20 April 2011

AV's Main Advantage - Eliminating The Spoiler Effect.

Brian Barder uses an argument that AV is not worth having because there are not many seats that have 'the spoiler effect'.

The spoiler effect is where our current system - first-past-the-post, delivers victory to a candidate disliked by a majority just because the majority of voters are split between two or more candidates they liked more. Eliminating the spoiler effect is THE main advantage of AV.

Brian reckons spoiler seats are rare and he also claims that voting anything other than Labour or Tory is an ideological cop-out. Brian is a true believer in two-party politics and first-past-the-post is perfect for that, it punishes those who want a wider choice.

Thankfully, Brian's opinion is in a minority, only 18% of voters think ‘One political party comes close to reflecting my views and values; I am strongly opposed to all of the others.’

Yet this statement is the raison d'etre of first-past-the-post, the reality is that most people like more than one party fairly equally and AV would do more to reflect this. 82% of voters want change, what the YES vote has so far failed to do is persuade people that AV is a change worth having.

But is there any truth in Brian's other claim about the spoiler effect being rare? On first inspection there is. About of third of seats in a UK general election are won by a candidate with more than 50% of the vote and about another third are won where a candidate has over 45%.

By definition a candidate that wins over 50% cannot be in a spoiler seat, and those with over 45% are unlikely to be spoilers. So already we are only talking about a third of seats. Therefore in a technical sense Brian does have a point but of course the seats that count are the ones that change hands not the overall total.

AV might only affect a small percentage of the total seats, but this could be a massive percentage of the seats that actually decide an election. Of the final third of seats, less than half change hands in a typical UK general election. Under AV this will increase but estimates suggest not by that much, but of course nobody knows for sure, we can however look to Australia for guidance on what is really likely to happen.

Australia has few seats in its federal election where the candidate who came second or third went on to win and these are precisely the sort of seats we think might demonstrate how the spoiler effect is undone. In fact only 3 MPs won this way out of 150 in 2010. But this masks what is really going on. For a start only 20 seats changed hands anyway, so 3 is 15% of these seats that matter - critical to the overall result - which was famously close. (We have to remember that Australia only has 150 seats (which makes proportionality more difficult) and 20 seats changing hands are 13.3% of the total. In the UK there are 650 seats and the average for a non-major boundary change election is less than 5% of seats changing hands).

But more interesting than this is which way the preferences are going and how the vote is split. The left of centre vote is far more split than the right, so all of the 3 seats where the candidate won on 2nd or more preferences, are for centre left candidates, 1 Labour, 1 Green and 1 Independent. But even where the centre-left candidate still lost, he made up ground on the transfers, making the seat far more marginal than it would have been. The main centre-right parties National and Liberal rarely stand against each other but when they do, they too can benefit from avoiding the spoiler effect under AV. But this was an election where the pendulum swung the Lib/Nats way and this is why there are so few seats that changed hands on transferred preferences.

To find out how important the elimination of the spoiler effect is, we have to go back to Australia's general election of 2007 when the electoral pendulum was swinging towards Labour and they were gaining seats. Here, of the 27 seats that changed hands, 10 seats, or nearly 40% were decided on transfers, 9 of the 10 were in Labour's favour. The left vote is nearly always more split (largely because of the success of the Greens), so transfers always benefit the left the most. This is why anybody on the left should vote YES to AV.

So, although the number of seats that AV affects can be small in terms of total number of seats, it's impact can be massive because it is a large percentage of the seats that matter (and also allows people to vote freely for who they want and makes many more seats marginals). Vote YES to AV on May 5th.

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