Proportional representation (PR) refers to any type of electoral system under which subgroups of an electorate are reflected proportionately in the elected body. The concept applies mainly to political divisions among voters. The essence of such systems is that all votes cast – or almost all votes cast – contribute to the result and are effectively used to help elect someone – not just a bare plurality or (exclusively) the majority – and that the system produces mixed, balanced representation reflecting how votes are cast.
Party-list proportional representation (list-PR) is a subset of proportional representation electoral systems in which multiple candidates are elected through their position on an electoral list. They can also be used as part of mixed-member electoral systems.
The single transferable vote (STV), sometimes known as proportional ranked choice voting (P-RCV), is a multi-winner electoral system in which each voter casts a single vote in the form of a ranked-choice ballot. Voters have the option to rank candidates, and their vote may be transferred according to alternate preferences if their preferred candidate is eliminated or elected with surplus votes, so that their vote is used to elect someone they prefer over others in the running. STV aims to approach proportional representation based on votes cast in the district where it is used, so that each vote is worth about the same as another. Formally, STV satisfies a fairness criterion known as proportionality for solid coalitions.
The electoral threshold, or election threshold, is the minimum share of all the votes cast that a candidate or political party requires to achieve before they become entitled to representation or additional seats in a legislature. This limit can operate in various ways, e.g. in party-list proportional representation systems where an electoral threshold requires that a party must receive a specified minimum percentage of votes, either nationally or in a particular electoral district, to obtain seats in the legislature. In single transferable voting, the election threshold is called the quota and it is possible to pass it by use of first choice votes alone or by a combination of first choice votes and votes transferred from other candidates based on lower preferences. In mixed-member-proportional (MMP) systems the election threshold determines which parties are eligible for top-up seats in the legislative body.
The D'Hondt method, also called the Jefferson method or the greatest divisors method, is an apportionment method for allocating seats in parliaments among federal states, or in proportional representation among political parties. It belongs to the class of highest-averages methods.
The electoral system of Australia comprises the laws and processes used for the election of members of the Australian Parliament and is governed primarily by the Commonwealth Electoral Act 1918. The system presently has a number of distinctive features including compulsory enrolment; compulsory voting; majority-preferential instant-runoff voting in single-member seats to elect the lower house, the House of Representatives; and the use of the single transferable vote proportional representation system to elect the upper house, the Senate.
Electoral systems of the Australian states and territories are broadly similar to the electoral system used in federal elections in Australia.
In electoral systems which use ranked voting, a donkey vote is a cast ballot where the voter ranks the candidates based on the order they appear on the ballot itself. The voter that votes in this manner is referred to as a donkey voter.
In electoral systems, a wasted vote is any vote that does not receive representation in the final election outcome. Plurality voting systems have the greatest number of wasted votes.
The single transferable vote (STV) is a proportional representation voting system that elects multiple winners. It is one of several ways of choosing winners from ballots that rank candidates by preference. Under STV, an elector's vote is initially allocated to their most-preferred candidate. Candidates are elected (winners) if their vote tally reaches quota. After this 1st Count, if seats still remain open, surplus votes are transferred from winners to remaining candidates (hopefuls) according to the surplus ballots' next usable back-up preference. if no surplus votes have to be transferred, then the least-popular candidate is eliminated so the vote has chance to be placed on a candidate who can use it.
One of the ways in which ranked voting systems vary is whether an individual vote must express a minimum number of preferences to avoid being considered invalid. Possibilities are:
Elections to the 1989 Australian Capital Territory Legislative Assembly was held on Saturday, 4 March. This was the first direct election by voters in the Australian Capital Territory (ACT) for their power legislative body.
There are a number of complications and issues surrounding the application and use of single transferable vote proportional representation that form the basis of discussions between its advocates and detractors.
Scotland uses different electoral systems for elections to Parliament, the Scottish Parliament and to local councils. A different system was also in use between 1999 and 2019 for United Kingdom elections to the European Parliament. Historically, only First Past the Post (FPTP) was used for all elections in Scotland, but this changed in 1999 both with the introduction of D'Hondt elections to the EU Parliament and the inception the same year of the devolved Scottish Parliament. Two of the devolved legislatures in the United Kingdom - the Scottish Parliament and the Senedd - use the Additional Members System (AMS). AMS has been used for every Scottish Parliament election since 1999, with the most recent being in 2021.
The Borda count is a family of positional voting rules which gives each candidate, for each ballot, a number of points corresponding to the number of candidates ranked lower. In the original variant, the lowest-ranked candidate gets 0 points, the next-lowest gets 1 point, etc., and the highest-ranked candidate gets n − 1 points, where n is the number of candidates. Once all votes have been counted, the option or candidate with the most points is the winner. The Borda count is intended to elect broadly acceptable options or candidates, rather than those preferred by a majority, and so is often described as a consensus-based voting system rather than a majoritarian one.
Instant-runoff voting (IRV) is an electoral system that uses ranked voting. Its purpose is to elect the majority choice in single-member districts in which there are more than two candidates and thus help ensure majority rule. It is a single-winner version of single transferable voting. Formerly the term "instant-runoff voting" was used for what many people now call contingent voting or supplementary vote.
An electoral system or voting system is used to elect candidates into various parts of government, and used for referendums in politics. Non-political elections may take place in business, non-profit organisations and informal organisations.
Hare-Clark is a type of single transferable vote electoral system of proportional representation used for elections in Tasmania and the Australian Capital Territory. The method for the distribution of preferences is similar to other voting systems in Australia, such as for the Australian Senate.
The mixed ballot transferable vote (MBTV) refers to a type of vote linkage-based mixed-member electoral system where a group of members are elected on local (lower) tier, for example in single-member districts (SMDs). Other members are elected on a compensatory national (upper) tier from a list and voters cast a single ballot where they may indicate their preferences separately.
The spare vote is a version of single transferable voting applied to the ranking of parties, first proposed for elections in Germany in 2013. This preferential party system is a ranked proportional representation electoral system applying to political parties instead of individual candidates. The spare vote refers to a secondary vote (preference) of the voter, which only comes into play if the first preference for the political party preferred by the voter, is below the electoral threshold. In Germany, there were draft laws for the spare vote system in Saarland, Schleswig-Holstein and Brandenburg federal states, but they were not implemented.
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