Plurality voting refers to electoral systems in which the candidates in an electoral district who poll more than any other are elected.
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. Under other election systems, a bare plurality or a scant majority are all that are used to elect candidates. PR systems provide balanced representation to different factions, reflecting how votes are cast.
Party-list proportional representation (list-PR) is a system of proportional representation based on preregistered political parties, with each party being allocated a certain number of seats roughly proportional to their share of the vote.
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.
Single non-transferable vote or SNTV is an electoral system used to elect multiple winners. It is a semi-proportional variant of first-past-the-post voting, applied to multi-member districts where each voter casts just one vote. SNTV generally makes it unlikely that a single party will take all seats in a city, as generally happens with winner-take-all systems. SNTV can be considered a variant of dot voting where each voter has only one point to assign.
The additional-member system (AMS) is a two-vote seat-linkage-based mixed electoral system used in the United Kingdom in which most representatives are elected in single-member districts (SMDs), and a fixed number of other "additional members" are elected from a closed list to make the seat distribution in the chamber more proportional to the votes cast for party lists. It is distinct from using parallel voting for the list seats in that the "additional member" seats are awarded to parties taking into account seats won in SMDs – these are ignored under parallel voting.
Mixed-member proportional representation is a type of representation provided by some mixed electoral systems which combine local winner-take-all elections with a compensatory tier with party lists, in a way that produces proportional representation overall. Like proportional representation, MMP is not a single system, but a principle and goal of several similar systems. Some systems designed to achieve proportionality are still called mixed-member proportional, even if they generally fall short of full proportionality. In this case, they provide semi-proportional representation.
Block or bloc voting refers to a class of electoral systems where multiple candidates are elected simultaneously. They do not guarantee minority representation and allow a group of voters to ensure that only their preferred candidates are elected. In these systems, a voter can select as many candidates as there are open seats. That is, the voter has as many votes to cast as the number of seats to fill. The block voting systems are among various election systems available for use in multi-member districts where the voting system allows for the selection of multiple winners at once.
In political science, parallel voting or superposition refers to the use of two or more electoral systems to elect different members of a legislature. More precisely, an electoral system is a superposition if it is a mixture of at least two tiers, which do not interact with each other in any way; one part of a legislature is elected using one method, while another part is elected using a different method, with all voters participating in both. Thus, the final results can be found by calculating the results for each system separately based on the votes alone, then adding them together. A system is called fusion or majority bonus, another independent mixture of two system but without two tiers. Superposition is also not the same as "coexistence", which when different districts in the same election use different systems. Superposition, fusion and coexistence are distinct from dependent mixed electoral systems like compensatory (corrective) and conditional systems.
An electoraldistrict, sometimes called a constituency, riding, or ward, is a subdivision of a larger state created to provide its population with representation in the larger state's legislature. That body, or the state's constitution or a body established for that purpose, determines each district's boundaries and whether each will be represented by a single member or multiple members. Generally, only voters (constituents) who reside within the district are permitted to vote in an election held there. District representatives may be elected by a first-past-the-post system, a proportional representative system, or another voting method. They may be selected by a direct election under universal suffrage, an indirect election, or another form of suffrage.
Elections in Chile are held nationwide, including the presidency, parliament, regional offices, and municipal positions. Chilean citizens and foreign residents with legal residency of at least five years, who are 18 years or older on election day, are eligible to vote. Previously, voting was voluntary, but since 2023, it has become compulsory.
Multi-member constituencies existed in the Parliament of the United Kingdom and its predecessor bodies in the component parts of the United Kingdom from the earliest era of elected representation until they were abolished by the Representation of the People Act 1948. Since the 1950 general election, all members of the House of Commons have been elected from single-member constituencies.
Plurality block voting, a type of block voting method for multi-winner elections. Each voter may cast as many votes as the number of seats to be filled. The candidates with the most votes are elected. The usual result when the candidates divide into parties is that the most-popular party in the district sees its full slate of candidates elected, even if the party does not not have support of majority of the voters.
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.
A winner-take-all electoral system is one where a voting bloc can win all seats in a legislature or electoral district, denying representation to any political minorities. Such systems are used in many major democracies. Such systems are sometimes called "majoritarian representation", though this term is a misnomer, as most such systems do not always elect majority preferred candidates and do not always produce winners who received majority of votes cast in the district, and they allow parties to take a majority of seats in the chamber with just a minority of the vote.
The dual-member mixed proportional (DMP) voting method is a mixed electoral system using a localized list rule to elect two representatives in each district. It is similar to other forms of mixed-member proportional representation but differs in that all representatives are elected locally in small districts, rather than requiring separate list seats to be filled in large regional or nationwide districts. In the first step, one seat in each district is awarded to the candidate with the most votes, as with first-past-the-post voting rules. In the second step, underrepresented parties are assigned secondary seats in the districts in which they won the most votes, which creates an overall proportional result.
A mixed electoral system is one that uses different electoral systems to elect different seats in a legislature. Most often, this involves a winner-take-all component combined with a proportional component. The results of the combination may be mixed-member proportional (MMP), where the overall results of the elections are proportional, or mixed-member majoritarian, in which case the overall results are semi-proportional, retaining disproportionalities from the majoritarian component. Systems that use multiple types of combinations are sometimes called supermixed.
A mixed single vote (MSV) is a type of ballot in mixed-member electoral systems, where voters cast a single vote in an election, which used both for electing a local candidate and as a vote for a party affiliated with that candidate according to the rules of the electoral system. Unlike most mixed proportional and mixed majoritarian systems where voters cast two votes, split-ticket voting is not possible under MSV. This significantly reduces the possibility of manipulating compensatory mixed systems, at the price of reducing voter choice. An alternative based on the mixed single vote that still allows for indicating different preferences on different levels is the mixed ballot, which functions as a preferential (mixed) single vote.
Mixed-member majoritarian representation (MMM) is type of a mixed electoral system combining winner-take-all and proportional methods, where the disproportional results of the winner-take-all part are dominant over the proportional component. Mixed member majoritarian systems are therefore categorized under semi-proportional representation, and are usually contrasted with mixed-member proportional representation (MMP) which aims to provide proportional representation compensation ("top-up") seats.
Compensation or correction is an optional mechanism of electoral systems, which corrects the results of one part of the system based on some criterion to achieve a certain result, usually to make it more proportional. There are in general two forms of compensation: vote linkage and seat linkage.
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