3.1.2

AMS & SV

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Additional Member System (AMS)

The Additional Member System (AMS) is used for Welsh Assembly, Scottish Parliament and the Greater London Assembly elections.

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Additional Member System

  • AMS is an electoral system where voters have two votes: one vote for their constituency representative using FPTP and a second vote for a ‘party list’ in order to elect an ‘additional’ representative.
  • The party list uses multi-member regional constituencies and a party’s list of candidates is published before the election.
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Additional members

  • After the FPTP style voting for constituency representatives has been counted, additional members are added proportionally based on the proportion of voting support for each party so that parliament more closely matches how the country voted.
  • Additional members are added to regional constituencies to match how the constituencies voted, and may increase a party’s representation in the area if they had a lot of support but couldn’t win against safe seats.
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Scottish Parliament

  • In Scottish Parliament elections, 73 members are elected by FPTP and whilst 56 seats are filled by using list members.
  • The 56 additional members are allocated to 8 regional seats, and there are 7 additional members per region.
  • The number of additional members each party gets depends on the proportion of votes they receive in an election.
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Advantages: choice

  • AMS gives voters more choice because they can use one vote for an MP they support and another to support a party of their choosing.
    • Voters can vote for a ‘split ticket’ where they support an MP from one party and use their party list vote to support a different party.
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Disadvantages

  • Smaller parties are less well represented under AMS than in an entirely proportional system because the party list system can advantage the largest parties.
    • In Wales, there are a small number of top-up seats, which favours the Labour Party.
  • Party list candidates have less legitimacy than members elected by the FPTP vote because they aren’t directly elected with a personal mandate from voters.
  • AMS lacks democratic transparency because the party decides who is on the party list and ranks the order of candidates.

Supplementary Vote (SV)

The Supplementary Vote (SV) was used for London Mayoral elections and to elect Police and Crime Commissioners in England and Wales.

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Supplementary Vote

  • In the SV system, a voter has a first and second preference vote with a candidate elected for winning more than 50% of the first preference votes.
  • If no candidates win over 50% of the vote, then all candidates are eliminated except the top two who will have second preference votes allocated to decide the winner.
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Advantages

  • SV is a simple voting system because voters only need to select a first and second preference through marking two Xs rather than writing multiple numbers.
  • SV stops candidates winning through having a small level of support and encourages more positive campaigning as candidates need the second preference votes of other parties.
    • SV ensures large support for the winning candidate such as with Sadiq Khan winning 56.8% of the total vote in the 2016 London Mayor election.
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Disadvantages 1

  • Votes can be wasted because voters only choose two candidates meaning that many votes can be excluded from the final count if their top two candidates are eliminated.
    • In the 2012 London Mayor election, 15% of votes were wasted in round one and over 7% of votes in round two.

Disadvantages 2

  • SV is not proportional to the wishes of a region - only one candidate is elected, rather than multiple proportionally reflecting the wishes of the voters.
  • The winning candidate does not require an absolute majority (over 50%) of votes and so can be elected with minority support - they just need the most votes in total after the second round.

Jump to other topics

1Democracy & Participation

2Political Parties

3Electoral Systems

4Voting Behaviour & the Media

5Conservatism

6Liberalism

7Socialism

8The UK Constitution

9The UK Parliament

10The Prime Minister & the Executive

11Relationships Between Government Branches

12US Constitution & Federalism

13US Congress

14US Presidency

15US Supreme Court & Civil Rights

16US Democracy & Participation

17Comparing Democracies

18Feminism

19Nationalism

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