Preferential voting for wonks: did the Greens really win Maiwar?

I am a big fan of compulsory preferential voting. I note the informal vote in the Queensland election despite the change from optional preferential was surprisingly low.

The complexity of the current Queensland election outcome reminds me that relevant stuff gets covered by Jordan Ellenberg in How Not To Be Wrong: The Hidden Math of Everyday Life.

Chapter 17: There is no such thing as public opinion. Recommended reading.

What Ellenberg does here is work the numbers differently in a three cornered contest to show that in a close race the eliminated candidate who came third could actually be the preferred candidate over the winner.

Where this could apply in the current Queensland election is the likely Greens win in Maiwar in inner Brisbane. With just a handful of votes splitting them the ALP candidate will likely be eliminated before the Green. The Greens candidate will then surpass the LNP which was a clear winner on first preferences with more than 40% which would have seem them elected easily on the first past the post system in the USA and UK..

However the LNP preferences don’t count at all in this situation. If they did it would be almost certain that the majority of LNP preferences would have gone to ALP over Green as was directed on how to votes. Consequently it is almost certain that the Green is not the most preferred candidate in Maiwar and possibly by quite a long way.

To put this another way. The great advantage of preferential voting is that the votes of minor candidates are not wasted and the result more accurately reflects community opinion. However in this situation it is the preferences of the leading candidate which are actually wasted.

Ellenberg suggests that this situation will tend to discriminate against the more centrist candidate.


4 Comments Leave a comment

    • Ta. Should also be pointed out that the same situation applies to the One Nation win in Mirani. The leading ALP candidate on first preferences would have elected the LNP and not One Nation if their preference was considered. In both places the elected candidate is not actually preferred by a majority but that’s how it works.


  1. It’s just a problem with the way our preferential voting system works. Given that we now have compulsory preferential voting, a simple way around the problem is to just sum the scores (being their number on each vote) of each candidate, and the candidate with the lowest score wins. That way the preferences of all voters are accounted for…but it only works if preferences are compulsory.


    • It’s also always interesting that the significant minor parties promote proportional representation. Basic game theory tells you this results in disproportionate influence for the minor entities who promote it.


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