Single Transferable Vote

The Single Transferable Vote (STV) is a proportional electoral system used primarily in the UK in Northern Ireland. STV is often said to be more complicated than some other voting systems. However, it produces a high degree of proportionality whilst also maintaining a strong connection between representatives and their local area.

Under STV, multiple representatives are elected to each constituency (unlike FPTP). So, one area may be choosing four members, for example. Voters rank candidates in order of preference. A quota of votes that a candidate has to reach in order to be elected is determined by dividing the total number of votes by the number of seats available. If a candidate receives more votes than the quota they are elected, and their additional votes are redistributed to the other candidates on the basis of who was put as the next preference. If this process doesn’t fill all the available seats, then the candidate with the least votes is eliminated and their votes are redistributed to whoever their voters put as their second preference. This process is repeated until all the seats in the constituency have been filled.

Proponents of STV say that it allows voters to vote for who they really want, rather than tactically or for the least bad option. They can vote for candidates all from the same party or for individuals from a number of different parties or independent candidates. Furthermore, it is said that constituency boundaries under STV are more in keeping with recognisable town, city, or county distinctions than a system like FPTP, where artificial boundaries are drawn based on population density. However, others argue that STV is complex and less easy to comprehend than FPTP. Nevertheless, its use in the Republic of Ireland, Northern Ireland and for some elections in Scotland indicates that voters are able to get to grips with STV and use the system effectively.

Where is it used?

he Northern Ireland Assembly, European Parliament elections in Northern Ireland, Scottish council elections

How does it work?

· It uses multi-member constituencies; in the case of the Northern Ireland Assembly, there are 17, each returning 6 members.

· Voters number their choices preferentially: 1, 2, 3 etc.

· In order to be elected, a candidate needs to achieve a quota, arrived at using the Droop formula, which divides the number of votes cast by the number of seats contested plus one.

The results are calculated using a complex counting process that takes into account voters' second preferences. If a candidate reaches the quota on the first round of counting, they are elected and their second preferences are redistributed. If no one attains the quota, the least popular candidate is eliminated and the second preferences of those who voted for this candidate are transferred. This process is continued until all the seats are filled.

Scottish council elections


STV gives voters a large choice and allows them to show a preference between candidates of the same party.

Voters have a choice of six representatives when deciding whom they wish to pursue their grievances.

It helps small parties win seats.

The overall outcome is a multi-party system. In Northern Ireland, five different parties win a significant number of seats.

It favours a 'power-sharing system' where all parties have a place in the Assembly and in government. This is essential in a deeply divided society such as Northern Ireland


· There is a close correlation between votes and seats.

· Voter choice is high; it is possible to choose between candidates standing for the same party as well as between candidates from different parties.

· In Northern Ireland it has created a power-sharing government that enables representatives of the two rival communities, the unionists and nationalists, to work together, ending 30 years of violent disturbance in Northern Ireland.


· It is not fully proportional, particularly where smaller multi-member constituencies are used.

· In large multi-member constituencies, the link between the member and the voters may be weak.

· Power-sharing governments may bring rival groups together but they are still prone to conflict. The Northern Ireland executive was suspended several times in its early years, including for almost five years in 2002-07 as a result of a breakdown of trust. Co-operation between the parties broke down again early in 2017, triggering further elections. STV did not help the more centrist parties in the long term. The dominant parties are now the Democratic Unionist Party and republican Sinn Fein. Since 2007 they have replaced the more moderate Ulster Unionist Party and Social and Democratic Labour Party. Voting across community lines is still rare.