Over on Facebook, Jason made a very perceptive comment about my last post. He suggested that my section about FPTP being horrible disproportional was unfair, because the disproportionality between votes and seats is a function of having single-member constituencies, rather than the voting system.

But is it, really? Of course, we can test this.

Britain uses FPTP, and, if you remember, its vote/seat disproportionality looks like this:

Australia, on the other hand, uses AV. Does this help with the disproportionality issue? Let’s draw a similar graph of seats/votes in its past five elections:

Certainly something is different, and the end result is closer to proportionality. It may be that Australia’s electoral politics is very different from the UK’s - but in a way, isn’t that exactly the point? As Tony put it (also on Facebook):

Whether or not it reflects the current political landscape seems to be somewhat of a red herring, as the number and variety of parties is largely going to be determined by the voting system in place, rather than vice versa. (So the argument that it’s OK in NI where there are more/different parties, seems not just wrong, but completely back to front.) If there is a better system in place then it doesn’t just effect how people vote, but will also shape how candidates and parties organise.

Whether AV itself leads to more proportionality, or whether the adoption of AV will lead to a restructuring of electoral politics which in turn leads to more proportionality, I don’t care; what matters it that we get there. That’s why I’ll be voting Yes on May 5th.