Swingometer

[ciphergoth]

Paul's two dimensional three-way swingometer

This is still a draft version of the swingometer, posted here to get some feedback on how to make it more comprehensible and more useful. A three-way election is a rather challenging thing to illustrate on a diagram, so I hope you'll forgive this being a little harder to follow than a normal two-way swingometer!

• Point the mouse at the "2005" on the image and you'll see the result for 2005; the share of the vote for each party, and the number of seats they hold. Strictly speaking it's a projection of 2005's result onto the 2010 constituencies.
• Move the mouse around the diagram and you'll see projections for what sort of parliament you might see as the vote share changes. These projections are based on the very simple "Uniform National Swing" model, which has many failings but AFAICT more sophisticated models don't do much better in practice.
• The colour of each hexagon illustrates who has the most seats; a majority is shown in a darker colour. Larger majorities get darker colours. Where two parties are exactly equal, we use an in-between colour. Just compare the colour of the hexagons with the share of seats indicated for each one to understand the colour scheme.
• The straight lines across the diagram indicate the lead in points of the party with the largest vote share. Where the three lines meet is the point where all three parties get the same number of votes.
• A fixed proportion of votes are shared between the three main parties It would be better if you could change how many votes go to other parties, but it's much harder to do.

I have plans for updating this diagram during election night, but they're even more complicated, so I'll come to that later. Please let me know what you think - does it make sense?

Comments

[drdoug.livejournal.com]

Algorithm no more than cutoff at -100.

Yay for absurdly simple algorithms that do a job well!

Will definitely comment on how unfairness of electoral system is illustrated in text.

My suggestion isn't quite accurate anyway, I realise.

the "click" idea. All ideas on what should be presented in the oodles of space that would allow very welcome.

For hung parliaments, it would be cool to show what majorities were possible - specifically, whether or not Lab/LibDem and/or Con/LibDem alliances would command a majority. Prob not much point to show a Lab/Con alliance commanding a majority, since it almost always would - maybe invert that one in the shiny yellow sliver and show 'Lab/Con alliance no majority' for the unlikely scenarios where this applies, to keep LibDem dreamers happy.

Many, many thanks!

You're welcome. Many, many thanks for making this! It's a cool tool and I shall use it repeatedly between now and May 8th.

[drdoug.livejournal.com]

... another quick thought on hung parliaments: in many scenarios where a party is close to a majority, the minor parties become hugely important. A Labour/SNP/Plaid/SDLP coalition is not entirely impossible, for instance, and nor is a Con/UUP/DUP(!) one. So if you're enumerating possible majority Government alliances, it'll be painfully obvious that restricting to the three biggest parties isn't covering all possibilities.

But OTOH, when you get down to that level of a handful of seats, you're well beyond the likely accuracy of a model like this, I reckon. Especially given that your model has to assume a fixed number of seats to 'others'. And there's all sorts of obscure fencepost type issues that generally don't matter but might suddenly do so in close-to-majority situation, like how many non-voting seats Sinn Fein occupy, the Speaker+Deputies, seats vacant due to death of candidates (there's at least one), etc. And of course the entirely non-zero probability that actual Independent MPs are highly significant.

So maybe just another point for the Notes.

[ciphergoth.livejournal.com]

Yes, I think trying to track the non-Big-3 parties is going to be out of reach; best that can be done is to say how many seats are held by "Other" parties, how far each Big 3 is from majority, and how far Lib-Con and Lib-Lab are.

One annoyance: if you've got 5 out of 9 seats, you have a "majority of one", but if you have 5 out of 10, you're "one short of a majority" - like BC/AD, there's no zero.

[ciphergoth.livejournal.com]

You're welcome. Many, many thanks for making this! It's a cool tool and I shall use it repeatedly between now and May 8th.

thanks! Will soon discuss plans for how to use it during election night - broadly, diagram will show makeup of Parliament assuming that *remaining* seats show a particular swing.