |
No |
No | No | No | No | Yes |
Yes | Yes | No |
No | Yes | Yes | Scores | |
Score | No | No | No | No | No | No | No | Yes |
Yes | Yes | Yes | No | Yes | Yes | Scores | |
STAR | No | Yes | No | No | Yes | No | No | No | No | Yes | No | No | No | No | Scores | |
Quadratic | No | No | No | No | No | No | No | No | No | Yes | Yes | N/A | N/A | No | Credits | |
Random ballot |
No | No | No | No | No | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Single mark | |
Sortition |
No | No | No | No | No | No | No | Yes | No | Yes | Yes | Yes | Yes | Yes | None | |
Table Notes |
|
Examples
The first example is a fictional one for the purpose of demonstrating the principle of instant runoff. The other examples are drawn from the results of real-life elections.
Tennessee capital example
Suppose that Tennessee is holding an election on the location of its capital. The population is concentrated around four major cities. All voters want the capital to be as close to them as possible. The options are:
- Memphis, the largest city, but far from the others (42% of voters)
- Nashville, near the center of the state (26% of voters)
- Chattanooga, somewhat east (15% of voters)
- Knoxville, far to the northeast (17% of voters)
The preferences of each region's voters are:
42% of voters Far-West |
26% of voters Center |
15% of voters Center-East |
17% of voters Far-East |
---|---|---|---|
|
|
|
|
It takes three rounds to determine a winner in this election.
Round 1 – In the first round no city gets a majority:
Votes in round/
City Choice |
1st |
---|---|
Memphis | 42% |
Nashville | 26% |
Knoxville | 17% |
Chattanooga | 15% |
If one of the cities had achieved a majority vote (more than half), the election would end there. If this were a first-past-the-post election, Memphis would win because it received the most votes. But IRV does not allow a candidate to win on the first round without having an absolute majority of the active votes. Since no city has won yet, the city with the least first-place support (Chattanooga) is eliminated from consideration. The ballots that listed Chattanooga as first choice are added to the totals of the second-choice selection on each ballot.
Round 2 – In the second round of tabulation, Chattanooga's 15% of the total votes have been added to the second choices selected by the voters for whom that city was first-choice (in this example Knoxville):
Votes in round/
City Choice |
1st | 2nd |
---|---|---|
Memphis | 42% | 42% |
Nashville | 26% | 26% |
Knoxville | 17% | 32% |
Chattanooga | 15% |
In the first round, Memphis was first, Nashville was second and Knoxville was third. With Chattanooga eliminated and its votes redistributed, the second round finds Memphis still in first place, followed by Knoxville in second and Nashville has moved down to third place. No city yet has secured a majority of votes, so the now last placed Nashville is eliminated and the ballots currently counting for Nashville are added to the totals of Memphis or Knoxville based on which city is ranked next on that ballot.
Round 3
As Memphis and Knoxville are the only two cities remaining in the contest, this round will be the final round. In this example the second-choice of the Nashville voters is Chattanooga, which is already eliminated. Therefore, the votes are added to their third-choice: Knoxville. The third round of tabulation yields the following result:
Votes in round/
City Choice |
1st | 2nd | 3rd |
---|---|---|---|
Memphis | 42% | 42% | 42% |
Nashville | 26% | 26% | |
Knoxville | 17% | 32% | 58% |
Chattanooga | 15% |
Result: Knoxville, which was running third in the first tabulation, has moved up from behind to take first place in the third and final round. The winner of the election is Knoxville. However, if 6% of voters in Memphis were to put Nashville first, the winner would be Nashville, a preferable outcome for voters in Memphis. This is an example of potential tactical voting, though one that would be difficult for voters to carry out in practice. Also, if 17% of voters in Memphis were to stay away from voting, the winner would be Nashville. This is an example of IRV failing the participation criterion.
For comparison, note that traditional first-past-the-post voting would elect Memphis, even though most citizens consider it the worst choice, because 42% is larger than any other single city. As Nashville is a Condorcet winner, Condorcet methods would elect Nashville. A two-round method would have a runoff between Memphis and Nashville where Nashville would win, too.
1990 Irish presidential election
See also: Irish presidential election, 1990The 1990 Irish presidential election provides a simple example of how instant-runoff voting can produce a different result from first-past-the-post voting and prevent some spoiler effects associated with plurality voting. The three major candidates were Brian Lenihan of Fianna Fáil, Austin Currie of Fine Gael, and Mary Robinson of the Labour Party. After the first count, Lenihan had the largest share of first-choice rankings. Currie had the fewest votes and was eliminated. After this, Robinson received 82 percent of Currie's votes, thereby overtaking Lenihan.
Candidate | Round 1 | Round 2 | ||
---|---|---|---|---|
Mary Robinson | 612,265 | 38.9% | 817,830 | 51.6% |
Brian Lenihan | 694,484 | 43.8% | 731,273 | 46.2% |
Austin Currie | 267,902 | 16.9%N | Eliminated | |
Exhausted ballots | 9,444 | 0.6% | 34,992 | 2.2% |
Total | 1,584,095 | 100% | 1,584,095 | 100% |
2014 Prahran election (Victoria)
Another real-life example of IRV producing results different from first-past-the-post can be seen in the 2014 Victorian general election in Prahran. In this rare instance, the candidate who initially placed third, (Greens candidate Sam Hibbins), won the seat. In the 7th and final round, Hibbins narrowly defeated Liberal candidate Clem Newton-Brown by a margin of 277 votes.
Candidate | 1st | 2nd | 3rd | 4th | 5th | 6th | 7th | ||
---|---|---|---|---|---|---|---|---|---|
Clem Newton-Brown (LIB) | 44.8% | 16,582 | 16,592 | 16,644 | 16,726 | 16,843 | 17,076 | 18,363 | 49.6% |
Neil Pharaoh (ALP) | 25.9% | 9,586 | 9,593 | 9,639 | 9,690 | 9,758 | 9,948N | Eliminated | |
Sam Hibbins (GRN) | 24.8% | 9,160 | 9,171 | 9,218 | 9,310 | 9,403 | 9,979 | 18,640 | 50.4% |
Eleonora Gullone (AJP) | 2.3% | 837 | 860 | 891 | 928 | 999N | Eliminated | ||
Alan Walker (FFP) | 0.8% | 282 | 283 | 295N | Eliminated | ||||
Jason Goldsmith (IND) | 0.7% | 247 | 263 | 316 | 349N | Eliminated | |||
Steve Stefanopoulos (IND) | 0.6% | 227 | 241N | Eliminated | |||||
Alan Menadue (IND) | 0.2% | 82N | Eliminated | ||||||
Total | 100% | 37,003 |
2009 Burlington mayoral election
See also: 2009 Burlington mayoral electionCandidates | 1st round | 2nd round | 3rd round | ||||
---|---|---|---|---|---|---|---|
Candidate | Party | Votes | ± | Votes | ± | Votes | ± |
Bob Kiss | Progressive | 2585 | +2585 | 2981 | +396 | 4313 | +1332 |
Kurt Wright | Republican | 2951 | +2951 | 3294 | +343 | 4061 | +767 |
Andy Montroll | Democrat | 2063 | +2063 | 2554 | +491 | 0 | −2554 |
Dan Smith | Independent | 1306 | +1306 | 0 | −1306 | ||
Others | 71 | +71 | 0 | −71 | |||
Exhausted | 4 | +4 | 151 | +147 | 606 | +455 |
Under Burlington, Vermont's second-ever IRV mayoral election in 2009, the winner, Bob Kiss, was elected over the more popular Andy Montroll as a result of a first-round spoiler effect.
FairVote touted the 2009 election as one of its major success stories, claiming it helped the city save on costs of a traditional runoff and prevented a spoiler effect, although later analysis showed that without Wright in the election, Montroll would have defeated Kiss in a one-on-one race.
Mathematicians and voting theorists criticized the election results as revealing several pathologies associated with instant-runoff voting, noting that Kiss was elected as a result of 750 votes cast against him (ranking Kiss in last place).
Several electoral reform advocates branded the election a failure after Kiss was elected, despite 54 percent of voters voting for Montroll over Kiss, violating the principle of majority rule.
See also
- Single transferable vote, a proportional method that reduces to instant runoff in single-winner elections.
- Ranked voting
- Comparison of electoral systems
- Alternative vote plus (AV+), or alternative vote top-up, proposed by the Jenkins Commission in the UK
- Duverger's law
- Write-in candidate
Notes
- This procedure can be sped-up by eliminating more than one candidate if their combined top preferences are less than the next-lowest remaining candidate; this process is sometimes called batch elimination. When batch elimination is used, the procedure can terminate if some candidate has a majority.
- Figure 4 on page 137 shows instant-runoff voting having exit incentive despite being clone independent.
- Following the Elections Act 2022, voting in mayoral elections now takes place under the first-past-the-post system.
References
- Nurmi, Hannu (June 2005). "Aggregation problems in policy evaluation: an overview". European Journal of Political Economy. 21 (2): 287–300. doi:10.1016/j.ejpoleco.2004.08.001. ISSN 0176-2680.
- Aubin, Jean-Baptiste; Gannaz, Irène; Leoni-Aubin, Samuela; Rolland, Antoine (July 2024). A simulation-based study of proximity between voting rules.
- Hyman, Ross; Otis, Deb; Allen, Seamus; Dennis, Greg (1 September 2024). "A majority rule philosophy for instant runoff voting". Constitutional Political Economy. 35 (3): 425–436. arXiv:2308.08430. doi:10.1007/s10602-024-09442-3. ISSN 1572-9966.
- Condorcet, Jean-Antoine-Nicolas de Caritat (1788). "On the Constitution and the Functions of Provincial Assemblies". Complete Works of Condorcet (in French). Vol. 13 (published 1804). p. 243.
En effet, lorsqu'il y a plus de trois concurrents, le véritable vœu de la pluralité peut être pour un candidat qui n'ait eu aucune des voix dans le premier scrutin.
- Nanson, E. J. (1882). "Methods of election: Ware's Method". Transactions and Proceedings of the Royal Society of Victoria. 17: 206.
The method was, however, mentioned by Condorcet, but only to be condemned.
- Campbell, D.E.; Kelly, J.S. (2000). "A simple characterization of majority rule". Economic Theory. 15 (3): 689–700. doi:10.1007/s001990050318. JSTOR 25055296. S2CID 122290254.
- McGann, Anthony J.; Koetzle, William; Grofman, Bernard (2002). "How an Ideologically Concentrated Minority Can Trump a Dispersed Majority: Nonmedian Voter Results for Plurality, Run-off, and Sequential Elimination Elections". American Journal of Political Science. 46 (1): 134–147. doi:10.2307/3088418. ISSN 0092-5853. JSTOR 3088418.
As with simple plurality elections, it is apparent the outcome will be highly sensitive to the distribution of candidates.
- Doron, Gideon; Kronick, Richard (1977). "Single Transferrable Vote: An Example of a Perverse Social Choice Function". American Journal of Political Science. 21 (2): 303–311. doi:10.2307/2110496. ISSN 0092-5853. JSTOR 2110496.
- Nurmi, Hannu (December 1996). "It's not just the lack of monotonicity1". Representation. 34 (1): 48–52. doi:10.1080/00344899608522986. ISSN 0034-4893.
- Atkinson, Nathan; Ganz, Scott C. (30 October 2022). "The flaw in ranked-choice voting: rewarding extremists". The Hill. Retrieved 14 May 2023.
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 by a majority of voters to each of the more extreme candidates. 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.
- McGann, Anthony J.; Koetzle, William; Grofman, Bernard (2002). "How an Ideologically Concentrated Minority Can Trump a Dispersed Majority: Nonmedian Voter Results for Plurality, Run-off, and Sequential Elimination Elections". American Journal of Political Science. 46 (1): 134–147. doi:10.2307/3088418. ISSN 0092-5853. JSTOR 3088418.
As with simple plurality elections, it is apparent the outcome will be highly sensitive to the distribution of candidates.
- Merrill, Samuel (1985). "A statistical model for Condorcet efficiency based on simulation under spatial model assumptions". Public Choice. 47 (2): 389–403. doi:10.1007/bf00127534. ISSN 0048-5829.
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
- Merrill, Samuel (1984). "A Comparison of Efficiency of Multicandidate Electoral Systems". American Journal of Political Science. 28 (1): 23–48. doi:10.2307/2110786. ISSN 0092-5853. JSTOR 2110786.
However, squeezed by surrounding opponents, a centrist candidate may receive few first-place votes and be eliminated under Hare.
- Robinette, Robbie (1 September 2023). "Implications of strategic position choices by candidates". Constitutional Political Economy. 34 (3): 445–457. doi:10.1007/s10602-022-09378-6. ISSN 1572-9966.
- Hyman, Ross; Otis, Deb; Allen, Seamus; Dennis, Greg (September 2024). "A Majority Rule Philosophy for Instant Runoff Voting". Constitutional Political Economy. 35 (3): 425–436. arXiv:2308.08430. doi:10.1007/s10602-024-09442-3. ISSN 1043-4062.
- Dopp, Kathy Anne (2011). "Realities Mar Instant Runoff Voting Flaws and Benefits of IRV". SSRN 1858374.
- ^ Graham-Squire, Adam; McCune, David (6 March 2023). "An Examination of Ranked Choice Voting in the United States, 2004-2022". arXiv:2301.12075 .
- Chamberlin, John R.; Cohen, Michael D. (1978). "Toward Applicable Social Choice Theory: A Comparison of Social Choice Functions under Spatial Model Assumptions". American Political Science Review. 72 (4). Cambridge University Press (CUP): 1341–1356. doi:10.2307/1954543. ISSN 0003-0554. JSTOR 1954543.
A long-established response to the 'wasted vote' problem is the method advocated by Hare...
- ^ Pettigrew, Stephen; Radley, Dylan (2023). "Ballot Marking Errors in Ranked-Choice Voting". SSRN 4670677.
- "Instant Runoff Voting and Its Impact on Racial Minorities" (PDF). New America Foundation. 1 August 2008. Archived from the original (PDF) on 15 June 2011. Retrieved 15 August 2011.
- Burnett, Craig M.; Kogan, Vladimir (March 2015). "Ballot (and voter) 'exhaustion' under Instant Runoff Voting: An examination of four ranked-choice elections". Electoral Studies. 37: 41–49. doi:10.1016/j.electstud.2014.11.006. S2CID 11159132.
- "Explained: What are 'preference deals' and how do they influence my vote?". 9News. 20 May 2022.
- Robinette, Robbie (2 February 2023). "Implications of strategic position choices by candidates". Constitutional Political Economy. 34 (3). Springer Science and Business Media LLC: 445–457. doi:10.1007/s10602-022-09378-6. ISSN 1043-4062.
- ^ Green-Armytage, James (2014). "Strategic voting and nomination". Social Choice and Welfare. 42 (1). Springer: 111–138. doi:10.1007/s00355-013-0725-3. ISSN 0176-1714. JSTOR 43663746. S2CID 253847024. Retrieved 23 February 2024.
- "Monotonicity and IRV – Why the Monotonicity Criterion is of Little Import". archive.fairvote.org. Retrieved 17 April 2011.
- Green-Armytage, James (2011). "Four Condorcet-Hare Hybrid Methods for Single-Winner Elections" (PDF). Voting matters. Retrieved 25 October 2024.
- Borgers, Christoph (2010). Mathematics of Social Choice: Voting, Compensation, and Division. SIAM. ISBN 9780898716955.
Candidates C and D spoiled the election for B ... With them in the running, A won, whereas without them in the running, B would have won. ... Instant runoff voting ... does not do away with the spoiler problem entirely, although it ... makes it less likely
- Poundstone, William (2009). Gaming the Vote: Why Elections Aren't Fair (and What We Can Do About It). Farrar, Straus and Giroux. ISBN 9781429957649.
IRV is excellent for preventing classic spoilers-minor candidates who irrationally tip the election from one major candidate to another. It is not so good when the 'spoiler' has a real chance of winning
- ^ Bristow-Johnson, R. (2023). "The failure of Instant Runoff to accomplish the purpose for which it was adopted: a case study from Burlington Vermont" (PDF). Const Polit Econ. 34 (3): 378–389. doi:10.1007/s10602-023-09393-1. S2CID 255657135. Retrieved 9 January 2024.
- O'Neill, Jeffrey C. (2006). "Everything That Can be Counted Does Not Necessarily Count: The Right to Vote and the Choice of a Voting System". p. 340. SSRN 883058.
With instant runoff voting ... The strategy for the liberal voter is the same as for plurality voting: Her favorite candidate cannot win, so she casts her vote for her favorite candidate with a realistic chance of winning
- Graham-Squire, Adam; McCune, David (2022). "A Mathematical Analysis of the 2022 Alaska Special Election for US House". arXiv:2209.04764v1 .
- ^ Drutman, Lee; Strano, Maresa (10 November 2021). "What We Know About Ranked-Choice Voting". New America. Retrieved 28 February 2023.
- Drutman, Lee (18 September 2023). "How I updated my views on ranked choice voting". Undercurrent Events. Retrieved 2 September 2024.
- "Understanding the Limited Preferential Voting system – EMTV Online". 10 April 2017. Retrieved 18 February 2021.
- ^ Endersby, James W.; Towle, Michael J. (1 March 2014). "Making wasted votes count: Turnout, transfers, and preferential voting in practice". Electoral Studies. 33: 144–152. doi:10.1016/j.electstud.2013.07.001. ISSN 0261-3794.
- "The Effect of Ranked-Choice Voting in Maine | MIT Election Lab". electionlab.mit.edu. Retrieved 2 September 2024.
- ^ Cerrone, Joseph; McClintock, Cynthia (August 2023). "Come-from-behind victories under ranked-choice voting and runoff: The impact on voter satisfaction". Politics & Policy. 51 (4): 569–587. doi:10.1111/polp.12544. ISSN 1555-5623.
- Nielson, Lindsay (August 2017). "Ranked Choice Voting and Attitudes toward Democracy in the United States: Results from a Survey Experiment". Politics & Policy. 45 (4): 535–570. doi:10.1111/polp.12212. ISSN 1555-5623.
- ^ "The Short-Term Impact of Ranked-Choice Voting on Candidate Entry and Descriptive Representation". New America. Retrieved 2 September 2024.
- Leary, Mal (12 June 2018). "Opposed To Ranked-Choice Voting, LePage Says He Might Not Certify Primary Election Results". Maine Public. Retrieved 14 January 2019.
- "Complaint" (PDF), Baber v. Dunlap (Court Filing), no. 1:18-cv-00465, Docket 1, D.M.E., 13 November 2018, retrieved 13 January 2019 – via Recap
- "1st Circuit ends Poliquin's efforts to keep House seat". Bangor Daily News. 22 December 2018. Retrieved 17 August 2019.
- Green, Antony (11 May 2010). "Preferential Voting in Australia". www.abc.net.au. Retrieved 1 November 2020.
- "What We Know About Ranked-Choice Voting". New America.
- ref name="Articles 16.2.5°, 12.2.3°, and 18.5, Constitution of Ireland">"Constitution of Ireland (English)". Office of the Attourney General. January 2020. Retrieved 19 December 2024.
- "Second Report: Election of a Speaker". House of Commons Select Committee on Procedure. 15 February 2001. Retrieved 18 February 2008.
- Cary, David (1 January 2011). "Estimating the Margin of Victory for Instant-runoff Voting". Proceedings of the 2011 Conference on Electronic Voting Technology/Workshop on Trustworthy Elections. EVT/WOTE'11: 3.
- "BBC News – Alternative vote". bbc.com. British Broadcasting Corporation. 8 February 2012. Retrieved 9 October 2019.
- "Opinion: OUSA Needs the Alternative Vote". Critic – Te Arohi. Otago, New Zealand: Otago University Students' Association. 30 September 2017. Retrieved 9 October 2019.
- "Liberal plan to change federal voting laws may have crossbench support". The Guardian. 11 December 2020. Retrieved 13 February 2021.
- Appendix D, Instant Runoff Voting, San Francisco Charter § 13.102 https://sfgov.org/ccsfgsa/sites/default/files/Voting%20Systems%20Task%20Force/AppendixD__.pdf.
- Arntz, John (2 February 2005). "Ranked-Choice Voting: A Guide for Candidates" (PDF). Department of Elections: City and County of San Francisco. Archived from the original (PDF) on 2 December 2008. Retrieved 25 August 2009 – via FairVote.
In San Francisco, ranked-choice voting is sometimes called 'instant run-off voting.' The Department of Elections generally uses the term ranked-choice voting, because it describes the voting method—voters are directed to rank their first-, second- and third-choice candidates. The Department also uses the term ranked-choice voting because the word 'instant' might create an expectation that final results will be available immediately after the polls close on election night.
- ^ "What is Ranked Choice Voting?". City of London. Archived from the original on 26 February 2018.
- "How RCV Works". FairVote. 17 August 2019. Retrieved 17 August 2018.
- Pacuit, Eric (24 June 2019) . "Voting Methods". In Zalta, Edward N. (ed.). The Stanford Encyclopedia of Philosophy (Fall 2019 ed.) – via plato.stanford.edu.
- "Proportional Representation". Citizens Information Board. Retrieved 17 August 2019.
- "South Carolina General Assembly : 116th Session, 2005–2006". Scstatehouse.gov. Retrieved 1 March 2015.
- "Bill Information". Arkleg.state.ar.us. Retrieved 28 January 2015.
- Nanson, E. J. (1882). "Methods of election: Ware's Method". Transactions and Proceedings of the Royal Society of Victoria. 17: 206.
The method was, however, mentioned by Condorcet, but only to be condemned.
- Condorcet, Jean-Antoine-Nicolas de Caritat (1788). "On the Constitution and the Functions of Provincial Assemblies". Complete Works of Condorcet (in French). Vol. 13 (published 1804). p. 243.
En effet, lorsqu'il y a plus de trois concurrents, le véritable vœu de la pluralité peut être pour un candidat qui n'ait eu aucune des voix dans le premier scrutin.
- The Ceann Comhairle or Speaker of Dáil Éireann is returned automatically for whichever constituency s/he was elected if they wish to seek re-election, reducing the number of seats contested in that constituency by one. (In that case, should the Ceann Comhairle be from a three-seater, only two seats are contested in the general election from there.) As a result, if the Ceann Comhairle wishes to be in the next Dáil, only 165 seats are actually contested in a general election.
- electoral votes
- "Maine became the first state in the country Tuesday to pass ranked-choice voting". 10 November 2016. Retrieved 10 November 2016.
- "Ranked Choice Voting | Maine Voters Rank Candidates". Maine Uses Ranked Choice Voting. Archived from the original on 4 April 2018. Retrieved 8 April 2018.
- Russell, Eric (12 June 2018). "Mainers vote to keep ranked-choice voting, with supporters holding commanding lead". Portland Press Herald. Retrieved 13 June 2018.
- "Alaska Ballot Measure 2, Top-Four Ranked-Choice Voting and Campaign Finance Laws Initiative (2020)". Ballotpedia. Retrieved 17 November 2020.
- ^ Robert, Henry (2011). Robert's Rules of Order Newly Revised (11th ed.). Da Capo Press. pp. 425–428. ISBN 978-0-306-82020-5.
- Sturgis, Alice (2001). The Standard Code of Parliamentary Procedure, 4th ed.
- Riddick & Butcher (1985). Riddick's Rules of Procedure, 1985 ed.
- "Initiatives – Pew Center on the States" (PDF). Electionline.org. Archived from the original (PDF) on 16 May 2008. Retrieved 6 May 2010.
- IRV for Louisiana's Overseas Voters (web page), FairVote IRV America, retrieved 16 June 2013
- Antony Green (8 September 2015). Preferences, Donkey Votes and the Canning By-Election – Antony Green's Election Blog (Australian Broadcasting Corporation). Retrieved 8 September 2015.
- "Voting system". www.ecq.qld.gov.au. Electoral Commission of Queensland. 28 January 2020. Retrieved 17 November 2020.
- Stevens, Bronwyn (27 January 2015). "Are Queenslanders in danger of 'wasting' their votes?". The Conversation. Retrieved 28 November 2020.
- "Electoral Systems". Electoral Council of Australia. Archived from the original on 9 March 2008. Retrieved 15 February 2008.
- "Ranked-Choice Voting". Registrar of Voters, Alameda County. Retrieved 15 December 2016.
This format allows a voter to select a first-choice candidate in the first column, a second-choice candidate in the second column, and a third-choice candidate in the third column.
- Breyer, Patrick (November 2013). "Alternative II: Einführung einer Ersatzstimme" (PDF). Anhörung zum Entwurf eines Gesetzes zur Abschaffung der Fünf-Prozent-Sperrklausel bei Landtagswahlen in Schleswig-Holstein [Hearing on the draft law to abolish the five percent threshold in state elections in Schleswig-Holstein (Discussion paper)] (Report) (in German). Piratenfraktion im Schleswig-Holsteinischen Landtag. (Drs. 18/385).
- Green-Armytage, James (2004). "A Survey of Basic Voting Methods". Archived from the original on 3 June 2013.
- Tideman, T. N. (1987). "Independence of clones as a criterion for voting rules". Social Choice and Welfare. 4 (3). Springer Science and Business Media LLC: 185–206. doi:10.1007/bf00433944. ISSN 0176-1714.
Among previously proposed voting rules, the alternative vote and the GOCHA rule are independent of clones.
- Miller, Nicholas R. (2012). "Monotonicity failure in IRV elections with three candidates". World meeting of the public choice societies.
- Lepelley, Dominique; Chantreuil, Frederic; Berg, Sven (1996). "The likelihood of monotonicity paradoxes in run-off elections". Mathematical Social Sciences. 31 (3): 133–146. doi:10.1016/0165-4896(95)00804-7.
- Ray, Depankar (1986). "On the practical possibility of a 'no show paradox' under the single transferable vote". Mathematical Social Sciences. 11 (2): 183–189. doi:10.1016/0165-4896(86)90024-7.
- Felsenthal, Dan S. (2012). "Review of Paradoxes Afflicting Procedures for Electing a Single Candidate". In Felsenthal, Dan S.; Machover, Moshé (eds.). Electoral Systems. Studies in Choice and Welfare. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 19–91 . doi:10.1007/978-3-642-20441-8_3. ISBN 978-3-642-20440-1. Retrieved 8 November 2024.
- "Presidential Election November 1990". ElectionsIreland.org. Retrieved 23 November 2009.
- "State Election 2014: Prahran District (Distribution of preference votes)". Victorian Electoral Commission. Archived from the original on 25 July 2018. Retrieved 25 July 2018.
- ^ Etnier, Carl (6 March 2009). "Instant runoff was success". Rutland Herald. Retrieved 17 March 2018.
- Totten, Shay. "Burlington Residents Seek Repeal of Instant Runoff Voting". Seven Days. Retrieved 17 March 2018.
We waited to bring in the signatures because we didn't want this to be about Kurt Wright losing after being ahead, or Andy Montroll who had more first and second place votes and didn't win. We wanted this to be about IRV.
- Bouricius, Terry (17 March 2009). "Response to Faulty Analysis of Burlington IRV Election". FairVote.org. Retrieved 1 October 2017.
successfully prevented the election of the candidate who would likely have won under plurality rules, but would have lost to either of the other top finishers in a runoff
- ^ Lewyn, Michael (2012). "Two Cheers for Instant Runoff Voting". Phoenix L. Rev. 6: 117. SSRN 2276015.
election where Democratic candidate for mayor was Condorcet winner but finished third behind Republican and 'Progressive'
- Felsenthal, Dan S.; Tideman, Nicolaus (2014). "Interacting double monotonicity failure with direction of impact under five voting methods". Mathematical Social Sciences. 67: 57–66. doi:10.1016/j.mathsocsci.2013.08.001. ISSN 0165-4896.
A display of non-monotonicity under the Alternative Vote method was reported recently, for the March 2009 mayoral election in Burlington, Vermont.
- Ornstein, Joseph T.; Norman, Robert Z. (1 October 2014). "Frequency of monotonicity failure under Instant Runoff Voting: estimates based on a spatial model of elections". Public Choice. 161 (1–2): 1–9. doi:10.1007/s11127-013-0118-2. ISSN 0048-5829. S2CID 30833409.
Although the Democrat was the Condorcet winner (a majority of voters preferred him in all two way contests), he received the fewest first-place votes and so was eliminated ... 2009 mayoral election in Burlington, VT, which illustrates the key features of an upward monotonicity failure
- Bristow-Johnson, Robert (2023). "The failure of Instant Runoff to accomplish the purpose for which it was adopted: a case study from Burlington Vermont". Constitutional Political Economy. 34 (3): 378–389. doi:10.1007/s10602-023-09393-1.
- Ellenberg, Jordan (29 May 2014). How Not to Be Wrong: The Power of Mathematical Thinking. Penguin. p. 385. ISBN 9780698163843.
a majority of voters liked the centrist candidate Montroll better than Kiss, and a majority of voters liked Montroll better than Wright ... yet Montroll was tossed in the first round.
- Stensholt, Eivind (7 October 2015). "What Happened in Burlington?". SSRN 2670462.
K was elected even though M was a clear Condorcet winner and W was a clear Plurality winner.
- Dopp, Kathy (10 June 2009). "IRV much worse than old runoffs". The Aspen Times. Retrieved 17 March 2018.
External links
- "Explainer: Instant runoff voting" by MIT Election Science Lab
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