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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}}{{Use dmy dates|date=April 2024}}{{Use American English|date=May 2024}}{{Undisclosed paid|date=May 2024}}{{Electoral systems}}Instant-runoff voting (IRV), also known as plurality with elimination or plurality loser,WEB, Koether, Robb T., The Plurality-with-Elimination Method,people.hsc.edu/faculty-staff/robbk/Math111/Lectures/Fall%202017/Lecture%209%20-%20The%20Plurality-with-Elimination%20Method.pdf#:~:text=By%20the%20plurality-with-elimination%20method%20%28also%20called%20instant-runoff%20voting%2C,the%20remaining%20candidates%20until%20there%20is%20a%20winner., is a ranked-choice voting system that modifies plurality by repeatedly eliminating the last-place finisher until only one candidate is left.BOOK, Robert, Henry, Robert’s Rules of Order Newly Revised, Da Capo Press, 2011, 978-0-306-82020-5, 11th, 425–428, WEB, 8 April 2005, Types of Voting Systems,www.mtholyoke.edu/acad/polit/damy/BeginnningReading/types.htm, 6 May 2010, Mtholyoke.edu, 8 July 2006,www.mtholyoke.edu/acad/polit/damy/BeginnningReading/types.htm," title="web.archive.org/web/20060708090550www.mtholyoke.edu/acad/polit/damy/BeginnningReading/types.htm,">web.archive.org/web/20060708090550www.mtholyoke.edu/acad/polit/damy/BeginnningReading/types.htm, dead, In the United Kingdom, it is generally called the alternative vote (AV).WEB, Alternative Vote,www.electoral-reform.org.uk/voting-systems/types-of-voting-system/alternative-vote/, 30 May 2019, www.electoral-reform.org.uk, In the United States, IRV is often conflated with ranked-choice voting (RCV);WEB, FairVote.org, Ranked Choice Voting / Instant Runoff,www.fairvote.org/rcv, 30 May 2019, FairVote, however, this conflation is not completely standard,WEB,ballotpedia.org/Ranked-choice_voting_(RCV), Ranked-choice voting (RCV), and social choice theorists tend to prefer more explicit terms.IRV elections are a virtual (instant) variant on exhaustive elimination. In each round, voters choose a favourite candidate; the last-place finisher is eliminated and another round is held. IRV elections automate this process by having voters rank candidates from first to last in order of preference. Voting can then be completed “instantly” by automatically reassigning each voter’s ballot to their alternate (i.e. second) choice. This process continues until every candidate except one has been eliminated, at which point they are declared the winner.IRV is used in national elections in several countries. In Australia, it is used to elect members of the federal House of Representatives,WEB, 23 April 2014, Australian Electoral Commission,www.aec.gov.au/, 30 April 2014, Aec.gov.au, as well as the lower houses in most states, and in some local government elections. It is used to elect the president of India, the president of Ireland,WEB, 1995, Ireland Constitution, Article 12(2.3),www.servat.unibe.ch/icl/ei00000_.html, 15 February 2008, International Constitutional Law, and the National Parliament of Papua New Guinea,WEB, 10 April 2017, Understanding the Limited Preferential Voting system – EMTV Online,emtv.com.pg/understanding-the-limited-preferential-voting-system/, 18 February 2021, as well as the Academy Award for Best Picture.WEB, 12 Mar 2023, How are Oscars winners decided? Here’s how the voting process works, PBS,www.pbs.org/newshour/arts/how-are-oscars-winners-decided-heres-how-the-voting-process-works, 2 March 2024,

Election procedure

Process

(File:IRV_counting_flowchart.svg|thumb|Flowchart of instant-runoff voting)In instant-runoff voting, as with other ranked election methods, each voter orders candidates from first to last. On their ballot, voters mark a ‘1’ beside their first-round vote, a ‘2’ beside their second (alternative) vote, who receives their vote if the first candidate is eliminated; and so on until every candidate has been ranked.WEB, How to make your vote count,www.aec.gov.au/Voting/How_to_Vote/files/how-to-make-your-vote-count.pdf, 22 March 2023, Australian Electoral Commission, The instant-runoff procedure is as follows:

1. Eliminate the candidate with the fewest votes.
2. If only one candidate remains, elect this candidate and stop.
3. Otherwise, re-assign ballots for eliminated candidate to the next choice, and go back to 1.

Ballots assigned to eliminated candidates are added to the totals of one of the remaining candidates based on the next preference ranked on each ballot. The process repeats until one candidate achieves a majority of the vote.

Terminology

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.WEB, 15 February 2001, Second Report: Election of a Speaker,publications.parliament.uk/pa/cm200001/cmselect/cmproced/40/4005.htm, 18 February 2008, House of Commons Select Committee on Procedure, It is also known as the alternative vote, transferable vote, ranked-choice voting (RCV), single-seat ranked-choice voting, or preferential voting.JOURNAL, Cary, David, 1 January 2011, Estimating the Margin of Victory for Instant-runoff Voting,dl.acm.org/citation.cfm?id=2028012.2028015, Proceedings of the 2011 Conference on Electronic Voting Technology/Workshop on Trustworthy Elections, EVT/WOTE’11, 3, Britons and New Zealanders generally call IRV the “alternative vote” (AV).WEB, 8 February 2012, BBC News – Alternative vote,www.bbc.com/news/uk-politics-12910547, 9 October 2019, bbc.com, British Broadcasting Corporation, WEB, 30 September 2017, Opinion: OUSA Needs the Alternative Vote,www.critic.co.nz/news/article/7194/opinion-ousa-needs-the-alternative-vote, 9 October 2019, Critic – Te Arohi, Otago University Students’ Association, Otago, New Zealand, Australians, who use IRV for most single winner elections, call IRV “preferential voting”.NEWS, 11 December 2020, Liberal plan to change federal voting laws may have crossbench support,www.theguardian.com/australia-news/2020/dec/12/liberal-plan-to-change-federal-voting-laws-may-have-crossbench-support, 13 February 2021, The Guardian, While this term is widely used by Australians, it is somewhat of a misnomer: Depending on how “preferential” is defined, the term would either include all voting systems or else would exclude IRV (as it fails positive responsiveness, implying ballot markings cannot be reinterpreted as “preferences” in the traditional sense).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. 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.Appendix D, Instant Runoff Voting, San Francisco Charter § 13.102sfgov.org/ccsfgsa/sites/default/files/Voting%20Systems%20Task%20Force/AppendixD__.pdf.WEB, Arntz, John, 2 February 2005, Ranked-Choice Voting: A Guide for Candidates,www.fairvote.org/media/irv/sanfrancisco/RCVCandidateGuide04.pdf,fairvote.org/media/irv/sanfrancisco/RCVCandidateGuide04.pdf," title="web.archive.org/web/20081202040611fairvote.org/media/irv/sanfrancisco/RCVCandidateGuide04.pdf,">web.archive.org/web/20081202040611fairvote.org/media/irv/sanfrancisco/RCVCandidateGuide04.pdf, 2 December 2008, 25 August 2009, Department of Elections: City and County of San Francisco, 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., As a result of American influence, the term ranked-choice voting is often used in Canada as well.WEB, What is Ranked Choice Voting?,www.london.ca/city-hall/elections/ranked-choice-voting/Pages/What-is-Ranked-Choice-Voting.aspx,www.london.ca/city-hall/elections/ranked-choice-voting/Pages/What-is-Ranked-Choice-Voting.aspx," title="web.archive.org/web/20180226101409www.london.ca/city-hall/elections/ranked-choice-voting/Pages/What-is-Ranked-Choice-Voting.aspx,">web.archive.org/web/20180226101409www.london.ca/city-hall/elections/ranked-choice-voting/Pages/What-is-Ranked-Choice-Voting.aspx, 26 February 2018, City of London, American NGO FairVote has promoted the terminology “ranked-choice voting” to refer to IRV,WEB, 17 August 2019, How RCV Works,www.fairvote.org/rcv#how_rcv_works, 17 August 2018, FairVote, 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.{{Cn|date=May 2024}}IRV is occasionally referred to as Hare’s methodENCYCLOPEDIA, Voting Methods, The Stanford Encyclopedia of Philosophy,plato.stanford.edu/archives/fall2019/entries/voting-methods/, Pacuit, Eric, 24 June 2019, 3 August 2011, Zalta, Edward N., Fall 2019, plato.stanford.edu, (after Thomas Hare) to differentiate it from other ranked-choice voting methods such as majority-choice voting, Borda, and Bucklin.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.WEB, Proportional Representation,www.citizensinformation.ie/en/government_in_ireland/elections_and_referenda/voting/proportional_representation.html, 17 August 2019, Citizens Information Board, State law in South CarolinaWEB, South Carolina General Assembly : 116th Session, 2005–2006,www.scstatehouse.gov/sess116_2005-2006/bills/3720.doc, 1 March 2015, Scstatehouse.gov, and ArkansasWEB, Bill Information,www.arkleg.state.ar.us/assembly/2005/R/Pages/BillInformation.aspx?measureno=HB1770, 28 January 2015, Arkleg.state.ar.us, 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.

Properties, advantages, and disadvantages

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.J. R. Chamberlin and M. D. Cohen, ‘Toward Applicable Social Choice Theory...’, (1978). 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. These issues are illustrated in the following election:(File:IRVCopeland.png|thumb|In IRV for a polarized election between left, right, and centre, the votes for B are not wasted, but the consensus candidate (B) is not elected){| class=“wikitable“|+Simple election example|First choice!A! colspan=“2” |B!C|Second choice!B!A!C!B!Voters|36%|10%|20%|34%

• A wins plurality vote: second place preferences are ignored, so candidate A wins with 36 percent of the vote as against 34 percent for C and 30 percent (10 + 20) for B.
• C wins IRV vote: candidate B gets the fewest first place votes and is therefor eliminated in the first round. Candidate C gets more of B’s second choice preferences than candidate A, winning the second round by 54 percent (20 + 34) to 46 percent (36 + 10). This result is the same as would occur if there was a primary with 3 candidates and a general election with the two remaining candidates (assuming no voters changed their preferences before the general election). Every voter gets a say in the final runoff, so no votes are wasted.
• B wins Condorcet methods, such as bottom-two runoff IRV: in the first round candidates B and C are in last place, so they go head to head. Candidate A’s second place votes go to candidate B, so candidate B wins 66 percent (36 + 10 + 20) to 34 percent over candidate C. In the second runoff round candidate C has been eliminated so candidates A and B go head to head. Candidate C’s second place votes go to candidate B, so candidate B wins 64 percent (10 + 20 + 34) to 36 percent over candidate A.

Invalid, incomplete and exhausted ballots

{{Anchor|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.Because the ballot marking is more complex than X voting, there can be an increase in spoiled ballots. In Australia, voters are required to write a number beside every candidate,WEB, 28 June 2016, Voting in the House of Representatives,aec.gov.au/Voting/How_to_Vote/Voting_HOR.htm, 9 December 2018, Australian Electoral Commission, and the rate of spoiled ballots is sometimes five times more common than plurality voting elections.WEB, 25 October 2010, Busting the Myths of AV,www.no2av.org/why-vote-no/av-myth-busting/,www.no2av.org/why-vote-no/av-myth-busting/," title="web.archive.org/web/20110208014140www.no2av.org/why-vote-no/av-myth-busting/,">web.archive.org/web/20110208014140www.no2av.org/why-vote-no/av-myth-busting/, 8 February 2011, 17 April 2011, No2av.org, {{Unreliable source?|date=January 2021}} Since Australia has compulsory voting, however, it is difficult to tell how many ballots are deliberately spoiled.WEB, 28 February 2011, Informal Voting – Two Ways of Allowing More Votes to Count,blogs.abc.net.au/antonygreen/2011/02/informal-voting-two-ways-of-allowing-more-votes-to-count.html, 15 August 2011, ABC Elections, Where complete rankings are not required, a ballot may become inactive (be declared exhausted) if it is up for transfer and none of the candidates marked as lower ranked choices on that ballot are still in the running. In both cases, even in the instances of high rates of spoiled or exhausted votes, their number is much less than the amount of wasted votes under single-member plurality, where as much as 82 percent of votes cast do not produce representationwww.toronto.ca/wp-content/uploads/2017/08/9059-election-2014-clerksofficialdeclarationofresults.pdf {{bare URL PDF|date=March 2024}}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.WEB, 1 August 2008, Instant Runoff Voting and Its Impact on Racial Minorities,politicalreform.newamerica.net/files/irvracememo.pdf,politicalreform.newamerica.net/files/irvracememo.pdf," title="web.archive.org/web/20110615181347politicalreform.newamerica.net/files/irvracememo.pdf,">web.archive.org/web/20110615181347politicalreform.newamerica.net/files/irvracememo.pdf, 15 June 2011, 15 August 2011, New America Foundation, 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.JOURNAL, 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, 10.1016/j.electstud.2014.11.006, 11159132, As one point of comparison, the number of votes cast in the 190 regularly scheduled primary runoff elections for the US House and US Senate from 1994 to 2016 decreased from the initial primary on average by 39 percent, according to a 2016 study by FairVote.WEB,fairvote.app.box.com/v/federalprimaryrunoffs2016, Federal Runoffs 2016 report.pdf | Powered by Box, fairvote.app.box.com,

Resistance to strategy

Instant-runoff voting has notably high resistance to tactical voting when it elects the Condorcet winner. IRV does not demonstrate resistance to tactical voting when it does not elect the Condorcet winner.{{Cn|date=January 2024}}

Party strategizing

The complexity of strategy under instant-runoff voting means parties and candidates must often explain to voters how they should assign their lower preferences or provide them with a prepared ballot. This is especially common in Australia, where voters must rank all candidates to cast a valid ballot; as a result, over 95 percent of Australians used a pre-filled ballot in 2016.WEB, 25 January 2018, The new Senate voting system and the 2016 election, Figure 3,apo.org.au/sites/default/files/resource-files/2018-01/apo-nid129571.pdf, Parliament of Australia, Department of Parliamentary Services, Preference deals between parties (where one party’s voters agree to place another party’s voters second, in return for their doing the same) can lead to candidates winning seats off the back of far-downballot preferences voters were not even aware they had indicated. In one particularly notorious example, the Minor Party Alliance successfully manipulated this system to win several seats in 2016, despite receiving almost no first-preference votes.

Tactical voting

{{See also|Tactical voting#Instant runoff voting}}The Gibbard–Satterthwaite theorem demonstrates that no (deterministic, non-dictatorial) voting method using only the preference rankings of the voters can be entirely immune from tactical voting. This implies that IRV is susceptible to tactical voting in some circumstances.Research concludes that IRV is one of the voting methods least vulnerable to tactical voting, with theorist Nicolaus Tideman noting that, “alternative voting is quite resistant to strategy”,{{cn|date=May 2024}} and Australian political analyst Antony Green dismissing suggestions of tactical voting.WEB, 11 October 2011, How to Vote Guide,blogs.abc.net.au/antonygreen/2010/07/how-to-vote-guide.html, 29 January 2017, Antony Green’s Election Blog, What is the best way to vote strategically? The best strategic vote is to number the candidates in the order you would like to see them elected. ... in electorate of more than 90,000 voters, and without perfect knowledge, such a strategy is not possible., By not meeting the monotonicity, Condorcet winner, and participation criteria, IRV may incentivize forms of tactical voting (such as compromising) when voters have sufficient information about other voters’ preferences, such as from accurate pre-election polling.{{cn|date=March 2024}} FairVote mentions that monotonicity failure can lead to situations where “having more voters rank [a] candidate first, can cause [the candidate] to switch from being a winner to being a loser”.WEB, Monotonicity and IRV – Why the Monotonicity Criterion is of Little Import,archive.fairvote.org/?page=2261, 17 April 2011, archive.fairvote.org, This occurs when a mutual majority exists which would elect a different candidate than the Condorcet candidate and a minority coalition running off to a single candidate exceeds one-half the size of this majority: the minority candidate cannot be eliminated until the mutual majority runs off to a majority winner. Moving the winner to the top of the minority ballots can shrink the minority sufficiently for their candidate to be eliminated, and their votes then cause the election of a different candidate.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.The 2009 mayoral election in Burlington, Vermont, 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 lost in the final round (a Republican who led in first choices) preferred the Condorcet winner, a Democrat, to the IRV winner, the Progressive Party nominee. If 371 (24.7%) out of the 1,510 backers of the Republican candidate (who also preferred the Democrat over the Progressive candidate for mayor) had insincerely raised the Democrat from their second choice to their first (not changing their rankings relative to their least favourite candidate, the Progressive), the Democrat would then have advanced to the final round (instead of their favourite), defeated any opponent, and proceeded to win the IRV election.{{cn|date=March 2024}} This is an example of potential voter regret in that these voters who sincerely ranked their favourite candidate as first, find out after the fact that they caused the election of their least favourite candidate, which can lead to the voting tactic of compromising.

Spoiler effect

The spoiler effect is when a difference is made to the anticipated outcome of an election due to the presence on the ballot paper of a candidate who will lose. Most often this is when two or more politically similar candidates divide the vote for the more popular end of the political spectrum. That is, each receives fewer votes than a single opponent on the unpopular end of the spectrum who is disliked by the majority of voters but who wins from the advantage that, on that unpopular side, they are unopposed. Strategic nomination relies on triggering this situation, and requires understanding of both the electoral process and the demographics of the district.Proponents of IRV claim that IRV eliminates the spoiler effect,WEB, Instant Run-Off Voting,archive.fairvote.org/factshts/irv.htm, 29 January 2017, archive.fairvote.org, IRV removes the “spoiler effect” whereby minor party or independent candidates knock off major party candidates, increasing the choices available to the voters., WEB, Cal IRV FAQ,www.cfer.org/learn/irvfaq.php, 29 January 2017, Californians for Electoral Reform, IRV completely eliminates the ‘spoiler’ effect – that is, votes split between a weak and a strong candidate won’t cause the strong candidate to lose if s/he is the second choice of the weak candidate’s voters., NEWS, OP-ED {{!, No More Spoilers? Instant Runoff Voting Makes Third Parties Viable, Improves Democracy |url=http://www.ctnewsjunkie.com/archives/entry/op-ed_no_more_spoilers_instant_runoff_voting_makes_third_parties_viable/ |first1=Kiernan |last1=Majerus-Collins |date=12 June 2015 |access-date=20 April 2017 |work=CT News Junkie |quote=Instant-runoff voting ends the spoiler effect forever}}{{Citation |last=CGP Grey |title=The Alternative Vote Explained |date=6 April 2011 |url=https://www.youtube.com/watch?v=3Y3jE3B8HsE&t=3m4s |website=YouTube |access-date=20 April 2017 |quote=Alternative Vote: Stops the Spoiler Effect |url-status=live |archive-url=https://web.archive.org/web/20170810135828www.youtube.com/watch?v=3Y3jE3B8HsE&t=3m4s |archive-date= 10 August 2017 }} 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,BOOK, Borgers, Christoph,books.google.com/books?id=u_XMHD4shnQC, Mathematics of Social Choice: Voting, Compensation, and Division, SIAM, 2010, 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, BOOK, Poundstone, William,books.google.com/books?id=_24bJHyBV6sC, Gaming the Vote: Why Elections Aren’t Fair (and What We Can Do About It), Farrar, Straus and Giroux, 2009, 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, NEWS, 20 May 2015, The Spoiler Effect,electology.org/spoiler-effect, 29 January 2017, The Center for Election Science, {{Citation |last=The Center for Election Science |title=Favorite Betrayal in Plurality and Instant Runoff Voting |date=2 December 2013 |url=https://www.youtube.com/watch?v=JtKAScORevQ |access-date=29 January 2017}}JOURNAL, Bristow-Johnson, R., 2023, The failure of Instant Runoff to accomplish the purpose for which it was adopted: a case study from Burlington Vermont,doi.org/10.1007/s10602-023-09393-1, PDF, Const Polit Econ, 34, 3, 378–389, 10.1007/s10602-023-09393-1, 255657135, 9 January 2024, 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 (favourite betrayal).JOURNAL, 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,www.ssrn.com/abstract=883058, SSRN Working Paper Series, 340, 10.2139/ssrn.883058, 1556-5068, 155750146, 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, WEB, Comments, 9 December 2016, The False Promise of Instant Runoff Voting,www.cato-unbound.org/2016/12/09/jason-sorens/false-promise-instant-runoff-voting, 29 January 2017, Cato Unbound, They’ll have a strategic incentive to falsify their preferences., 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.WEB, 2009 Burlington Mayor IRV Failure,bolson.org/~bolson/2009/20090303_burlington_vt_mayor.html, 29 January 2017, bolson.org, 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.ARXIV, 2209.04764v1, econ.GN, Adam, Graham-Squire, David, McCune, A Mathematical Analysis of the 2022 Alaska Special Election for US House, 2022,www.washingtonpost.com/opinions/2022/11/01/alaska-final-four-primary-begich-palin-peltola/ {{bare URL inline|date=March 2024}}In practice, IRV does not seem to discourage candidacies. In Australia’s House of Representatives 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.WEB, House of Representatives Results,results.aec.gov.au/13745/website/HouseResultsMenu-13745.htm, 1 March 2015, Results.aec.gov.au, A study of ballot image data found that all of the 138 RCV elections held in four Bay Area cities in California elected the Condorcet winner, including many with large fields of candidates and 46 where multiple rounds of counting were required to determine a winner.WEB, 6 January 2017, Every RCV Election in the Bay Area So Far Has Produced Condorcet Winners,www.fairvote.org/every_rcv_election_in_the_bay_area_so_far_has_produced_condorcet_winners, 13 February 2017, fairvote.org,

Proportionality

IRV is a single-winner application of the proportional voting system known as STV, with a Droop quota (50%+1). Like all winner-take-all voting methods, 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. A simulation of IRV in the 2010 UK general election by the Electoral Reform Society concluded that the election would have altered the balance of seats among the three main parties, but the number of seats won by minor parties would have remained unchanged.NEWS, Travis, Alan, 10 May 2010, Electoral reform: Alternative vote system would have had minimal impact on outcome of general election,www.theguardian.com/politics/2010/may/10/alternative-vote-minimal-impact-general-election, 1 April 2011, The Guardian, London,

Australia

Australia, a nation with a long record of using IRV for the election of legislative bodies, has had representation in its parliament broadly similar to that expected by plurality methods.Medium-sized parties, such as the National Party of Australia, can co-exist with coalition partners such as the Liberal Party of Australia, and can compete against it without fear of losing seats to other parties due to vote splitting, although generally in practice these two parties only compete against each other when a sitting member of the coalition leaves Parliament.History of Preferential Voting in Australia, Australian Broadcasting Corporation, 2004 Election Guide. ”Such a long lasting Coalition would not have been possible under first part the post voting” IRV is more likely to result in legislatures where no single party has an absolute majority of seats (a hung parliament),{{citation needed|date=May 2011}} but does not generally produce as fragmented a legislature as a fully proportional method, such as is used for the House of Representatives of the Netherlands, where coalitions of numerous small parties are needed for a majority.

Criticism

Voter confusion and legitimacy of elections

Some critics of IRV have noted that because of its greater complexity, IRV can create distrust among voters who misunderstand it. Often such criticism is related to allegations that IRV is a kind of plural voting. In Ann Arbor, 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.WEB, Walter, Benjamin, History of Preferential Voting in Ann Arbor,www.migreens.org/hvgreens/aa-irv01.htm,migreens.org/hvgreens/aa-irv01.htm," title="web.archive.org/web/20120208053837migreens.org/hvgreens/aa-irv01.htm,">web.archive.org/web/20120208053837migreens.org/hvgreens/aa-irv01.htm, 8 February 2012, The argument that IRV represents plural voting is sometimes used in arguments over the “fairness” of the method, and has led to frequent legal challenges in the United States.WEB, Ann Arbor Law Suit,archive.fairvote.org/?page=397, 10 May 2011, FairVote, The same argument was advanced in opposition to IRV in Maine. Governor Paul LePage claimed, ahead of the 2018 primary elections, that IRV would result in “one person, five votes”, as opposed to “one person, one vote”.WEB, Leary, Mal, 12 June 2018, Opposed To Ranked-Choice Voting, LePage Says He Might Not Certify Primary Election Results,www.mainepublic.org/post/opposed-ranked-choice-voting-lepage-says-he-might-not-certify-primary-election-results, 14 January 2019, Maine Public, In litigation following the results of the 2018 election for Maine’s 2nd congressional district, Representative Bruce Poliquin claimed that IRV allowed his opponents to “cast ballots for three different candidates in the same election”.PACER, Baber, Dunlap, Complaint, 1, 13 November 2018, 8169811, ME, 1, 18, cv, 00465, 13 January 2019, Federal judge Lance Walker rejected this claim, and the 1st circuit court denied Poliquin’s emergency appeal, leading to Poliquin dropping his claim.NEWS, 22 December 2018, 1st Circuit ends Poliquin’s efforts to keep House seat,bangordailynews.com/2018/12/21/politics/1st-circuit-ends-poliquins-efforts-to-keep-house-seat/, 17 August 2019, Bangor Daily News,

Similarity to plurality

Because it is effectively a “repeated plurality” vote, results with instant-runoff voting are typically very similar to those under plurality, and instant-runoff behaves similarly to plurality. This has led many commentators and voting reform advocates to question whether IRV is worth the substantial additional costs and complexity needed to ultimately elect the same winner. For example, instant-runoff voting fails the Condorcet criterion, meaning it fails to elect consensus winners.Most instant-runoff voting elections are won by the candidate who leads in first-choice rankings, choosing the same winner as plurality voting. In Australia, the 1972 federal election had the highest proportion of winners who would not have won under first past the post—with only 14 out of 125 seats not won by the plurality candidate.WEB, Green, Antony, 11 May 2010, Preferential Voting in Australia,www.abc.net.au/news/2010-05-12/preferential-voting-in-australia/9389472, 1 November 2020, www.abc.net.au,

Participation

The effect of IRV on voter turnout is difficult to assess. In a lengthy 2021 report, researchers at New America, a think tank based in Washington, D. C., said:WEB, What We Know About Ranked-Choice Voting,newamerica.org/political-reform/reports/what-we-know-about-ranked-choice-voting/, New America, With our sample of cases largely limited to municipal and often nonpartisan elections (in relatively engaged localities), the best we can say for RCV [ranked-choice voting], independent of timing considerations, is that it may increase local turnout from a pathetic baseline to a slightly less pathetic level by attracting more, and more diverse, candidates. However, if RCV is able to combine the primary and the general election into a single election, held in November alongside other national elections, it is likely to have a more powerful effect in boosting turnout.The report concluded:NEWS, Drutman, Lee, Strano, Maresa, 10 November 2021, What We Know About Ranked-Choice Voting,www.newamerica.org/political-reform/reports/what-we-know-about-ranked-choice-voting/conclusion/, 28 February 2023, New America, And to the extent that RCV combines the primary and the general election into one, it increases turnout. However, many of the other hoped-for benefits, such as more diverse candidates (by gender, race, and ideology), higher turnout, and more viable parties, are harder to detect. Nor is there any evidence that RCV changes policy outcomes[...] In most elections, the candidate who would have won under plurality voting is also the candidate who won under ranked-choice voting.

History and use

History

This method was considered by the Marquis de Condorcet as early as 1788, though only to condemn it for its ability to eliminate a candidate preferred by a majority of voters.JOURNAL, Nanson, E. J., 1882, Methods of election: Ware’s Method,archive.org/details/transactionsproc1719roya/page/206, Transactions and Proceedings of the Royal Society of Victoria, 17, 206, The method was, however, mentioned by Condorcet, but only to be condemned., BOOK, Condorcet, Jean-Antoine-Nicolas de Caritat,books.google.com/books?id=d0cwAAAAYAAJ&q=Oeuvres%20de%20Condorcet,%20Volume%2013&pg=PA243, On the Constitution and the Functions of Provincial Assemblies, 1788, Complete Works of Condorcet, 13, 1804, 243, fr, En effet, lorsqu’il y a plus de trois concurrents, le véritable vÅ“u de la pluralité peut être pour un candidat qui n’ait eu aucune des voix dans le premier scrutin., IRV can be seen as a special case of the single transferable vote method, which began use in the 1850s. It is historically known as Ware’s method, due to the implementation of STV in 1871 at Harvard College by American architect William Robert Ware, who suggested it could also be used for single-winner elections.BOOK, Ware, William R.,books.google.com/books?id=W7QRAAAAYAAJ&pg=PA192, Application of Mr. Hare’s system of voting to the nomination of overseers of Harvard College., 1871, 81791186, It is equally efficient whether one candidate is to be chosen, or a dozen., WEB, Reilly, Benjamin, The Global Spread of Preferential Voting: Australian Institutional Imperialism,archive.fairvote.org/articles/reilly.pdf, 17 April 2011, FairVote.org, Ware noted that the vote counting took only two or three hours, less time than required to count votes in the previous university election when limited voting was used and each voter cast five votes.BOOK, Ware, William R.,books.google.com/books?id=W7QRAAAAYAAJ&pg=PA192, Application of Mr. Hare’s system of voting to the nomination of overseers of Harvard College., 1871, 81791186, Unlike the single transferable vote in multi-seat elections, however, the only votes transferred are cast by backers of candidates who have been eliminated. There are no transfers of surplus votes as under STV.The first known use of an IRV-like method in a governmental election was in the 1893 general election in the Colony of Queensland (in present-day Australia).WEB, McLean, Iain, October 2002, Australian electoral reform and two concepts of representation,www.nuffield.ox.ac.uk/Politics/papers/2002/w23/mclean.pdf, 22 February 2008, 11, The variant used for this election was a “contingent vote”, where all candidates but two are eliminated in the first round, with one of the last two elected by majority after votes of the others are transferred. Queensland used contingent voting until 1942, one of the longest uses of the system anywhere.Bowler and Grofman, Elections in Australia, Ireland and Malta, p. 40IRV in its true form (what was called Alternative Voting at the time) was first used in Western Australia, in the 1908 state election. To form up a majority behind one candidate, candidates are dropped one by one. The lower houses of all Australian states (except Tasmania and ACT) and the Australian House of Representatives are elected through IRV. The last state to adopt AV was Queensland in 1962, It had switched from contingent voting to single-member plurality in 1942.Farrell and McAllister, The Australian Electoral System, p. 50 (Multi-winner STV of the Hare-Clark version was introduced for the Tasmanian House of Assembly at the 1909 state election. ACT used modified d’Hondt (a party-list PR system) to 1995 when it adopted STV.)Farrell and McAllister, The Australian Electoral System, p. 72, 87IRV was introduced for federal (nationwide) elections in Australia after the Swan by-election in October 1918, in response to the rise of the conservative Country Party, representing small farmers. The Country Party split the non-Labor vote in conservative country areas, allowing Labor candidates to win without a majority of the vote. The conservative government of Billy Hughes introduced IRV (in Australia called “preferential voting“) as a means of allowing competition between the Coalition parties without putting seats at risk. It was first used at the Corangamite by-election on 14 December 1918, and at a national level at the 1919 election.WEB, Australian Electoral History: Voting Methods,australianpolitics.com/elections/features/voting-methods-history.shtml,australianpolitics.com/elections/features/voting-methods-history.shtml," title="web.archive.org/web/20110319034900australianpolitics.com/elections/features/voting-methods-history.shtml,">web.archive.org/web/20110319034900australianpolitics.com/elections/features/voting-methods-history.shtml, 19 March 2011, 17 April 2011, Australianpolitics.com, IRV continued to benefit the Coalition until the 1990 election, when for the first time Labor obtained a net benefit from IRV.NEWS, 22 September 2015, The Origin of Senate Group Ticket Voting, and it didn’t come from the Major Parties,www.abc.net.au/news/2015-09-23/the-origin-of-senate-group-ticket-voting-and-it-didnt-come-from-/9388658, ABC News, In 1990, for example, the small Baltic state of Estonia held its first post-Soviet elections under a combination of IRV and STV — a system which had been popularized by Rein Taagepera, an expatriate Estonian political scientist from the University of Californiaarchive.fairvote.org/articles/reilly.pdf {{bare URL PDF|date=March 2024}}In 2000, Bosnia used IRV for its election.

Global use

National level elections {| class“wikitable sortable plainrowheaders”

! scope=“col” | Country! scope=“col” | Body or office! scope=“col” | Type of body or office! scope=“col” | Electoral system! scope=“col” | Total seats! scope=“col” | Notes! scope=“row” | Australia

Australian House of Representatives>House of Representatives|Lower chamber of legislature|IRV|151|

! rowspan=“2” scope=“row” | Ireland

President of Ireland>President|Head of State|IRV||

|Dáil Éireann|Lower chamber of legislature|Single transferable vote (STV), by-elections using IRV|158The 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.|! scope=“row” | Papua New Guinea

National Parliament of Papua New Guinea>National Parliament|Unicameral legislature|IRV|109|

! rowspan=“3” scope=“row” | United States

President of the United States>President (via Electoral College)|Head of State and Government|Alaska and Maine use IRV to select the state winner. In Maine, 2 electors are allocated to the winner and the others (currently 2) are allocated by congressional district, while in Alaska, the winner gets all electors of the state in the Electoral College system (as Alaska has only one at-large district, the effect is the same).|7 EVselectoral votes (out of 538)|

United States House of Representatives>House of Representatives|Lower chamber of legislature

IRV in MaineNonpartisan primary system with IRV in the second round (among top four candidates) in Alaska.WEB, 10 November 2016, Maine became the first state in the country Tuesday to pass ranked-choice voting,www.boston.com/news/politics/2016/11/10/maine-became-the-first-state-in-the-country-to-pass-ranked-choice-voting, 10 November 2016, WEB, 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/20180404201657mainerankedchoice.vote/ |url-status=dead }}NEWS, Russell, Eric, 12 June 2018, Mainers vote to keep ranked-choice voting, with supporters holding commanding lead,www.pressherald.com/2018/06/12/ranked-choice-voting-takes-lead-in-early-balloting/, 13 June 2018, Portland Press Herald, WEB, Alaska Ballot Measure 2, Top-Four Ranked-Choice Voting and Campaign Finance Laws Initiative (2020),ballotpedia.org/Alaska_Ballot_Measure_2,_Top-Four_Ranked-Choice_Voting_and_Campaign_Finance_Laws_Initiative_(2020), 17 November 2020, Ballotpedia, |3 (out of 435)|

United States Senate>Senate|Upper chamber of legislature|4 (out of 100)|

Robert’s Rules of Order“>

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 ProcedurePARL, TSC, 148, 4th, and Riddick’s Rules of Procedure,PARL, RID, 145, 1985, 1985, take a similar stance.

Similar methods

Runoff voting

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.WEB, Glossary: Exhaustive ballot,www.securevote.com.au/gloss_of_terms.html#e, 6 May 2010, Securevote.com.au, 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

(File:IRV-toptwo_flowchart.png|thumb|Top-two IRV)The contingent vote, also known as “top-two IRV” or the “supplementary vote”, 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 the elections for Mayor of London in the United Kingdom, voters rank a specified maximum number of candidates. In London, the supplementary vote allows 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.WEB, Initiatives – Pew Center on the States,www.electionline.org/Portals/1/Publications/SC.EAP.2006primary.pdf,www.electionline.org/Portals/1/Publications/SC.EAP.2006primary.pdf," title="web.archive.org/web/20080516235221www.electionline.org/Portals/1/Publications/SC.EAP.2006primary.pdf,">web.archive.org/web/20080516235221www.electionline.org/Portals/1/Publications/SC.EAP.2006primary.pdf, 16 May 2008, 6 May 2010, Electionline.org, Louisiana uses it only for members of the United States Service or who reside overseas.{{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}}
• 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.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.

Variations

File:2016-ballot-paper-Higgins.png|thumb|Example of a full preferential ballot paper from the Australian House of RepresentativesAustralian House of RepresentativesA 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.WEB, 28 January 2020, Voting system,www.ecq.qld.gov.au/how-to-vote/voting-systems, 17 November 2020, www.ecq.qld.gov.au, Electoral Commission of Queensland, WEB, Stevens, Bronwyn, 27 January 2015, Are Queenslanders in danger of ‘wasting’ their votes?,www.theconversation.com/amp/are-queenslanders-in-danger-of-wasting-their-votes-35919, 28 November 2020, The Conversation, In a full-preferential voting method, voters are required to mark a preference for every candidate standing.WEB, Electoral Systems,www.eca.gov.au/systems/single/by_category/preferential.htm,www.eca.gov.au/systems/single/by_category/preferential.htm," title="web.archive.org/web/20080309220219www.eca.gov.au/systems/single/by_category/preferential.htm,">web.archive.org/web/20080309220219www.eca.gov.au/systems/single/by_category/preferential.htm, 9 March 2008, 15 February 2008, Electoral Council of Australia, 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.WEB, Ranked-Choice Voting,www.acgov.org/rov/rcv/faq.htm, 15 December 2016, Registrar of Voters, Alameda County, 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., A version of instant-runoff voting applying to the ranking of parties was first proposed for elections in Germany in 2013REPORT, 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), Breyer, Patrick, November 2013, Piratenfraktion im Schleswig-Holsteinischen Landtag, de, (Drs. 18/385), Alternative II: Einführung einer Ersatzstimme,www.landtag.ltsh.de/infothek/wahl18/umdrucke/1900/umdruck-18-1916.pdf, as spare vote.WEB, Dual Level Voting - Granting equal votes in a proportional election with a threshold,www.dualvoting.com/, www.dualvoting.com,

Voting method criteria

Scholars rate voting methods using mathematically derived voting method criteria, which describe desirable features of a method. No ranked-preference method can meet all of the criteria, because some of them are mutually exclusive, as shown by statements such as Arrow’s impossibility theorem and the Gibbard–Satterthwaite theorem.Many of the mathematical criteria by which voting methods are compared were formulated for voters with ordinal preferences. If voters vote according to the same ordinal preferences in both rounds, criteria can be applied to two-round systems of runoffs, and in that case, each of the criteria failed by IRV is also failed by the two-round system as they relate to automatic elimination of trailing candidates. Partial results exist for other models of voter behavior in the two-round method: see the two-round system article’s criterion compliance section for more information.

Satisfied criteria

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. However, IRV can still elect the “second-worst” candidate when the two worst candidates are the only ones remaining in the final round.JOURNAL, Nanson, E. J., 1882, Methods of election,archive.org/details/transactionsproc1719roya/page/207, Transactions and Proceedings of the Royal Society of Victoria, 19, 207–208, although Ware’s method cannot return the worst, it may return the next worst., 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”. IRV meets this criterion.WEB, Green-Armytage, James, 2004, A Survey of Basic Voting Methods,www.econ.ucsb.edu/~armytage/voting/survey.htm,www.econ.ucsb.edu/~armytage/voting/survey.htm," title="web.archive.org/web/20130603015026www.econ.ucsb.edu/~armytage/voting/survey.htm,">web.archive.org/web/20130603015026www.econ.ucsb.edu/~armytage/voting/survey.htm, 3 June 2013, 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”.The majority criterion states that “if one candidate is preferred by an absolute majority of voters, then that candidate must win”. 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. The resolvability criterion states that “the probability of an exact tie must diminish as more votes are cast”.

Pathologies of IRV

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.WEB, FairVote, Understanding the RCV Election Results in District 10,www.fairvote.org/understanding-the-rcv-election-results-d10,www.fairvote.org/understanding-the-rcv-election-results-d10," title="web.archive.org/web/20110726045123www.fairvote.org/understanding-the-rcv-election-results-d10,">web.archive.org/web/20110726045123www.fairvote.org/understanding-the-rcv-election-results-d10, 26 July 2011, 17 April 2011, FairVote.org, Systems which fail Condorcet but pass mutual majority can exclude voters outside the mutual majority from the vote, essentially becoming an election between the mutual majority.{{citation needed|date=November 2020}} IRV demonstrates this exclusion of up to 50 percent of voters, notably in the 2009 Burlington mayoral election where the later rounds became a runoff between the mutual majority of voters favouring Andy Montroll and Bob Kiss. This can recurse: if a mutual majority exists within the mutual majority, then the majority becomes a collegiate over the minority, and the inner mutual majority solely decides the votes of this collegiate.

Spoiler effects

Instant-runoff voting is vulnerable to spoiler effects, as it violates independence of irrelevant alternatives (see below). 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 ranked pairs or score voting.{{cn|date=March 2024}}

Monotonicity criterion

{{Further|Monotonicity criterion#Instant-runoff voting and the two-round system are not monotonic}}The monotonicity criterion says that ranking a candidate higher on your ballot should not cause them to lose. The exact probability of a monotonicity failure depends on the circumstances, but with 3 major candidates, the probabilities range from 14.5 percent under the impartial culture model{{cn|date=March 2024}} to 8.5 percent in the case of a strict left–right spectrum,JOURNAL, Lepelley, Dominique, Chantreuil, Frederic, Berg, Sven, 1996, The likelihood of monotonicity paradoxes in run-off elections, Mathematical Social Sciences, 31, 3, 133–146, 10.1016/0165-4896(95)00804-7, quickly approaching 100 percent for more than a handful of candidates.

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: about 50 percent of elections where IRV elects a different candidate from plurality involve participation failures.JOURNAL, Ray, Depankar, 1986, On the practical possibility of a ‘no show paradox’ under the single transferable vote, Mathematical Social Sciences, 11, 2, 183–189, 10.1016/0165-4896(86)90024-7,

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.{{cn|date=March 2024}}

Examples

Tennessee capital election

{{Tenn_voting example}}It takes three rounds to determine a winner in this election:{| class=“wikitable“!!1st!2nd! colspan=“2” |3rd|Knoxville|17%|32%|58%|{{Tick}}|Memphis|42%|42%|42%|{{Xmark}}|Nashville|26%|26%{{Xmark}}

Eliminated

|Chattanooga|15%{{Xmark}}

Eliminated

Round 1 – In the first round, Chattanooga is eliminated.Round 2 – Chattanooga’s votes go to Knoxville (the closest city to Chattanooga). Nashville is in last place and is therefore eliminated.Note that Nashville was both the Condorcet winner and the “most central” city (supported by the median voter). This elimination is an example of a centre squeeze, where a popular consensus candidate is eliminated thanks to a spoiler effect.Round 3 – In the final round, Nashville’s votes are redistributed to Knoxville, giving Knoxville a majority.For comparison, note that a plurality vote would elect Memphis, even though most citizens consider it the worst choice, because 42 percent is larger than any other single city. As Nashville is a Condorcet winner, (Condorcet method#Example: Voting on the location of Tennessee’s capital|Condorcet methods) would elect Nashville.This election is an example of a participation failure because Memphis eliminated Nashville in round 3. If Memphis lost half its population, Nashville (the Memphis voters’ second choice) would have won the election instead of Knoxville (the Memphis voters’ last choice).

1990 Irish presidential election

{{See also|Irish presidential election, 1990}}The 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.{| class=“wikitable”www.electionsireland.org/result.cfm?election=1990P&cons=194, 23 November 2009, ElectionsIreland.org, !Candidate! colspan=“2” |Round 1! colspan=“2” |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%{{Xmark}}

Eliminated

!Exhausted ballots|9,444|0.6%|34,992|2.2%!Total|1,584,095|100%|1,584,095|100%{{clear}}

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 case, it was the candidate who initially placed third (Green candidate Sam Hibbins). Hibbins would ultimately go on to defeat center-left Australian Labor candidate Neil Pharaoh with the help of 31 voters who placed him in 6th place (third-to-last), despite losing the first five rounds of voting.WEB, State Election 2014: Prahran District (Distribution of preference votes),www.vec.vic.gov.au/Results/State2014/distributionPrahranDistrict.html, Victorian Electoral Commission, 25 July 2018, 25 July 2018,web.archive.org/web/20180725092627/https://www.vec.vic.gov.au/Results/State2014/distributionPrahranDistrict.html, dead, In the 7th round, Hibbins narrowly defeated Coalition candidate Clem Newton-Brown by a margin of 277 votes.In this race, Newton-Brown spoiled the election for Labor candidate and Condorcet winner Neil Pharaoh, who likely would have defeated Sam Hibbins by a 3:1 ratio if Newton-Brown had not run.{| class=“wikitable sortable“!Candidate! colspan=“2” |1st!2nd!3rd!4th!5th!6th! colspan=“2” |7th

Clem Newton-Brown (Liberal Party of Australia>LIB)|44.8%|16,582|16,592|16,644|16,726|16,843|17,076|18,363|49.6%

Sam Hibbins (Australian Greens>GRN)|24.8%|9,160|9,171|9,218|9,310|9,403|9,979|18,640|50.4%

Australian Labor Party>ALP)|25.9%|9,586|9,593|9,639|9,690|9,758|9,948{{Xmark}}	Eliminated

Animal Justice Party>AJP)|2.3%|837|860|891|928|999{{Xmark}}	Eliminated

Independent (politician)>IND)|0.7%|247|263|316|349{{Xmark}}	Eliminated

Family First Party>FFP)|0.8%|282|283|295{{Xmark}}	Eliminated

Independent (politician)>IND)|0.6%|227|241{{Xmark}}	Eliminated

Independent (politician)>IND)|0.2%|82{{Xmark}}	Eliminated

!Total|100%|37,003

2009 Burlington mayoral election

{{See also|2009 Burlington mayoral election}}{| class=wikitable style="text-align:right; float:right; margin-left:1em“|+ 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}}

Bob Kiss	Progressive| 2585| +2585| 2981| +396| 4313| +1332

{{Party shading/Republican}}

Kurt Wright	Republican| 2951| +2951| 3294| +343| 4061| +767

{{Party shading/Democratic}}

Andy Montroll	Democrat| 2063| +2063| 2554| +491| 0| −2554

{{Party shading/Independent}}

Dan Smith	Independent| 1306| +1306| 0| −1306

! style="text-align:left;” | Others|| 71| +71| 0| −71 ! style="text-align:left;” | Exhausted|| 4| +4| 151| +147 | 606| +455Under Burlington’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.WEB, Bouricious, Terry, 13 March 2009, Point/Counterpoint: Terry Bouricius Attempts To Rip Professor Gierzynski A New One Over Instant Runoff Voting Controversy (Now With All New Gierzynski Update!),vermontdailybriefing.com/?p=1215,vermontdailybriefing.com/?p=1215," title="web.archive.org/web/20151019002702vermontdailybriefing.com/?p=1215,">web.archive.org/web/20151019002702vermontdailybriefing.com/?p=1215, 19 October 2015, 27 September 2017, Vermont Daily Briefing, the 2009 election suffered from not only the ‘thwarted majorities’ or Condorcet’s paradox, but also the ‘no-show paradox’ that shows that Wright voters who preferred Montroll over Kiss (that is, ranked Montroll 2nd) would have been better staying home and not voting at all., WEB, Olson, Brian, 2009, 2009 Burlington Mayor IRV Failure,bolson.org/~bolson/2009/20090303_burlington_vt_mayor.html, 1 October 2017, bolson.org, This is an IRV failure. The IRV result is clearly not what people actually wanted. More people liked Montroll over Kiss than the other way around, but IRV elected the loser., WEB, Sheldon-hess, Dale, 16 March 2009, IRV Fails in Its Own Backyard,leastevil.blogspot.com/2009/03/irv-fails-in-its-own-backyard.html, 27 September 2017, The Least of All Evils, Montroll would have beaten any other candidate in a one-on-one election., FairVote touted the 2009 election as one of its major success stories,NEWS, Etnier, Carl, 6 March 2009, Instant runoff was success,www.rutlandherald.com/articles/instant-runoff-was-success/, 17 March 2018, Rutland Herald, claiming it helped the city save on costs of a traditional runoffNEWS, Totten, Shay, Burlington Residents Seek Repeal of Instant Runoff Voting,www.sevendaysvt.com/vermont/burlington-residents-seek-repeal-of-instant-runoff-voting/Content?oid=2177125, 17 March 2018, Seven Days, en, 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., and prevented a spoiler effect,WEB, Bouricius, Terry, 17 March 2009, Response to Faulty Analysis of Burlington IRV Election,www.fairvote.org/response-to-faulty-analysis-of-burlington-irv-election, 1 October 2017, FairVote.org, 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, although later analysis showed this not to be the case: without Wright in the election, Montroll would have defeated Kiss in a one-on-one race.JOURNAL, Lewyn, Michael, 2012, Two Cheers for Instant Runoff Voting, Phoenix L. Rev., en, 6, 117, 2276015, election where Democratic candidate for mayor was Condorcet winner but finished third behind Republican and ‘Progressive{{’-, }}FairVote also claimed the election was a success because most voters were able to complete at least one preference on their ranked-choice ballot. However, 16% of voters cast incomplete ballots, and 6% of ballots were thrown out before the final round, leading some observers to question that interpretation.{{cn|date=March 2024}}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).JOURNAL, Felsenthal, Dan S., Tideman, Nicolaus, 2014, Interacting double monotonicity failure with direction of impact under five voting methods, Mathematical Social Sciences, 67, 57–66, 10.1016/j.mathsocsci.2013.08.001, 0165-4896, A display of non-monotonicity under the Alternative Vote method was reported recently, for the March 2009 mayoral election in Burlington, Vermont., JOURNAL, 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, en, 161, 1–2, 1–9, 10.1007/s11127-013-0118-2, 0048-5829, 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, Several electoral reform advocates branded the election a failure after Kiss was elected, despite 54 percent of voters voting for Montroll over Kiss,JOURNAL, 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, 10.1007/s10602-023-09393-1, violating the principle of majority rule.BOOK, Ellenberg, Jordan,archive.org/details/hownottobewrongp0000elle, How Not to Be Wrong: The Power of Mathematical Thinking, 29 May 2014, Penguin, 9780698163843, 385, en, 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., registration, JOURNAL, Stensholt, Eivind, 7 October 2015, What Happened in Burlington?, NHH Dept. Of Business and Management Science, en, Discussion Paper No. 2015/26, 10.2139/ssrn.2670462, 2670462, K was elected even though M was a clear Condorcet winner and W was a clear Plurality winner., free, 11250/2356264, NEWS, Dopp, Kathy, 10 June 2009, IRV much worse than old runoffs,www.aspentimes.com/news/irv-much-worse-than-old-runoffs/, 17 March 2018, The Aspen Times, en, Locals argued the system was convoluted, turned the election into a “gambling game” by disqualifying Montroll for having won too many votes, and “eliminated the most popular moderate candidate and elected an extremist”.{{Election box ranked choice begin|title=Burlington mayoral election, 2009 (summary analysis)}}{{Election box ranked choice candidate with party link|party=Vermont Progressive Party|candidate=Bob Kiss|maxround=3|maxvotes=4313|maxvotespercent=48.0|r1votes=2585|fullwidthvotes=4500}}{{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}}

Comparison to other voting systems

{{Comparison of Schulze to preferential voting systems}}

See also

• Alternative vote plus (AV+), or alternative vote top-up, proposed by the Jenkins Commission in the UK
• Comparison of electoral systems

References

{{Reflist}}

External links

• Preferential Voting at Australian Electoral Commission
• 2010 articles from the www.re-constitution.org.uk/news/articles/37/" title="web.archive.org/web/20100821235240www.re-constitution.org.uk/news/articles/37/">Constitution Society and www.electoral-reform.org.uk/article.php?id=55" title="web.archive.org/web/20100831234824www.electoral-reform.org.uk/article.php?id=55">Electoral Reform Society summarizing the proposed change in the United Kingdom to IRV/Alternative Vote

Practice

• Advantages and disadvantages of AV from the ACE Project Electoral Design Reference Materials
• A Handbook of Electoral System Design {{Webarchive|url=https://web.archive.org/web/20091224082449www.idea.int/ |date=24 December 2009 }} from International IDEA
• Australian Electoral Commission Web Site
  • Australian Senate: {{example needed|please link to a specific page|date=November 2020}}
  • Australian House of Representatives: {{example needed|please link to a specific page|date=November 2020}}
• www.australianpolitics.com/elections/features/preferential.shtml" title="web.archive.org/web/20090722070716www.australianpolitics.com/elections/features/preferential.shtml">Preferential Voting in Australia from Australian Politics.com
• sfgov.org/elections/ranked-choice-voting" title="web.archive.org/web/20170715160018sfgov.org/elections/ranked-choice-voting">San Francisco Department of Elections, California
• Alameda County Registrar of Voters, California
• City of Minneapolis, Minnesota
• Ranked Choice Voting Resource Center

Demonstrations and simulations

• The Star Tribune: How ranked-choice voting works – an interactive graphic
• RankedVote — Online ranked-choice voting platform for voter education with detailed results animations and explanations.
• RCV123.org - Free, non-profit site with on-line and paper ballot ranked-choice voting systems for any group vote.
• AmericanQuorum.com A ranked-choice ballot tool from the Indaba Application Network, including the animated display of an instant runoff.
• BBC: Would the alternative vote have changed history?, illustration of how the results of the last six general elections might have looked had the ‘alternative vote’ system been in place.
• Voting System Visualizations – 2-dimensional plots of results of various methods, with assumptions of sincere voting behavior.
• Simulation Of Various Voting Models for Close Elections Opposition article by Brian Olson.

Advocacy groups and positions

• Yes to Fairer Votes {{Webarchive|url=https://web.archive.org/web/20110419040809www.yestofairervotes.org/ |date=19 April 2011 }} campaign site for the Yes side of the 2011 United Kingdom Alternative Vote referendum
• Washington Post
• WEB,www.fairvote.org/instant-runoff-voting, Ranked Choice Voting,www.fairvote.org/instant-runoff-voting," title="web.archive.org/web/20131231115533www.fairvote.org/instant-runoff-voting,">web.archive.org/web/20131231115533www.fairvote.org/instant-runoff-voting, 31 December 2013,
• WEB,www.lwvofvt.org/files/position_on_voter_rights_and_government.pdf," title="web.archive.org/web/20071128104859www.lwvofvt.org/files/position_on_voter_rights_and_government.pdf,">web.archive.org/web/20071128104859www.lwvofvt.org/files/position_on_voter_rights_and_government.pdf, 28 November 2007, League of Women Voters of Vermont,www.lwvofvt.org/files/position_on_voter_rights_and_government.pdf,
• Ranked Choice Voting at [Represent.Us]
• InstantRunoff.com
• Ranked Ballot Initiative of Toronto, rabit.ca
• www.rooseveltcampusnetwork.org/policy/instant-runoff-voting-national-elections" title="web.archive.org/web/20110727223239www.rooseveltcampusnetwork.org/policy/instant-runoff-voting-national-elections">Roosevelt Institution
• Citizens for Voter Choice :: Massachusetts
• FairVote Minnesota
• www.commoncause.org/site/pp.asp?c=dkLNK1MQIwG&b=4849119" title="web.archive.org/web/20100704143003www.commoncause.org/site/pp.asp?c=dkLNK1MQIwG&b=4849119">Common Cause Massachusetts
• Brookings Institution’s “Empowering Moderate Voters” paper
• Does the Alternative Vote Bring Tyranny to Australia? – Antony Green ABC

Opposition groups and positions

• Center for Election Science compares Instant runoff to Approval voting
• Fair Vote Canada paper on the Alternative Vote
• www.ncvoter.net/downloads/Instant_Runoff_Voting_Value_and_Risks_Report.pdf" title="web.archive.org/web/20070926202415www.ncvoter.net/downloads/Instant_Runoff_Voting_Value_and_Risks_Report.pdf">Instant Runoff Voting Report Values and Risks Report by the N.C. Coalition for Verified Voting

{{voting methods}}{{Parliament of Australia}}{{United Kingdom Alternative Vote referendum, 2011}}