Proportional representation

proportional representation systemproportionalproportional votingproportional systemPRproportional electoral systemproportional representativeproportionally representedproportional voting systemproportionally
Proportional representation (PR) characterizes electoral systems in which divisions in an electorate are reflected proportionately in the elected body.wikipedia
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Electoral system

multi-membervoting systemvoting systems
Proportional representation (PR) characterizes electoral systems in which divisions in an electorate are reflected proportionately in the elected body.
There are many variations in electoral systems, but the most common systems are first-past-the-post voting, the two-round (runoff) system, proportional representation and ranked voting.

Single transferable vote

proportionallysingle transferable ballotHare-Clark
The most widely used families of PR electoral systems are party-list PR, the single transferable vote (STV), and mixed-member proportional representation (MMP).
The single transferable vote (STV) is a proportional voting system designed to achieve proportional representation, or at least some minority representation, through ranked voting in multi-seat organizations or constituencies (voting districts).

Party-list proportional representation

party listparty-listlist
The most widely used families of PR electoral systems are party-list PR, the single transferable vote (STV), and mixed-member proportional representation (MMP).
Party-list proportional representation systems are a family of voting systems emphasizing proportional representation in elections in which multiple candidates are elected (e.g., elections to parliament) through allocations to an electoral list.

Mixed electoral system

mixed systems
Mixed member proportional representation (MMP), also called the additional member system (AMS), is a two-tier mixed electoral system combining a non-proportional plurality/majoritarian election and a compensatory regional or national party list PR election.
A mixed electoral system is an electoral system that combines a plurality/majoritarian voting system with an element of proportional representation (PR).

Open list

preference votesopenpreferential votes
Lists can be "closed" or "open"; open lists allow voters to indicate individual candidate preferences and vote for independent candidates.
The members of the National Council are elected by open list proportional representation in nine multi-member constituencies based on the states (with varying in size from 7 to 36 seats) and 39 sub-constituencies.

Additional member system

additional membersadditional memberadditional-member
Mixed member proportional representation (MMP), also called the additional member system (AMS), is a two-tier mixed electoral system combining a non-proportional plurality/majoritarian election and a compensatory regional or national party list PR election.
The additional member system (AMS), also known as mixed-member proportional representation (MMP) outside the United Kingdom, is a mixed electoral system with one tier of single-member district representatives, and another tier of ‘additional members’ elected to make the overall election results more proportional.

Plurality voting

majority votefirst past the postsingle-member
PR tries to resolve the unfairness of majoritarian and plurality voting systems where the largest parties receive an "unfair" "seat bonus" and smaller parties are disadvantaged and have difficulty winning any representation at all (Duverger's law).
This combination is also variously referred to as winner-takes-all to contrast it with proportional representation systems.

Wasted vote

wastedwastewasted" votes
During the count, as candidates are elected or eliminated, surplus or discarded votes that would otherwise be wasted are transferred to other candidates according to the preferences. Since most votes count, there are fewer "wasted votes", so voters, aware that their vote can make a difference, are more likely to make the effort to vote, and less likely to vote tactically.
In proportional representation representatives are elected at least in rough proportion to voter preferences, resulting in generally fewer wasted votes than in plurality voting.

Duverger's law

tendencytwo party system which first past the post rewards
PR tries to resolve the unfairness of majoritarian and plurality voting systems where the largest parties receive an "unfair" "seat bonus" and smaller parties are disadvantaged and have difficulty winning any representation at all (Duverger's law).
In political science, Duverger's law holds that plurality-rule elections (such as first past the post) structured within single-member districts tend to favor a two-party system, whereas "the double ballot majority system and proportional representation tend to favor multipartism".

Tactical voting

strategic votingvote tacticallystrategically
Since most votes count, there are fewer "wasted votes", so voters, aware that their vote can make a difference, are more likely to make the effort to vote, and less likely to vote tactically.
For multi-winner elections, Evaluative Proportional Representation (EPR) in Section 5.5.5 in Proportional Representation further reduces tactical voting by assuring each citizen that their honest vote will proportionately increase the voting power of the elected candidate in the legislature who receives either their highest grade, remaining highest grade, or proxy vote.

Israel

State of IsraelIsraeliISR
The example of Israel is often quoted, but these problems can be limited, as in the modern German Bundestag, by the introduction of higher threshold limits for a party to gain parliamentary representation.
The country has a liberal democracy (one of only two in the Middle East and North Africa region, the other being Tunisia), with a parliamentary system, proportional representation, and universal suffrage.

Electoral threshold

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Note intermediate PR systems with a high electoral threshold, or other features that reduce proportionality, are not necessarily much fairer: in the 2002 Turkish general election, using an open list system with a 10% threshold, 46% of votes were wasted.
In Australia, which uses a single transferable vote proportional representation system, they avoided the need for a formal electoral threshold by establishing smaller electorates with each multi-member electorate returning fewer members of a Parliament and as such requiring a higher quota percentage in order to be elected.

Republic of Ireland

IrelandIrishRepublic
STV, despite long being advocated by political scientists, is used in only two: Ireland, since independence in 1922, and Malta, since 1921.
The Dáil has 158 members (Teachtaí Dála) elected to represent multi-seat constituencies under the system of proportional representation and by means of the single transferable vote.

Safe seat

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However some experts argue that transitioning from plurality to PR only increases voter turnout in geographical areas associated with safe seats under the plurality system; turnout may decrease in areas formerly associated with swing seats.
This is often regarded as undemocratic, and is a major argument in favour of various multi-member proportional representation election methods.

Semi-proportional representation

semi-proportionalsemi-proportional outcomessemi-proportional system
Under parallel voting, a semi-proportional system, there is no compensation for the effects that such gerrymandering might have.
Semi-proportional voting systems can be regarded as compromises between forms of proportional representation such as party-list PR, and plurality/majoritarian systems such as first-past-the-post voting.

UK Independence Party

UKIPUnited Kingdom Independence PartyLeader of the UK Independence Party
Similarly, in the 2015 UK General Election, the Scottish National Party gained 56 seats, all in Scotland, with a 4.7% share of the national vote while the UK Independence Party, with 12.6%, gained only a single seat.
Holmes took over as party leader, and in the 1999 European Parliament elections—the first UK election for the European Parliament to use proportional representation—UKIP received 6.5% of the vote and three seats, in South East England (Farage), South West England (Holmes), and the East of England (Jeffrey Titford).

Gallagher index

Gallagher index of dis-proportionalitydisproportionalityGallagher index of disproportionality
A number of such indexes has been proposed, including the Loosemore–Hanby index, the Gallagher Index, and the Sainte-Laguë Index.
The Gallagher index "measures an electoral system’s relative disproportionality between votes received and seats allotted in a legislature."

Electoral district

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The most prevalent forms of proportional representation all require the use of multiple-member voting districts (also called super-districts), as it is not possible to fill a single seat in a proportional manner.
Members might be chosen by a first-past-the-post system or a proportional representative system, or another voting method entirely.

Loosemore–Hanby index

A number of such indexes has been proposed, including the Loosemore–Hanby index, the Gallagher Index, and the Sainte-Laguë Index.
The Loosemore–Hanby index measures disproportionality of electoral systems.

Tony Blair

BlairTonyPrime Minister Tony Blair
In the 2005 UK election, for example, the Labour Party under Tony Blair won a comfortable parliamentary majority with the votes of only 21.6% of the total electorate.
Ashdown also claimed that Blair was a supporter of proportional representation (PR).

Electoral list

list of candidateslistlists
Party list proportional representation is an electoral system in which seats are first allocated to parties based on vote share, and then assigned to party-affiliated candidates on the parties' electoral lists.
An electoral list is a grouping of candidates for election, usually in proportional electoral systems, but also in some plurality electoral systems.

Parallel voting

Mixed member majoritarianSupplementary Memberparallel system
Under parallel voting, a semi-proportional system, there is no compensation for the effects that such gerrymandering might have.
It is also argued that SM does not lead to the degree of fragmentation found in party systems under pure forms of proportional representation.

2011 Irish general election

2011 general election2011February 2011
The same effect may have contributed to the collapse of Fianna Fáil in the 2011 Irish general election.
Ireland uses proportional representation with a single transferable vote, also known as PR–STV.

John Stuart Mill

MillJ.S. MillJ. S. Mill
The case for proportional representation was made by John Stuart Mill in his 1861 essay Considerations on Representative Government:
In Considerations on Representative Government, Mill called for various reforms of Parliament and voting, especially proportional representation, the single transferable vote, and the extension of suffrage.

Politics of the Republic of Ireland

IrelandIrish politicsIrish
After the introduction of STV in Ireland in 1921 district magnitudes slowly diminished as more and more three-member constituencies were defined, benefiting the dominant Fianna Fáil, until 1979 when an independent boundary commission was established reversing the trend.
Members of the Dáil are directly elected at least once in every five years under the single transferable vote form of proportional representation from multi-seat constituencies.