Instant-runoff voting
Instant-runoff voting (IRV), also known as ranked-choice voting or the alternative vote (AV),[1] combines ranked voting (in which voters rank candidates rather than choosing only a single preferred candidate) together with a system for choosing winners from these rankings by repeatedly eliminating the candidate with the fewest first-place votes and reassigning their votes until only one candidate is left.[2][3] It can be seen as a modified form of a runoff election or exhaustive ballot in which, after eliminating some candidates, the choice among the rest is made from already-given voter rankings rather than from a separate election. Many sources conflate this system of choosing winners with ranked-choice voting more generally, for which several other systems of choosing winners have also been used.
For the proportional electoral system applying ranked ballots to multi-member constituencies, see Single transferable vote.IRV is used in national elections in several countries. In Australia, it is used to elect members of the federal House of Representatives,[4] 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,[5] and the National Parliament of Papua New Guinea,[6] as well as to determine the Academy Award for Best Picture[7] and the Hugo Awards.[8]
Terminology[edit]
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.[12] It is also known as the alternative vote, transferable vote, ranked-choice voting (RCV), single-seat ranked-choice voting, or preferential voting.[13]
Britons and New Zealanders generally call IRV the "alternative vote" (AV).[14][15] Australians, who use IRV for most single winner elections, call IRV "preferential voting".[16] 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.[17][18] As a result of American influence, the term ranked-choice voting is often used in Canada as well.[19] American NGO FairVote has promoted the terminology "ranked-choice voting" to refer to IRV,[19][20] 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[21] (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.[22] State law in South Carolina[23] and Arkansas[24] 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[edit]
Wasted votes and Condorcet winners[edit]
Compared to a plurality voting system that rewards only the top vote-getter, instant-runoff voting mitigates the problem of wasted votes.[25] 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:
Criticism[edit]
Voter confusion and legitimacy of elections[edit]
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.[53] 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.[54]
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".[55] 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".[56] Federal judge Lance Walker rejected this claim, and the 1st circuit court denied Poliquin's emergency appeal, leading to Poliquin dropping his claim.[57]
Similarity to plurality[edit]
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.[58]
Participation[edit]
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:[59]
The report concluded:[60]
Similar methods[edit]
Runoff voting[edit]
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.[71] 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.