A change in the UK electoral system to the alternative vote would mean that in Belfast South, voter power would increase by 6%.

The power of voters in this constituency is based on the probability of the seat changing hands and its size.

If we changed the electoral system to AV the Voter Power of this seat would increase from 1.072 to 1.140.

THE EFFECTS OF AV

The Voter Power score under first past the post and alternative vote in Belfast South.

FPtP

1.072

AV

1.140

Constituency marginality

Very marginal

(no change from FPtP to AV)

How does Belfast South compare?

Analysis from nef suggests that switching from First Past the Post to the Alternative Vote would have the following effects across the UK:

  • An increase in the average power of UK voters from 0.285 of a vote to 0.352 of a vote (where a score of 1 is a fair vote).
  • An increase in the number of very marginal seats from 81 to 125, an increase of 44 seats.
  • A reduction in the number of very-safe seats from 331 to 271 a reduction of 60 seats.
  • A small reduction of inequality in the power of votes with the most powerful fifth of electors going from having 21 times the power of the least powerful fifth down to 18 times.

UK constituency marginality under FPtP and AV

Percentage of seats by category of marginality.

You decide. Thurs, 5 May 2011

On 5th May 2011 Britain will hold a referendum to decide whether to switch to the alternative vote for elections to the House of Commons. This is your chance to have a say on the future of our constitution.

More information on the referendum and how to vote can be found at About My Vote, from the Electoral Commission.

Voter Power Index report from nef

The Voter Power Index is based on research by nef (the new economics foundation)

If you would like to know more about how the Voter Power Index is calculated, download the full report (PDF).

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