Electoral Reform Society

The Single Transferable Vote

An introduction

The Single Transferable Vote (STV) is a form of preferential voting in multi-member constituencies.

Preferential voting means that instead of casting a single vote for a single candidate, a voter can express a list of preferences. Votes are cast by putting a '1' in the column next to the voter's preferred candidate, a '2' beside their second favourite candidate and so on until they no longer wish to express a preference. Voters may vote for candidates within parties and across parties as well as for independents.

A quota is calculated which sets the number of votes a candidate must attain to be elected. This is, simply, the total number of votes cast, divided by one more than the number of candidates to be elected, plus one vote. By following this formula, no more than the required number of candidates can reach the quota.

Votes are counted according to the first preferences and any candidates who have achieved the quota are elected.

To decide which of the remaining candidates are elected the votes are transferred from candidates who have more than the necessary number to achieve the quota and from the candidate with the least number of votes. This means that where the first preferences of the voters were not able to be used to elect a candidate, their second preferences come into play. This process of transferring votes continues until the required number of candidates have attained enough votes to be elected.

The Single Transferable vote is currently used in Northern Ireland for local and European elections.

For an illustration of an election using the Single Transferable Vote, click here.

A rationale

(This is based on an extract from "The Politics of Electoral Reform" by Michael Meadowcroft)

The Single Transferable Vote is so called because it is based on the principle that the elector has a first choice of representative, but if that preferred candidate has either so many votes that the individual's vote is not needed or has the least chance of being elected, then his or her vote is transferred pro rata to a second or subsequent choice. The aim of the system is to give the voter the widest choice possible between candidates whilst eliminating, as far as possible, wasted votes (i.e. all votes which do not help to elect a candidate).

The mathematical formula to implement the principle may initially appear complex, but quickly becomes clear through usage, and operates under rules which have been accepted over decades in both the Republic of Ireland and Northern Ireland.

Because constituencies are multi-member, the number of seats in each one can vary, depending on natural boundaries, so that the artificiality of carving segments out of a city, or tacking odd bits of countryside on to a town to make up the numbers, can be avoided. In Ireland, constituencies elect three, four, or five members. A similar provision of minimum and maximum numbers of seats per constituency could be made for the UK -- preferably with a higher maximum to reflect the larger population concentrations in Britain.

All the major parties have expressed increasing concern at the desperately low representation of women and of ethnic minorities in Parliament. With STV and multi-member constituencies, parties would have a powerful electoral incentive to present a balanced team of candidates in order to maximise the number of higher preferences that would go to their sponsored candidates. It seems unlikely that single-member constituencies will ever depart significantly from adopting the traditional "safe" candidate, thus denying the electors the chance to redress the present parliamentary imbalance.

An argument against multi-member constituencies has been the inherent need to have particularly large constituencies in rural areas. As with every argument on election systems there are genuine difficulties with some aspects of each case. The crucial fact is that the constituency link is retained, albeit between several MPs and an enlarged constituency. The accountability of MPs to their constituency is actually increased in that, unlike British single-member constituencies, no individual MP has a safe seat.

In any case, electors tend to feel a natural link with, say, the City of Leeds as a whole rather than Leeds Central, North East or North West. They may well prefer to have real influence over the MPs representing the whole city rather than pretend to hold the one MP for their sector accountable. Multi-member seats are, of course, the norm for local government where the concept of working as a team for a local ward is often seen to be advantageous.

Under STV, with voters able to express as many preferences as they wish, it is impossible to vote negatively. Parties will inevitably respond to this by developing policies to attract a wider cross-section of support, rather than being able to rely on people voting against one party or another.

The key point about STV is that it reflects proportionally the individual's voting intentions far better than any other system. Every vote has equal value and the number of 'wasted' votes, i.e. those which failed to elect any candidate of the voter's choice, is extremely small. Its ability to empower the voter is its greatest asset, and will reward the best in party politics as much as it will penalise the worst.

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