Single Transferable Vote (STV) and Supplementary Vote (SV)

Single Transferable Vote (STV)

STV is used in Northern Ireland Assembly elections to facilitate power-sharing.

Definition: STV is a form of proportional representation using ranked voting in multi-member constituencies.

Key features:

• 18 regions with 6 representatives each
• Voters rank candidates in order of preference
• Candidates must reach a 'Droop quota' to be elected

Vocabulary: The Droop quota is calculated as: (Total valid votes / (Number of seats + 1)) + 1

Effects on UK elections:

• Promotes multi-party systems and coalition governments
• Reduces the number of 'safe seats'
• Produces more proportional results

Advantages:

• Highly proportional results
• Offers greater voter choice
• Improves representation of diverse views

Disadvantages:

• More complex system
• Weakens the constituency link
• Can make single-party governments unlikely

Highlight: STV allows voters to choose between and within parties, offering a high degree of voter choice.

Supplementary Vote (SV)

SV is used to elect the Mayor of London every four years.

Definition: SV is a preferential voting system where voters express a first and second preference.

Key features:

• Two columns for first and second preferences
• If no majority after first preferences, top two candidates remain
• Second preferences are then redistributed

Effects on UK elections:

• Tends to maintain a two-party system
• Usually results in strong, single-party leadership
• Can lead to tactical voting

Advantages:

• Ensures a majority result
• Offers some voter choice
• Relatively simple to understand

Disadvantages:

• Can still lead to two-party dominance
• May produce 'false majorities'
• Many votes can be wasted

Example: In the 2016 London mayoral election, around 400,000 voters did not express a second preference, potentially reducing their influence on the final result.

This comprehensive guide to electoral systems in UK Politics provides essential information for students studying A-level Politics, particularly those following the Edexcel or AQA syllabi. Understanding these systems is crucial for analyzing voting behaviour and the complexities of UK elections.