Monday, 7 November 2016

There's lies, damned lies and political pie charts

There's been a graphic doing the rounds which, according to the Independent 'Remain supporters are using to invalidate the decision to leave the EU.' It looks like this:

The yellow segment is the those who voted to leave. Look how small it is compared to the whole set of public who could, in principle have voted. (Blue is remain and the two grey bits are people who didn't register, and registered but didn't vote.) This is being taken as disproving the idea that Brexit is 'the will of the people' as worked up Brexiteers tend to blather, because it appears to be a minority decision.

Unfortunately, those who use this chart simply don't understand the statistics that arise from a voting system like ours. You could never definitely say what the will of the people is for sure unless you force everyone to vote. Look at this chart below. Here the grey section is the equivalent of the yellow section above - it's the people who voted for the actual outcome. A far smaller slice.


Terrible, isn't it? Clearly not democratic. Yet the grey section is the percentage of people voting for the government in the 2015 election.

The fact is that unless you do make it a legal requirement to vote, you have to assume that those who don't vote don't mind the outcome and can't be counted. It's the only possible sensible thing to do - and because of that, the way these pie charts are being used is manipulative and wrong. I don't mind you arguing for or against Brexit. Each has powerful arguments. But I do mind if you are going to misuse statistics.

5 comments:

  1. You are, of course correct; we do not know the opinion of those who didn't vote or those who didn't register to vote. If they had an opinion at all. And, there is a strong argument that if you can't be bothered to vote , and your not being registered to vote is due to your not being bothered to register (as opposed to a change of address or some other administrative glitch), then you should be happy with the result of an election or referendum no matter which way it goes.

    But, and this is a criticism of the stupid way in which the referendum was set up, for such an important change, there should have been some requirements such as

    (i) the result would be invalid if less than 50% of the electorate voted

    and

    (ii) to change the current situation should require a e.g. 60% (or more?) vote to leave, not a simple majority of those who voted.

    Most countries, if they hold referenda, require larger than 50% votes to make such a fundamental change. And/or they require e.g. 30 of the 50 states in the case of the US to vote in favour to make an amendment to the constitution.

    Given the magnitude of this decision (and I don't think anyone, Remain or Brexit, would argue that it was not a momentous decision), it should not have been "just 50.1% of those who can be bothered to vote".

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  2. I agree that the percentage argument doesn't hold up. However I do think there are legitimate reasons for considering the referendum invalid and certainly not 'the will of the people'. The margin was relatively close and the main reason Leave won, was that they had a much better and more manipulative marketing campaign - the Stronger In campaign was just feeble. It's as though they were trying target a very narrow win, maybe to get leverage with the EU. As many have pointed out the margin should have been higher than 50% for such a wide-ranging change, anyway. Another thing that bugs me is that there is no general agreement on what we were voting for. Stephen Phillips, the MP who has just resigned, wrote in the Guardian on 12th October that he thought we would remain in the single market (as per the Conservative manifesto) if Leave won, whereas in the same week Jacob Rees-Mogg stated firmly on the Daily Politics that 'everyone who voted Leave knew that it meant leaving the single market'. So the 'will of the people' depends on which people you talk to, and is a complete nonsense.

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  3. A very interesting post and 2 (so far) comments uncharacteristically considered and rational compared to many I've seen on the EU debate. I speak as someone who voted In and who is very concerned about the vitriolic anger in the country on what was a 3.8% majority. That is a majority, obviously, but it can hardly be justified as the "will of the people". That should be enough without then going on to distort the data in a blatant and, frankly, ridiculous way. I have heard arguments made along similar lines (and opposed a few) but I have not seen the pie chart before. Do you have a source?

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  4. Thanks for interesting comments. I still think that the ‘didn’t vote’ wedges arguably should be considered for the winning side, as they apparently don’t mind. It’s an interesting one. As I pointed out to Rhodri on Facebook, if his restrictions had been in place we wouldn’t have a Welsh Assembly either...

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  5. "The fact is that unless you do make it a legal requirement to vote, you have to assume that those who don't vote don't mind the outcome and can't be counted. It's the only possible sensible thing to do." this is nonsense. if you don't like either outcome you are given to choose from, it makes total sense not to vote for either. it helps deny the winner any claim of having a mandate. as they say "don't vote. it only encourages them" and "the lesser of two evils is evil."

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