Tag Archive: yes2av

Apr 16 2011

The elephant in the room


In my last blog post I wrote about the AV referendum and party political self-interest. Before that I wrote about AV, preference and how parties hold their internal elections.

In this post I will just explain the chart at the top of the page.

It shows the number of parliamentary seats each of the three main national parties gained in the UK 2010 General Election under first-past-the-post (FPTP) – these are the blue bars. The red bars show the number of seats each party would expect to gain under Alternative Vote (AV), based on a mock election involving 13,000 people. Finally the yellow bars show the number of seats which would be obtained under a proportional system.

The proportional system, where the number of seats is proportional to the number of votes gained nationwide, is what I would call “fair”.

Labour and Tory parties both benefit significantly under the current FPTP system and proposed AV systems.

Apr 14 2011

Self-interest and electoral perversions

In this post I will argue that all of the political parties are arguing the case for AV in their own self-interest, this is very obviously what they are doing and admitting such will make a change.

I’d like to start with the electoral system as it stands today:

Two things are going on at an a general election: there are “local” elections in 650 constituencies which determine which individual represents each constituency in parliament and then there is the government formed as the result of this set of elections. Once elected to parliament MP’s represent their constituents interests but vote largely as whipped by their political party.

First past the post (FPTP) and Alternative Vote (AV) are both algorithms for determining local representation: they make no deliberate effort to make the output of a collection of constituencies proportional to the proportion of votes cast for a particular party across the country. The degree to which they give proportionality is dependent on the spatial distribution of voters for each party across the country and the locations in which electoral boundaries are drawn1. The current distribution of party support is not far off the point where it can give completely perverse results with the Liberal Democrats gaining the largest fraction of the popular vote and the fewest parliamentary seats and Labour gaining the smallest fraction of the popular vote and the largest number of parliamentary seats2.

The FPTP system acts to supress the formation of more than two political parties, this is known as Duverger’s law. You can see this in action in the UK, with the separation of the SDP from Labour in the early 1980’s, gaining a large fraction of the popular vote: approaching that of Labour, but nothing like the same number of seats3.

Best estimates for AV in a UK general election are that the Liberal Democrats will gain seats in a Westminster election and Labour and the Tories will lose some, it isn’t particularly clear who will lose most.

So moving on to the self-interest of parties:

The Liberal Democrats are in favour of AV because they will get more seats, this is OK because they will still have far fewer seats than their proportion of the vote should allow.

The Tories are against AV because they believe that they will lose seats to the Liberal Democrats for the same share of the vote, and that Labour-Liberal Democrat coalitions are more likely than Tory-Liberal Democrat coalitions. Wait! What?

Labour is split on AV, this is because some believe that Labour-Liberal Democrat coalitions are more likely than Tory-Liberal Democrat coalitions, and the Tories could be basically locked out of power for ever. Others in Labour, on the left of the party, believe that the Socialist utopia should be pure and that coalition is anathema and so oppose AV.

UKIP is in favour of AV because they believe that they will be first preference for a number of people who vote Tory tactically and second preference for a number of Tories. Their visibility will rise, even if it doesn’t lead to much increase in seats.

The Greens are in favour of AV because they believe they will pick up second preferences from Liberal Democrats and Labour.Their visibility will rise, even if it doesn’t lead to increased seats.

The BNP is against AV because it judges that it will not pick up second preferences from anyone. It decreases the likelihood of them gaining seats even if it increases the visibility of the party. The BNP is entirely visible already but for the wrong reasons.

Oddly those on either side of the debate are able to draw on arguments that match the self-interest of their parties. What is the non-aligned voter to make of this?


  1. Oxford is a nice example of this: across the two Oxford parliamentary seats (Oxford East and Oxford West and Abdingon) the number of votes for the three main parties are (LibDem: 41087, Tory: 33633, Lab: 27937. The two constituencies return a Labour and a Tory MP.
  2. Don’t believe me? Put Tory: 33.2%, Labour: 27.2%, LibDem: 27.7% Other: 11.9% into this BBC seat calculator. The actual result was Tory: 36.1%, Labour: 29.0%, LibDem: 23.0% Other: 11.9%
  3. The 1983 General Election. Vote share: Tory: 42.4% Labour: 27.6% SDP+Liberal Alliance: 25.4% Number of seats: Tory: 397 Labour: 209 SDP+Liberal Alliance: 23.
  4. Given 1-3, on what basis is it that we claim to live in a democracy?

Jan 10 2011

An electoral thought experiment

This morning I asked the good people of twitter:

Anybody else playing #fantasyAV? What would you vote under AV in the by-election in Oldham East & Saddleworth on Thursday?#yes2av

You can follow the responses to this question here. AV in this context is the “Alternative Vote” system, voters rank the candidates on the ballot paper using as many or as few numbers (1,2,3…) as they wish. My response to this question is:

  1. Liberal Democrat
  2. Tory
  3. Green

If you’re interested in my rationale then, as a committed, LibDem 1. is unsurprising! As a supporter of the Coalition then 2. also makes sense. 3. Is because I sort of like the Greens, although Caroline Lucas occasionally slips into “ConDem” mode she has at least made some attempt at providing policy alternatives.

The aim of such experiments is to reveal an underlying truth or at least think clearly about such truths. In this instance applying this to a concrete example helps make the proposal to move to the AV system real, it obliges you to think about what you’d actually do. For me the nice thing about AV is that my vote reflects my preferences for the outcome of the election, I’d like the LibDem candidate to win, I’d be happy if the Tory won and although I may not always agree with them I’m happy to show some support for the Green candidate. I can do all of this under AV without attempting to second guess what other people are going to vote in order to get my most preferred outcome given their votes, which is what I’m stuck with when the first-past-the-post system is used. In this particular by-election I imagine this issue is most acute for Tory voters, some fraction of them would prefer the LibDem candidate if their own candidate does not win. Under AV the answer is simple vote 1. Tory and 2. LibDem, under FPTP the answer to your voting dilemma is not clear.

Put another way AV is about getting more data from the voter. Under first-past-the-post I put one X in one box – very little data is transmitted from me, the voter. Under AV I get to put numbers, not just a single pre-literate mark, into more boxes, therefore more data is transmitted. There is a technical field of “Information Theory” which would tell you precisely how much more information is being transmitted. To use an example from my job, if we are trialling new products we will often ask consumer panels to rank variants rather than simply select their favourite because ranking gives us more information.

I won’t attempt to analyse the results of the responses I received in electoral terms. The “No to AV” campaigners steadfastly refused to accept they had anything other than a single preference. Others placed less mainstream choices such as the Pirate Party and the Greens before other parties. As someone pointed out: “Its already showing the liberating effect AV would have”. As a result of their rankings I learnt more about what they wanted the outcome of the election to be.

Personally I’d like to see a fully proportional system where the number of seats a party gains in parliament reflects the number of votes cast for that party. However, that system is not on offer. AV at least allows us to be honest in our voting, you give the highest rank to your favourite candidate.

What would you vote under AV in the by-election in Oldham East & Saddleworth on Thursday?