Sample ballot paper

The Supplementary Vote (SV) is an electoral system used fore the election of a single candidate. It is a variant of the Contingent 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 on the first count, all but the two leading candidates are eliminated and their votes redistributed to help determine a winner in a second and final round. The Supplementary Vote is currently used in all elections for directly elected mayors in England, including the Mayor of London. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The contingent vote is an electoral system used to elect a single winner, in which the voter ranks the candidates in order of preference. ... For other uses, see England (disambiguation). ... Ken Livingstone, the current Mayor of London The Mayor of London is an elected politician in London, United Kingdom. ...

Voting and counting

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

Two 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.

Single columned ballot paper

Another possible style of ballot paper

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 in the 2006 election. Image File history File links Supplementary_Vote_ballot_paper. ... Image File history File links Supplementary_Vote_ballot_paper. ... This article is about the London borough. ... Local government elections took place in England (only) on Thursday 4 May 2006. ...

Example

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

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. All of Brian's supporters have given Andrew as their second preference, so his votes all transfer to Andrew. The tallies then become:

• Andrew: 52
• Catherine: 48

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

Comparison with similar systems

As noted above, the Supplementary Vote is a variant of the Contingent Vote system, but under SV voters are permitted to rank only two candidates, whereas under the Contingent Vote, they can rank all of them. Both SV and the conventional Contingent Vote also differ from instant run-off voting (IRV). In IRV rather than only two rounds there are many; only one candidate is eliminated after each round, and as many rounds occur as are necessary to produce a winner. These differences mean that SV, the conventional Contingent Vote, and IRV can all produce different results when more than 3 candidates are running for election. Like the Contingent Vote and IRV this method fails the monotonicity criterion. When the single transferable vote voting system is applied to a single-winner election it is sometimes called instant-runoff voting (IRV), as it is much like holding a series of runoff elections in which the lowest polling candidate is eliminated in each round until someone receives majority vote. ... A voting system is monotonic if it satisfies the monotonicity criterion, given below. ...

Under the Supplementary Vote restricting a voter to two preferences means that it might not be possible to transfer her vote to any candidate in the final round–if this occurs her vote is said to be 'exhausted'. If voters are permitted to rank all of the candidates then this cannot occur and every voter will have a chance to contribute to electing a winner in the final round. Because of this SV and the conventional Contingent Vote often produce a different winner. 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. This fact differentiates all forms of the Contingent Vote from IRV.

Example

Imagine an election in which there are four candidates: Andrea, Brad and Carter and Delilah. There are 100 voters. If they were asked to rank all of the candidates in order of preference then their preferences would be as follows:

However under the Supplementary Vote the voters are permitted to express only their top two preferences, so they vote as follows:

1. To begin the count first preference votes would be tallied, and found to be as follows:

• Andrea: 47
• Brad: 20
• Carter: 18
• Delilah: 15

2. No candidate has an absolute majority so Andrea and Brad would proceed to the second round, while the other two would be excluded. Carter supporters all have Brad as their second choice so their votes would now transfer to Brad. However Delilah voters have Carter as their second choice so, because he is no longer in the count, their votes cannot be transferred to anyone. After the second count the results are therefore:

• Andrea: 47
• Brad: 38

Result: Andrea has the most votes so is the winner.

In the example the result is affected by the fact that Delilah supporters are allowed to express only two preferences; therefore, their votes cannot be transferred to either of the two candidates in the last round. The third preference of Delilah supporters was for Brad. If this preferences had been taken into account then Delilah's votes would have transferred to Brad in the final round and Brad would have been the winner instead of Andrea. For the reason given if the conventional form of the Contingent Vote had been used in the example instead of SV then Brad would have been elected.

The example is also influenced by the fact that there are only two rounds. If IRV were used in the example, instead of either form of the Contingent Vote, then Carter would have been elected. This is because after the first round, only Delilah would have been eliminated. His votes would then transfer to Carter and the tallies would become:

• Andrea: 47
• Brad: 20
• Carter: 33

Brad would then be eliminated and his votes would transfer to Carter, who would then have an absolute majority of votes.

History and current use

The Supplementary Vote has been used since 2000 to elect the Mayor of London. At the start of the twenty-first century it was also in use for the direct election of eleven English mayors. The Plant Commission was established by the Labour Party, which was then in opposition, to recommend a new voting system for the Parliament of the United Kingdom. When the Commission reported in 1993, instead of suggesting an already existing system, it recommended SV, which had hitherto not 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 (MP) for Workington, Dale Campbell-Savours, who advocated and outlined it in an article he wrote for an issue of the left-leaning New Statesman 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. Prior to 2000 there were no directly elected mayors in England. When direct elections were introduced for some mayors it was decided to use SV. Year 2000 (MM) was a leap year starting on Saturday (link will display full 2000 Gregorian calendar). ... Ken Livingstone, the current Mayor of London The Mayor of London is an elected politician in London, United Kingdom. ... The Labour Party is a political party in the United Kingdom. ... Type Bicameral Houses House of Commons House of Lords Speaker of the House of Commons Michael Martin MP Lord Speaker Hélène Hayman, PC Members 1377 (646 Commons, 731 Peers) Political groups Labour Party Conservative Party Liberal Democrats Scottish National Party Plaid Cymru Democratic Unionist Party Sinn Féin... Year 1993 (MCMXCIII) was a common year starting on Friday (link will display full 1993 Gregorian calendar). ... A Member of Parliament, or MP, is a representative elected by the voters to a parliament. ... , Workington is a town and port on the west coast of Cumbria, England at the mouth of the River Derwent. ... Dale Norman Campbell-Savours, Baron Campbell-Savours (born 31 August 1943) is a politician in the United Kingdom. ... The New Statesman is a left-of-centre political weekly published in London. ... is the 272nd day of the year (273rd in leap years) in the Gregorian calendar. ... Year 1989 (MCMLXXXIX) was a common year starting on Sunday (link displays 1989 Gregorian calendar). ... Year 2000 (MM) was a leap year starting on Saturday (link will display full 2000 Gregorian calendar). ...

A system similar to the SV has been used to elect the President of Sri Lanka since 1982. Under the Sri Lankan system voters are permitted to express, from among the list of candidates, not just a first and second but also a third preference. The President of Sri Lanka is the head of state and dominant political figure in Sri Lanka. ... Year 1982 (MCMLXXXII) was a common year starting on Friday (link displays the 1982 Gregorian calendar). ... In Sri Lanka a system that may be considered a variant of the Supplementary Vote (SV) is used to elect the president. ...

Potential for tactical voting

The Supplementary Vote is open to the same forms of tactical voting as other forms of the Contingent Vote. These include the tactics of 'compromise' and 'push over'. However the fact that voters are permitted to express only two preferences makes it especially vulnerable to 'compromise'. This is because it makes it necessary for voters to express either a first or a second preference for one of the two leading candidates if they wish to influence the result of the election. If lower preferences were allowed then the voter would, in many circumstances, be able to give her first two preferences to her two favourite candidates, even if neither was likely to be elected; if both had only minor support, then the voter could still influence the election by using her third or subsequent preferences to support more popular candidates. In voting systems, tactical voting (or strategic voting) occurs when a voter supports a candidate other than his or her sincere preference in order to prevent an undesirable outcome. ... The contingent vote is an electoral system used to elect a single winner, in which the voter ranks the candidates in order of preference. ...

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 criticised SV following the mayoral election in Torbay 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^[1]. The Electoral Reform Society is a campaign group based in the UK which promotes electoral reform. ... Torbay (IPA: ) is an east-facing bay, at the western most end of Lyme Bay in the south-west of England, situated roughly midway between the cities of Exeter and Plymouth. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...

Rallings et al have noted two important flaws of SV:^[2]

• 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 - 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.

• Second, it is possible for the victor to fail to achieve an absolute majority overall, i.e., in terms of the total first-preference votes: it is not an obligation for a voter to cast a second preference. 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' (Rallings et al, 2002: 78).

Like other forms of the Contingent Vote, the Supplementary Vote is not a form of proportional representation 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) system. When the single transferable vote voting system is applied to a single-winner election it is sometimes called instant-runoff voting (IRV), as it is much like holding a series of runoff elections in which the lowest polling candidate is eliminated in each round until someone receives majority vote. ... Proportional representation (sometimes referred to as full representation, or PR), is a category of electoral formula aiming at a close match between the percentage of votes that groups of candidates (grouped by a certain measure) obtain in elections and the percentage of seats they receive (usually in legislative assemblies). ... An example of a plurality ballot. ...

Note

1. ^ See Electoral Reform Society press release on Torbay election
2. ^ Colin Rallings, Michael Thrasher and David Cowling (2002), 'Mayoral Referendums and Elections', Local Government Studies 28 (4), pp67-90.

See also

• Elected mayors in the United Kingdom
• List of democracy and elections-related topics

Direct election In 2000 the Labour government led by Tony Blair passed a local government reform which changed this somewhat. ... Politics is the process and method of gaining or maintaining support for public or common action: the conduct of decision-making for groups. ...

External links

• LondonElects: How the Mayor of London is Elected
• Electoral Systems Index: Sri Lanka