Contingent vote - AbsoluteAstronomy.com

The contingent vote is an electoral system

Voting system

A voting system or electoral system is a method by which voters make a choice between options, often in an election or on a policy referendum....

used to elect a single winner, in which the voter ranks the candidates in order of preference. In an election, if no candidate receives an absolute majority of first preference votes, then all but the two leading candidates are eliminated and there is a second count. In the second count the votes of those who supported eliminated candidates are distributed among the two remaining candidates, so that one candidate achieves an absolute majority. The contingent vote is similar to the alternative vote but differs from it in that the alternative vote typically allows for many rounds of counting, whereas under the contingent vote there are never more than two. In the United States both the contingent vote and the alternative vote are often referred to as variants of instant-runoff voting

Instant-runoff voting

Instant-runoff voting , also known as preferential voting, the alternative vote and ranked choice voting, is a voting system 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...

. The contingent vote can also be considered a compressed form of the two round system (runoff system), in which both 'rounds' occur without the need for voters to go to the polls twice.

Today a special variant of the contingent vote is used to elect the President of Sri Lanka

President of Sri Lanka

The President of Democratic Socialist Republic of Sri Lanka is the elected head of state and the head of government. The President is a dominant political figure in Sri Lanka. The office was created in 1978 but has grown so powerful there have been calls to restrict or even eliminate its power...

. Another variant, called the supplementary vote, is used to elect mayors in England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

. In the past the ordinary form of the contingent vote was used to elect the Queensland Legislative Assembly

Queensland Legislative Assembly

The Queensland Legislative Assembly is the unicameral chamber of the Parliament of Queensland. Elections are held approximately once every three years. Voting is by the Optional Preferential Voting form of the Alternative Vote system...

from 1892 to 1942. To date, this has been the longest continuous use of the system anywhere in the world. It was also used in the U.S.

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

state of Alabama

Alabama

Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...

in the 1920s.

Voting and counting

In an election held using the contingent vote the voters rank the list of candidates in order of preference. Under the most common ballot layout, they place a '1' beside their most preferred candidate, a '2' beside their second most preferred, and so on. In this respect the contingent vote is the same as instant-runoff voting.

There are then a maximum of two rounds of counting. In the first round only first preferences are counted. If a candidate has received an absolute majority of first preferences (i.e. more than half) then he is immediately declared the winner. However if no candidate has an absolute majority then all but the two candidates with the most first preferences are eliminated, and there is a second round. In the second round the votes of the voters whose first preference had been eliminated are transferred to whichever of the two remaining candidates were ranked the highest. The votes are then counted and whichever candidate has an absolute majority is declared elected.

Example I

Imagine an election in which there are three candidates: Andrew, Brian and Catherine. There are 100 voters and they vote as follows (third preferences are omitted):

#	30 voters	6 voters	9 voters	7 voters	28 voters	20 voters
1st	Andrew	Andrew	Brian	Brian	Catherine	Catherine
2nd	Brian	Catherine	Andrew	Catherine	Brian	Andrew

1. To begin the count first preferences are counted, and the tallies stand at:

Andrew: 36
Brian: 16
Catherine: 48

2. No candidate has an absolute majority of votes (this would be 51), so the two candidates with most votes proceed to a second round and Brian, who has the fewest votes, is excluded. 9 of Brian's supporters have given Andrew as their second preference, and 7 have given Catherine as their second preference, so these votes transfer to Andrew and Catherine respectively. The tallies then become:

Andrew: 45
Catherine: 55

Result: Catherine has the most votes so is declared the winner.

Example II

Imagine another election in which there are four candidates: Andrea, Brad, Carter and Delilah. There are 120 voters and they vote as follows (fourth preferences are omitted):

#	34 voters	17 voters	22 voters	10 voters	37 voters
1st	Andrea	Brad	Carter	Carter	Delilah
2nd	Brad	Carter	Brad	Delilah	Carter
3rd	Carter	Andrea	Andrea	Brad	Brad

The count would proceed as follows:

Round 1: First preferences are tallied and no candidate has a majority (in this election an absolute majority would be 61).
Round 2: Andrea and Delilah have the most votes so they proceed to a second round while Brad and Carter are excluded. The votes of Brad and Carter supporters are now distributed among the two survivors. To do this the ballot papers of Brad and Carter supporters are examined to see which of the two remaining candidates each voter has ranked higher. The preferences expressed on the ballot papers of Brad and Carter supporters were as follows:

#	17 voters	22 voters	10 voters
1st	Brad	Carter	Carter
2nd	Carter	Brad	Delilah
3rd	Andrea	Andrea	Brad
4th	Delilah	Delilah	Andrea

On the basis of these ballot papers 39 votes are transferred to Andrea and 10 to Delilah.

Winner: Once Brad and Carter's votes have been transferred Andrea has a majority of votes and so is the winner.

Variants

The Supplementary Vote and Sri Lankan contingent vote are two implemented variation in which voters, unlike ordinary form of the contingent vote, cannot rank all of the candidates, but rather are only permitted to express two and three preferences respectively.

This means that if a voter does not use either of his preferences to support one of the candidates who survives to the second round then it will be impossible to transfer his vote, which is therefore 'wasted' or 'exhausted'.

Supplementary Vote

Under the Supplementary Vote, voters express a first and second choice of candidate only, and, if no candidate receives an absolute majority of first choice votes, all but the two leading candidates are eliminated and the votes of those eliminated redistributed according to their second choice votes to determine the winner. The Supplementary Vote is currently used in all elections for directly elected mayors in England

England

, including the Mayor of London

Mayor of London

The Mayor of London is an elected politician who, along with the London Assembly of 25 members, is accountable for the strategic government of Greater London. Conservative Boris Johnson has held the position since 4 May 2008...

History and current use

In the early 1990s, the Plant Commission was established by the Labour Party

Labour Party (UK)

The Labour Party is a centre-left democratic socialist party in the United Kingdom. It surpassed the Liberal Party in general elections during the early 1920s, forming minority governments under Ramsay MacDonald in 1924 and 1929-1931. The party was in a wartime coalition from 1940 to 1945, after...

, which was then in opposition, to recommend a new voting system for the Parliament of the United Kingdom

Parliament of the United Kingdom

The Parliament of the United Kingdom of Great Britain and Northern Ireland is the supreme legislative body in the United Kingdom, British Crown dependencies and British overseas territories, located in London...

. When the Commission reported in 1993, instead of suggesting an already existing system, it recommended the Supplementary Vote (SV) system, which had never been used anywhere. Although some commentators credit the invention of SV to Plant, it was actually the brainchild of the then Labour Member of Parliament

Member of Parliament

A Member of Parliament is a representative of the voters to a :parliament. In many countries with bicameral parliaments, the term applies specifically to members of the lower house, as upper houses often have a different title, such as senate, and thus also have different titles for its members,...

(MP) for Workington

Workington

Workington is a town, civil parish and port on the west coast of Cumbria, England, at the mouth of the River Derwent. Lying within the Borough of Allerdale, Workington is southwest of Carlisle, west of Cockermouth, and southwest of Maryport...

, Dale Campbell-Savours, who advocated and outlined it in an article he wrote for an issue of the left-leaning New Statesman
New Statesman
New Statesman is a British centre-left political and cultural magazine published weekly in London. Founded in 1913, and connected with leading members of the Fabian Society, the magazine reached a circulation peak in the late 1960s....

magazine that was published four years before Plant reported, on September 29, 1989.

However, it never became official Labour Party policy to introduce SV for national elections in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

. Prior to 2000, there were no directly elected mayors in England but, when direct elections were introduced for some mayors, it was decided to use SV and it is now in use for the direct election of eleven English mayors, including the Mayor of London

Mayor of London

Voting and counting

There are two methods in which a vote can be cast.

Two columned ballot paper	Single columned ballot paper
Each voter ranks at least one and no more than two candidates by placing an 'X' in one column to indicate his or her first choice of candidate and another 'X' in a second column to indicate his or her second choice of candidate. In the first round of counting only first preferences are tallied. If any candidate has an absolute majority of votes (i.e. more than half) at this stage then they are declared elected. If no candidate has a majority then all candidates except the two with most first preferences are eliminated and the count proceeds to a second round. In the second round any voter whose first preference has been eliminated has his vote transferred to the candidate of his second preference (but only if his second choice has not also been eliminated). The candidate with the most votes is then declared elected.	A less common form is to print a single column on the ballot paper and require voters to write '1' next to their first preference and '2' next to their second. This form was used to elect the Mayor of Newham London Borough of Newham The London Borough of Newham is a London borough formed from the towns of West Ham and East Ham, within East London.It is situated east of the City of London, and is north of the River Thames. According to 2006 estimates, Newham has one of the highest ethnic minority populations of all the... in the 2006 election United Kingdom local elections, 2006 Local government elections took place in England on Thursday 4 May 2006. Polling stations were open between 7:00 and 22:00.All London borough council seats were up for election, as well as a third of the seats on each of the metropolitan borough councils, and a third of some unitary authorities... .

Impact on factions and candidates

The Supplementary Vote is said to encourage candidates to seek support beyond their core base of supporters in order to secure the second preferences of the supporters of other candidates and so to create a more conciliatory campaigning style among candidates with similar policy platforms. SV is also likely to improve the chances of 'third party' candidates by encouraging voters who wish to do so to vote sincerely for such candidates where under systems such as 'first past the post' they would be discouraged from doing so for tactical reasons.

These potentially positive effects will be moderated, however, by the strong incentives SV creates for voting, in most circumstances, for only candidates from among the leading three. The Electoral Reform Society

Electoral Reform Society

The Electoral Reform Society is a political pressure group based in the United Kingdom which promotes electoral reform. It is believed to be the oldest organisation concerned with electoral systems in the world.-Aims:...

criticised SV following the mayoral election in Torbay

Torbay

Torbay is an east-facing bay and natural harbour, at the western most end of Lyme Bay in the south-west of England, situated roughly midway between the cities of Exeter and Plymouth. Part of the ceremonial county of Devon, Torbay was made a unitary authority on 1 April 1998...

in October 2005, claiming that 43.5% of second preference votes were ignored as not being given to either of the top two placed candidates, disadvantaging supporters of non-party candidates.

Rallings et al. have noted two important flaws of SV:

First, since the automatic dual-ballot nature of SV dispenses with any need for a runoff two weeks later - as often happens for, say, the election of the president of France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

- voters go in casting their second preferences with little or no idea of which candidates will make the runoff. Consequently, many second preferences will be declared invalid because they have been cast for eliminated candidates. It could be said here, of course, that a cursory look at opinion polls taken during the campaign would give voters an informed idea of which candidates are the front-runners; however not all elections using the system have opinion polls conducted and published.

Second, it is possible for the victor to fail to achieve an absolute majority overall, i.e. in terms of the total first and second preference votes, since it is not an obligation for a voter to cast a second preference and, moreover, a second preference will be ineffective unless it is cast for a candidate who makes it into the top two. They argue that this is important as victors may still claim, in such cases, to have won a clear majority mandate from the voters when, in fact, they have not. They remark further: 'It is perhaps surprising that the [British] government did not opt for AV [the Alternative Vote], which requires only a single ballot and guarantees a majority winner'.

Like other forms of the Contingent Vote, the Supplementary Vote is not a form of proportional representation

Proportional representation

Proportional representation is a concept in voting systems used to elect an assembly or council. PR means that the number of seats won by a party or group of candidates is proportionate to the number of votes received. For example, under a PR voting system if 30% of voters support a particular...

and so, were it used to elect a council or legislature, it could be expected to produce results similar to other systems involving single seat constituencies such as the 'first past the post

Plurality voting system

The plurality voting system is a single-winner voting system often used to elect executive officers or to elect members of a legislative assembly which is based on single-member constituencies...

' (plurality) system.

Sri Lankan contingent vote

In Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

a variant of the contingent vote electoral system

Voting system

A voting system or electoral system is a method by which voters make a choice between options, often in an election or on a policy referendum....

is used to elect the President

President of Sri Lanka

. As under the conventional contingent vote, in an election held using the Sri Lankan form of the contingent vote each voter ranks the candidates in order of preference, and if no candidate receives an overall majority of first preference votes on the first count then all but the two leading candidates are eliminated and their votes redistributed to help determine a winner in a second and final round. However, whereas under the ordinary form of the contingent vote voters can rank all of the candidates in order of preference, under Sri Lankan CV the voter only expresses his or her top three preferences. Sri Lankan CV has been used for presidential elections there since 1982.

Two round system

Under the two round system (also known as 'runoff voting' and the 'second ballot') voters vote for only a single candidate, rather than ranking candidates in order of preference. As under the contingent vote, if no candidate has an absolute majority in the first round, all but the top two are eliminated and there is a second round. However, in the two round system, voters are asked to return and vote a second time. Because of the similarities between them, the contingent vote and the two round system can usually be expected to elect the same winner. However in the two round system, the voter is permitted to change one's mind from one round to another, even if the favourite candidate in the first round has not been eliminated.

The Alternative Vote

As noted above, the alternative vote differs from the contingent vote in that it permits several rounds rather than just two. Under the alternative vote only one candidate is eliminated after each round, and as many rounds occur as are necessary to give one candidate an absolute majority. These differences mean that the contingent vote and alternative vote can produce different results. Because, under the contingent vote, all but two candidates are eliminated in the first round, it is possible for a candidate to be eliminated who would have gone on to win had he been allowed to receive transfers in later rounds.

Example

If the election in Example II had been conducted using IRV instead of the contingent vote then the winner would have been Carter rather than Andrea. This is because the election would have proceeded as follows:

Round 1: First preferences are tallied and no candidate has a majority.
Round 2: Under IRV only one candidate is now eliminated. This is Brad, as he has the fewest votes. His votes all transfer to Carter.
Round 3: There is still no candidate with an absolute majority. Now Andrea has the fewest votes so she is eliminated. Her votes all transfer to Carter, who then has an absolute majority.
Winner: After three rounds, Carter is elected.

Note: Arrow's impossibility theorem

Arrow's impossibility theorem

In social choice theory, Arrow’s impossibility theorem, the General Possibility Theorem, or Arrow’s paradox, states that, when voters have three or more distinct alternatives , no voting system can convert the ranked preferences of individuals into a community-wide ranking while also meeting a...

demonstrates that no voting system based on ranked preferences can possibly meet a certain set of reasonable criteria when there are three or more candidates to choose from. In the above example, it is as possible that Andrea could be a stronger majority compromise candidate

Condorcet criterion

The Condorcet candidate or Condorcet winner of an election is the candidate who, when compared with every other candidate, is preferred by more voters. Informally, the Condorcet winner is the person who would win a two-candidate election against each of the other candidates...

, able to win an absolute majority against Carter head-to-head and also beat and Delilah head-to-head, which IRV can not recognize by its sequential elimination. Contingent vote treats the top two candidates equally, and like plurality

Plurality voting system

The plurality voting system is a single-winner voting system often used to elect executive officers or to elect members of a legislative assembly which is based on single-member constituencies...

, it can predictably reward the strongest candidates, those who are selected as first choice among the most voters.

Tactical voting

Like virtually all electoral systems (see the Gibbard-Satterthwaite theorem

Gibbard-Satterthwaite theorem

The Gibbard–Satterthwaite theorem, named after Allan Gibbard and Mark Satterthwaite, is a result about the deterministic voting systems that choose a single winner using only the preferences of the voters, where each voter ranks all candidates in order of preference...

), the contingent vote is open to tactical voting

Tactical voting

In voting systems, tactical voting occurs, in elections with more than two viable candidates, when a voter supports a candidate other than his or her sincere preference in order to prevent an undesirable outcome.It has been shown by the Gibbard-Satterthwaite theorem that any voting method which is...

. In particular, like both the two round system and instant-runoff voting, it is vulnerable to the tactics of 'push-over' and 'compromise'. Under the contingent vote compromising occurs where a voter gives a first or other high preference to a candidate not because they necessarily support them, but as a way of avoiding the election of a candidate who they dislike even more. The contingent vote is more vulnerable to compromising than IRV. In the first example given in this article if a large number of Catherine supporters had 'compromised', and given a first preference to Brian, then Brian would have been elected instead of Andrew, a candidate who Catherine supporters dislike even more. This tactic would have been effective under IRV as well as the contingent vote. In Example II Brad supporters, had they predicted that Brad would not make it to the second round, could have compromised by giving their first preferences to Carter, and thereby have ensured his election. This would not have been a necessary tactic under IRV because the votes of Brad supporters would have ended up with Carter anyway—when Brad was eliminated they would have transferred to him.

However the contingent vote is less vulnerable to the tactic of compromise than the 'first-past-the-post

Plurality voting system

The plurality voting system is a single-winner voting system often used to elect executive officers or to elect members of a legislative assembly which is based on single-member constituencies...

' (plurality) system. This is because the contingent vote's system of transferring votes means that even if a voter's first choice is unlikely to be elected, her vote may still have a chance to be transferred to one of her subsequent preferences. In Example I above Catherine would have won under the plurality system because she has more votes than any other candidate. However Brian voters would have been able to ensure the election of their second choice, Andrew, by voting tactically for Andrew instead of Brian. This tactic is not necessary under the contingent vote because the votes of Brian supporters will transfer to Andrew in the second round anyway.

'Push-over' is a tactic by which a voter insincerely ranks an unpopular 'push-over' candidate higher than her real first choice. The purpose of voting for the 'push-over' is to ensure that it is this weak candidate, rather than a more popular rival, who remains to challenge her preferred candidate in the second round. By supporting a push-over candidate it is hoped to eliminate a stronger candidate who might have gone on to win the election. Under the contingent vote a voter uses the tactic by giving her first preference to a 'push over' and her lower preferences to the candidates she really supports.

The push-over tactic requires voters to be able to reliably predict how others will vote. It runs the risk of backfiring, because if the tactical voter miscalculates then the candidate intended as a push-over might end up actually beating the voter's preferred candidate. It also requires voters to understand the tactic and be aware that it exists. For these reasons some doubt that push-over is likely to be a factor in real elections. Because under the contingent vote, as under IRV, it is paradoxically possible to harm the chances of a candidate by giving them a first preference, or to aid the chances of a candidate by ranking them lower than first, the system is said to fail the monotonicity criterion

Monotonicity criterion

The monotonicity criterion is a voting system criterion used to analyze both single and multiple winner voting systems. A voting system is monotonic if it satisfies one of the definitions of the monotonicity criterion, given below.Douglas R...

Strategic nomination

The contingent vote can be influenced by the same forms of strategic nomination

Strategic nomination

Strategic nomination is the manipulation of an election through its candidate set...

as IRV and the two round system. Strategic nomination is where candidates and political factions influence the result of an election by either nominating extra candidates or withdrawing a candidate who would otherwise have stood. The contingent vote is vulnerable to strategic nomination for the same reasons that it is open to the voting tactic of 'compromising'. This is because it is sometimes necessary for a candidate who knows they are unlikely to win to ensure that another candidate he supports makes it to the second round by withdrawing from the race before the first round occurs, or by never choosing to stand in the first place. By withdrawing candidates a political faction can avoid the 'spoiler effect

Spoiler effect

The spoiler effect describes the effect a minor party candidate with little chance of winning has in a close election, when that candidate's presence in the election draws votes from a major candidate similar to them, thereby causing a candidate dissimilar to them to win the election...

', whereby a candidate 'splits the vote' of her supporters and prevents any candidate acceptable to them from surviving to the last round. For instance, in Example I above, if Catherine had chosen not to stand then Brian would have been elected instead of Andrew, a more desirable result for Catherine's supporters. However the contingent vote's system of transfers makes it less vulnerable to the spoiler effect than the plurality system.

Impact on factions and candidates

Like IRV and the two round system, the contingent vote is said to encourage candidates to seek support beyond their core base of supporters in order to secure the lower preferences of the supporters of other candidates. This is said to create a more conciliatory campaigning style among candidates with similar policy platforms. However this effect will be diminished by the fact that lower preferences are less important under the contingent vote than under IRV; under the contingent vote it is especially important for candidates to receive many first preferences so that they are not eliminated straight away.

The contingent vote is not a form of proportional representation

Proportional representation

, and therefore, if used to elect a council or legislature, it overrepresents larger parties at the expense of smaller ones, and encourages a two party system, in the same manner as other systems based on single seat constituencies (districts), such as 'first past the post', instant run-off and the two round system. However the contingent vote does aid the chances of 'third party' candidates to some extent, by encouraging voters who wish to do so to vote sincerely for such candidates where under 'first past the post' they would be discouraged from doing so for tactical reasons.

External links

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Voting and counting

Example I

Example II

Variants

Supplementary Vote

History and current use

Voting and counting

Impact on factions and candidates

Sri Lankan contingent vote

Two round system

The Alternative Vote

Example

Tactical voting

Strategic nomination

Impact on factions and candidates

See also

External links