Overview: The single transferable vote (STV) combines elements of different systems to both achieve a relatively proportional result and to elect MPs from specific constituencies. It has ranked ballots and large ridings, each with multiple elected MPs.
What family does it belong to? Semi-proportional.
Where is it used today? Two countries use STV to elect their lower houses of government: Ireland and Malta.
How does the system work for voters? Voters rank candidates in order of preference. They can vote for candidates from a variety of parties or from a single party. Some forms of STV require voters to rank all candidates, while others make it optional. By the time all seats from the riding are assigned, nearly all electors’ votes will have counted towards the election of a candidate, producing a relatively proportional result. The result tends to grow more proportional with larger ridings that have more MPs.
What do ridings look like? STV features multiple member constituencies, with the number of MPs in each riding decided when the system is introduced (e.g., this would likely be between three and seven MPs). Accordingly, ridings are bigger than they are in systems that elect only one MP per riding.
How are the ballots counted? To be elected, a candidate must receive a certain quota: a number of votes required to win calculated using the number of votes cast in the riding and the number of seats to be won there. Candidates who reach the quota are elected and become MPs. Excess votes beyond that quota are transferred to the next choice on voters’ ballots. If no candidate has reached the quota, the last-place candidate is eliminated, and their votes are transferred to remaining candidates. Counting continues in this way through subsequent rounds until each seat is filled. This process can take many rounds to complete and cannot begin until all votes are counted. Therefore the results may not be known for some time after voting closes.
How are Parliament and government formed? How is the prime minister selected? The combination of multi-member districts and a quota-based electoral formula ensures the results are broadly proportional across the entire country. If any party receives more than half the seats, the governor general invites its leader to form a government. More often, no single party has a majority, and two or more parties come together to form a coalition. The prime minister is usually the leader of the largest party in the coalition.
Also known as: STV
What does it mean…
1. For campaigning? Campaigning is split between the national race and the local races across the country. A unique feature of the STV system is the power it gives to voters to choose among candidates within each party. This means local races can attract significant voter and media attention. Candidates must work not only to distinguish themselves from the candidates from other parties, but also from others competing to represent the same party in the same riding. They want to help their party win as many seats as possible, while also ensuring they are ranked highly by their parties’ supporters. Parties still have control the nomination process and who runs as their party candidates, but voters have the final say over which candidates get into parliament from each party in a given riding.
2. For vote choice? Given the option to rank all candidates, voters have considerable choice. They may prefer to support a single party or candidates from different parties or independents. In exchange for giving voters the ability to express nuanced preferences, STV asks voters to become familiar with many candidates from multiple parties.
3. For local representation? Multiple MPs per district can weaken the line of responsibility between MPs and the voters they represent. However, there is local representation. In providing proportional results, STV makes it easier for voters to point to a specific MP or party that represents their perspective and candidates often win by attracting local support. Given the need for larger ridings, there are questions on how to represent sparsely populated areas of the country. Either huge geographical ridings could be created in northern and some rural areas, or such areas could elect fewer MPs per riding than elsewhere. At the extreme, less populated areas might remain as single member ridings, with MPs effectively elected by the alternative vote (AV) method.
4. For parties in Parliament? In general, STV produces seat allocations relatively proportional to parties’ share of the vote. As districts grow smaller, overall proportionality is moderated as it becomes more difficult for smaller parties to win seats. Thus, by limiting the number of MPs elected by riding, STV can be designed to limit the number of parties represented in the House.
Due to competition between candidates from the same party to win a seat, party discipline in the House of Commons may be reduced as MPs exercise greater independence to distinguish themselves among their own party colleagues and future MP candidates.
Parties may promote a slate of candidates that increase the representation of women, visible minorities and other diverse Canadians in Parliament, but the makeup of the legislature ultimately remains in the hands of voters choosing between candidates.
5. For governing? Many forms of government are possible under STV, though typically no single party will win a majority of seats; in such cases a minority government or coalition government will form. Under STV party leaders have an incentive to forge alliances with other parties before an election is held, because the ranked ballot allows party supporters to rank candidates from allied parties higher. Even so, some parties may prefer to wait until after the results are known before agreeing to cooperate. Regardless, voters may not know which parties will be in government, even after election results are announced. Additionally, governments may change when coalitions break down.
What would the ballot look like?