Electoral systems

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Electoral systems

  • A proportional electoral system tends to represent parties in-line with their electoral support, often portrayed as proportional representation.
    • This means that there is an equal, or close, and reliable relationship between the seats won by the parties and the votes that they gained.
    • For example, Weimar Germany had a proportional system.
  • A non-proportional electoral system tends to 'over-represent' larger parties and usually results in single-party majority government.
    • Larger parties win a high proportion of seats than the proportion of votes they gained.
    • Examples of countries with non-proportional systems include the UK and India.
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First-Past-The-Post - Features

First-Past-The-Post is the main non-proportional system used in the UK. It is used for elections to the House of Commons and in England and Wales for local government.


  • Constituency system
    • There are 650 parliamentary constituencies in the UK
  • Voters select a single candidate on the ballot paper
    • This reflects the principle of 'one person, one vote'
  • Constituencies are of roughly equal size.
    • This is ensured by the Electoral Commission and Boundary Commissions for Scotland and Northern Ireland.
  • Each constituency returns a single candidate
  • The winning candidate needs only to achieve a plurality of votes.
    • For example, if the votes were cast as follows:
      • Candidate A: 30,000 votes
      • Candidate B: 22,000 votes
      • Candidate C: 26,000 votes

Candidate A would win, despite polling only 30% of the vote.

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First-Past-The-Post - Advantages and Disadvantages


  • There is a strong link between the voters and the MP.
  • There is a high chance of there being single-party government.


  • It fails to establish a reliable link between the proportion of votes won by parties and the proportion of seats they gain.
  • Governments are usually formed without an absolute majority of the vote.
    • A party has not gained an absolute majority of votes in a UK general election since 1935.
  • There are systematic biases that depend on the size of a party and the distribution of support.
    • Larger parties tend to do better
    • Parties with geographically concentrated support tend to do better.
  • Votes are often wasted.
    • They are either cast for candidates without a chance of winning, they are in safe seats where the result is inevitable because one party is dominate, or they are cast for a candidate that has already won.
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Alternative Vote - Features

AV is used for Australia's lower chamber (the House of Representatives), Scottish local by-elections, Labour and Liberal leadership elections, and by-elections for hereditary peers.


  • Single-member constituencies.
  • Electors vote preferentially by ranking candidates in order.
  • Winning candidates must gain a minimum of 50% of all votes cast.
  • Votes are counted according to first preference. If no candidate reaches 50%, the bottom candidate drops out and their votes are redistributed according to subsequent preference. This continues until one candidate reachs 50%.
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Alternative Vote - Advantages and Disadvantages


  • AV ensures that fewer votes are 'wasted' than FPTP
  • As wining candidates must secure at least 50% support, a broader range of views and opinions incluence the outcome of the election.
    • Parties are drawn towards the centre ground.


  • The outcome of the election may be determined by the preferences of those who support small, possibly extremist parties.
  • Winning candidates may enjoy little first-preference support and only succeed with the help of redistributed supplementary votes, making them only the least unpopular candidate.
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Supplementary Vote - Features

SV has been used since 1999 for the election of the London Mayor. It is a shortened version of AV.


  • Single-member constituencies
  • Electors have two votes: a first preference and a supplementary vote.
  • Winning candidates in the election must gain a minimum of 50% of all votes cast.
  • Votes are counted according to first preference. If no candidate reaches 50%, the top two candidates remain in the election and the rest drop out, their vote being redistributed on the basis of their supplementary vote.
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Supplementary Vote - Advantages and Disadvantages


  • SV is simpler than AV, and so would be easier for voters to understand and use.
  • The focus on gaining second-preference votes encourages conciliatory campaigning and a tendency towards consensus.


  • Although fewer votes are wasted than in FPTP, SV does not ensure that the winning candidate has the support of at least 50% of the vote.
    • This is because a proportion of supplementary votes will be for candidates who have already dropped out.
  • The emphasis on making supplementary votes count may encourage voters to support only candidates from the main parties.
    • They may be discouraged from supporting their preferred second-preference candidate.
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Additional Member System - Features

AMS is sometimes called the mixed-member proportional system (MMP). It is used for elections to the Scottish Parliament, Welsh Assembly and the Greater London Assembly.


  • It is a 'mixed' system, made up of constituency and party-list elements.
  • A proportion of seats are filled by FPTP.
    • 56% in Scotland and London.
    • 66% in Wales
  • The remaining seats are filled using a 'close' party-list system.
  • Electors cast two votes: one for a candidate in a constituency election and the other for a party in a list election.
  • The party-list element in AMS is used to 'to up' constituency results.
    • This is done 'correctively' using the D'Hondt method, to achieve the most proportional overall outcome.
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Additional Member System - Advantages and Disadvan


  • The mixed character of this system balances the need for constituency representation against the need for electoral fairness.
  • Although the system is broadly proportional in terms of its outcomes, it keeps alive the possibility of single-party government.

  • It allows voters to make wider and more considered choices. For example, they can vote for different parties in the constituency and list elections.


  • The system creates confusion by having two classes of representative.

  • The retention of single-member constituencies reduces the likelihood of high levels of proportionality.
  • Constituency representation will be less effective than it is in FPTP, because of the larger size of constituencies and because a proportion of representatives will have no constituency duties.

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Single Transferable Vote - Features

STV is used for the Northern Ireland Assembly, in Northern Ireland and Scotland for local government and in Northern Ireland for European Parliament elections.


  • There are multi-member constituencies.
    • The Northern Ireland Assembly has 18 constituencies, each returning 6 members.
    • In local elections in Northern Ireland, there is a mixture of 5-, 6- and 7-member constituencies.
  • Electors vote preferentially.
  • Candidates are elected if they achieve a quote of votes calculated on the basis of the Droop formula.
  • Votes are counted, first, according to first preference. If any candidate achieves the quote, additional votes for them are counted according to subsequent preferences
  • If this process still leaves some seats unfilled, the candidate with the fewest votes drops out and their votes are redistributed according to subsequent preferences.
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Single Transferable Vote - Advantages and Disadvan


  • The system is capable of achieving highly proportional outcomes.
  • Competition amongst candidate from the same party means that they can be judged on their individual records and personal strengths.

  • The availability of several members means that constituents can choose who to take their grievances to


  • The degree of proportionality achieved in this system can vary, largely on the basis of the party system
  • Strong and stable single-party government is unlikely under STV.

  • Multi-member constituencies may be divisive because they encourage competition amongst members of the same party.

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Regional Party List - Features

The Regional Party List has been used for elections to the European Parliament since 1999. This brought the UK into line with the EU requirement that elections to the European Parliament should be proportional.


  • There are number of large multi-member constituencies.
  • For European Parliament elections, the UK is divided into 12 regions, each returning 3-10 members (72 in total).
  • Political parties compile lists of candidates to place before the electorate, in order of preference.
  • Electors vote for parties, not candidates.
  • The UK uses closed list elections.
  • Parties are allocated seats in direct proportion to the votes they gain in each regional constituency. They fill these seats from their party list.
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Regional Party List - Advantages and Disadvantages


  • It is the only potentially 'pure' system of proportional representations, and is therefore fair to all parties
  • The system tends to promote unity by encouraging electors to identify with a region rather than with a constituency.

  • The system makes it easier for women and minority candidates to be elected, provided they feature on the party list.


  • The existence of many small parties can lead to weak and unstable government.
  • The link between representatives and constituencies is significantly weakened and may be broken altogether

  • Parties become more powerful, as they decide where candidates are placed on the party list.

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