Having been keeping an eye on the election coverage, I realised that there's a lot of talk of swing but that I didn't actually know how it was defined.
So I went on a fact-finding mission.
Wikipedia has a nice straightforward article which answered most of my questions. However I was interested to see that there was actually a paper written for the House of Commons Library that describes it too.
Anyway, it all got me thinking about how swing as defined is very much restricted to two parties and doesn't really make a lot of sense when there are three parties challenging for a particular seat. So, I'm in the process of fiddling about and trying to come up with something myself that makes sense for that case.
Then I'll do some Googling to see what's been done before.
[Image credit: Sarah G]