Tag Archives: maths

Beermat Maths

I’ve been doing some beermat maths regarding the recent UK election. It started with my spreadsheet where I mapped out how many seats each party should have won based on proportional representation compared with how many they got (Tories, Labour, and SNP got too many; Greens and UKIP got too little), and has progressed a little more into a armchair political theorist discussion on the effects of proportional representation on the electorate.

My hypothesis is that proportional representation (PR) would not only give a fairer distribution of parliamentary seats, but also radically change the makeup of those seats. Most of this comes from the aforementioned beermat maths.

The first thing to be aware of is that 46.4 million Britons are currently eligible to vote (only about 30.6 million voted), and that there are 650 parliamentary seats at present. That means that in order to get a seat in a PR system, you should only need 71,424 votes. That number is the magic one that makes all of the rest of this slide into place.

Currently, the candidate with the highest proportion of votes in each constituency gets the seat – regardless of how many votes they actually got. This means that there are many seats where the sitting candidate has less than 40% of the votes from their district – but they’re supposed to represent 100% of the people in it. Somehow, that seems unlikely to me. It is my belief that because of this, many voters vote for parties whose policies they do not support fully out of a “better than the alternatives” mindset. So not only are people not getting the people they want in parliament, they’re settling for who they think can win it and do alright by them.

While proponents of the Green Party[1] are decrying the fact that they only got 1 seat (0.15% of the seats) with 3.8% of the votes, others are supporting the current system for ensuring that UKIP only got one seat despite having 12.6% of the vote. The popular belief here is that PR would be good for both parties, but Britain might suffer under more UKIP representation. I believe that the numbers from the current election do not reflect in any way the numbers we would get under a PR system.

It is my belief that a PR system would open the door to a political system that actually invites people to have the representation they want. If your vote is a national vote rather than a local vote, then it doesn’t matter if you’re the only person in a 100 mile radius to vote for CISTA[2] because as long as there are 71,423 other people across the country that want CISTA to have a representative. Being able to vote for a political platform you believe in without having to settle for a party that might win has to mean that people will vote for the parties they actually believe in.

It is my belief that bringing in PR will massively boost the less mainstream parties, and encourage people to vote for groups that get them what they want without going to the extremes of UKIP. I believe that a PR system will actually reduce the number of UKIP votes, not increase them. I also believe that PR will increase voter turnout as every vote will matter – your vote won’t be washed away by 40% of your constituency voting for a bigger party.

It is my belief that all of the smaller parties will benefit from PR and that the larger mainstream parties will suffer and it is because of this that no right-thinking Conservative will allow anything like a bill changing the vote to a PR system to pass before the next election no matter how much the other parties rally behind it. We may get a concession towards a better voting system in the future, but I can’t think that PR would do anything but hurt the Conservative party, and they’re unlikely to support a system that removes them from power in the next election.

The maths on this election is rather fascinating. 36.9% of the voters voted for the Conservatives but they won 50.9% of the seats. 66.1% of the electorate showed up to vote, which means that 24.4% of the electorate determined 50.9% of the seats. Given how the election maths actually works, any Conservative votes in areas that don’t have a Tory seat should be discounted as they didn’t contribute towards the won seats, and that actually makes it worse. I don’t have those figures, but that means that less than 24% of the eligible voters determined over half of the seats – when those are the numbers you’re looking at, can you really support First Past The Post as a valid method of determining who gets to sit in parliament?


All numbers referenced in this post were drawn from the BBC election results webpage and the derived interpretation is my own.

There are already various efforts to change the electoral system, including this Green Party campaign and the Make Seats Match Votes campaign.

Featured graphic from Morag Hannah, a Green Party candidate standing in the  Holyrood 2016 election. She was corrected on Twitter as it is in fact an Euler diagram but I didn’t feel the need to upload the corrected graphic.


UPDATE: This campaign for fairer representation by a teenager too young to vote has now broached 200,000 signatures and momentum is still gaining. There’s a part of the petition that I like that expresses my feelings quite succinctly:

“I don’t want to vote for a party I disagree with to keep out a party that I disagree with even more. I want to vote for a party that I believe in.”


 

UPDATE: I have been pointed at Martyn Eggleton’s D’Hondt analysis of the election[3] which splits votes by region and works out proportional representation on that basis. It’s interesting to look at, and the figures are interesting. The Conservatives and Labour have more seats under than my nationally based figures suggest, and UKIP and Green both lose seats comparatively. Local parties like Plaid Cymru, Sinn Fein, and the Democratic Unionist Party come out ahead in there areas rather than losing seats.

This analysis doesn’t hugely appeal to me as much as my own does purely from the bias that my vote (for the Green Party) wouldn’t matter as only 39,025 people in Scotland voted for the Green Party this election, and that isn’t enough to score a seat in Scotland.[4] However, I still think that under this system you’d see a better representation of what people wanted from their government and that people would be more likely to vote for the party they believed in.

 

Footnotes   [ + ]

1. Full disclosure: I am not a member of any of the Green Parties, but I support their political viewpoints and voted for the Scottish Greens
2. The Cannabis Is Safer Than Alcohol Party
3. Credit to Phil Hyde for the link.
4. Interestingly, UKIP got 47,078 votes in Scotland which is more than I thought they would but not actually that much more than the Green Party.