The two-round system, also called ballotage, top-two runoff, or two-round plurality, is a single winner voting method. It is sometimes called plurality-runoff, although this term can also be used for other, closely-related systems such as ranked-choice voting or the exhaustive ballot. It falls under the class of plurality-based voting rules, together with instant-runoff and first-past-the-post (FPP). In a two-round system, both rounds are held under choose-one voting, where the voter marks a single favorite candidate. The two candidates with the most votes in the first round proceed to a second round, where all other candidates are excluded.
The single transferable vote (STV), a type of proportional ranked choice voting, 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 alternative 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.
Voting refers to the process of choosing officials or policies by casting a ballot, a document used by people to formally express their preferences. Republics and representative democracies are governments where the population chooses representatives by voting.
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.
A group voting ticket (GVT) is a shortcut for voters in a preferential voting system, where a voter can indicate support for a list of candidates instead of marking preferences for individual candidates. For multi-member electoral divisions with single transferable voting, a group or party registers a GVT before an election with the electoral commission. When a voter selects a group or party above the line on a ballot paper, their vote is distributed according to the registered GVT for that group.
Historically, the single transferable vote (STV) electoral system has seen a series of relatively modest periods of usage and disusage throughout the world; however, today it is seeing increasing popularity and proposed implementation as a method of proportional representation and a goal of electoral reform. STV has been used in many different local, regional and national electoral systems, as well as in various other types of bodies, around the world.
Instant-runoff voting (IRV) is a ranked voting method used in single-winner elections. IRV is also known outside the US as the alternative vote (AV). Today it is in use at a national level to elect the Australian House of Representatives, the National Parliament of Papua New Guinea, the President of Ireland and President of India. In Australia it is also used for elections to the legislative assemblies of all states and territories except Tasmania and the Australian Capital Territory, and for the Tasmanian Legislative Council.
The contingent vote is an electoral system used to elect a single representative in which a candidate requires a majority of votes to win. It is a form of preferential voting. The voter ranks the candidates in order of preference, and when the votes are counted, the first preference votes only are counted. If no candidate has a majority of the votes cast, then all but the two leading candidates are eliminated and the votes received by the eliminated candidates are distributed among the two remaining candidates according to voters' preferences.
In voting, a ballot is considered spoilt, spoiled, void, null, informal, invalid or stray if a law declares or an election authority determines that it is invalid and thus not included in the vote count. This may occur accidentally or deliberately. The total number of spoilt votes in a United States election has been called the residual vote. In Australia, such votes are generally referred to as informal votes, and in Canada they are referred to as rejected votes.
Later-no-harm is a property of some ranked-choice voting systems, first described by Douglas Woodall. In later-no-harm systems, increasing the rating or rank of a candidate ranked below the winner of an election cannot cause a higher-ranked candidate to lose.
A Langer vote was a style of voting in the Australian electoral system designed to avoid the requirement to express preferences for all candidates without the vote being rejected as informal. The title is a tribute to Albert Langer, an Australian political activist, who advocated for the use of this style as a de facto method of optional preferential voting for making a valid vote for the voter's preferred candidates while the deliberate "error" avoided the vote being counted for one of the major political parties.
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.
Multiple transferable voting, sometimes called block preferential or block instant-runoff voting, is a winner-take-all system for electing several representatives from a multimember constituency. Unlike single transferable voting (STV), preferential block voting is not a method for obtaining proportional representation, and instead produces similar results to plurality block voting. Preferential block voting can be seen as a multiple-winner version of instant-runoff.
Instant-runoff voting (IRV), also known as ranked-choice voting (RCV), preferential voting (PV), or the alternative vote (AV), is a multi-round elimination rule where the loser of each round is determined by first-past-the-post voting. In academic contexts, the system is generally called instant-runoff voting to avoid conflating it with other methods of ranked voting in general.
An electoral or voting system is a set of rules used to determine the results of an election. Electoral systems are used in politics to elect governments, while non-political elections may take place in business, non-profit organisations and informal organisations. These rules govern all aspects of the voting process: when elections occur, who is allowed to vote, who can stand as a candidate, how ballots are marked and cast, how the ballots are counted, how votes translate into the election outcome, limits on campaign spending, and other factors that can affect the result. Political electoral systems are defined by constitutions and electoral laws, are typically conducted by election commissions, and can use multiple types of elections for different offices.
Ranked voting is any voting system that uses voters' rankings of candidates to choose a single winner or multiple winners. More formally, a ranked system is one that depends only on which of two candidates is preferred by a voter, and as such does not incorporate any information about intensity of preferences. Ranked voting systems vary dramatically in how preferences are tabulated and counted, which gives them very different properties.
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.
