Monday, 10 May 2010

2010 Election Results Under Different Voting Systems

Thanks to some number crunching from the Electoral Reform Society, we can now see what the election might have looked like under different voting systems.  I've taken their figures and plotted them below in a couple of different formats.  In each graph you can compare results as they actually are (under First-past-the-post) and results under AV (Alternative Vote), STV (Single Transferrable Vote - the Liberal Democrats preferred system) and under a fully proportional allocation (based on share of the national vote).  I don't think it takes much to realise that pretty much any of the alternatives is going to be fairer than FPTP, but there's still quiet a discrepancy between the different systems.


Aaron said...

The similarity between STV and PR is striking (though the size of the STV districts isn't given). Given that some degree of geographical representation is present, STV is pretty nice.

Though, I'd still keep an eye out for developing systems. There are working proportional variations of range and approval voting.

Spy Wednesday said...

Yes - the data from the Electoral Reform Society have a lot assumptions built into the model. Also, these numbers don't take into account the fact that people's voting behaviour as well as party campaigning behaviour changes with the electoral system. For example, in most countries with PR, people have a fair idea of what kind of coalitions they are likely to get beforehand (e.g., a centrist and centre-right grouping). and, as you say, there are other which may gain in popularity over time, especially if electronic voting/counting becomes more popular.