The changing role of preferences

Just a quick post to draw attention to a really interesting paper presented last week at the Australian Political Science Association conference by Ben Raue, whose work I refer to here from time to time. Here’s his blog post explaining it, and here’s the text of the paper: “Not your parents’ electoral system.”

Raue’s argument is that although the voting system used for the House of Representatives – compulsory preferential voting in single-member districts – hasn’t changed for almost a hundred years, recent changes in circumstances have made it, in practical terms, a quite different system from what it used to be. The rise of independents and third parties has introduced a type of unpredictability that is quite alien to how the system has worked for most of its lifetime.

We’ve noted here before the increase in what the electoral commission calls “non-classic contests”: that is, seats in which the final two candidates are something other than Labor and Coalition. Until recently there were never more than a handful of them, but at last year’s election there were 27, or more than one-sixth of the total. There are also an increasing number of seats that, while they end up as a “classic” contest, could easily go the other way; an independent or third-party candidate is within striking distance of the top two.

Raue has a neat way of demonstrating this latter point, with a graph showing the average gap between the second- and third-place finishers (in three-party-preferred terms). In less than twenty years it’s declined by about ten points, from around 25% in 2004 and 2007 to around 15% last year.

The effect is that, from the voter’s point of view, the way the system works has changed:

When there are only two viable candidates, voters have a clear choice. They can either cast a first preference for one of those candidates, or vote for another candidate and then give a preference to one of those viable candidates, but there is no doubt about where their vote will end up.

But when there are more than two viable candidates, questions of order of elimination come into play, and in theory voters could consider the strategic value of how they vote, casting a ballot for the candidate with a better chance of winning the final preference distribution rather than their favourite candidate.

Raue explains some of the practical issues with this, but as he points out it’s also a theoretical problem about representation. Single-member districts always distort representation, but in a traditional two-party system it’s easier to defend those distortions as the price of simplicity and predictability. The proliferation of three-cornered contests removes those advantages; instead, results are often hostage to the changing fortunes of how-to-vote cards.

Preferences have always mattered in the Australian system since they were introduced more than a century ago. But the voters knew whose preferences would count: it was the independents and minor parties, not the major parties, and if any of them mattered then they all mattered equally. If the identity of the top two candidates isn’t clear, though, then that certainty disappears – the Liberal how-to-vote card, for example, might be critical to a particular outcome, but with only a small change in the parameters it would have had no effect at all.

Results therefore start to appear much more arbitrary. As Raue says, “These results may have been the fairest way to allocate a single electorate, but if you aggregate them over numerous electorates the results look a bit silly.” The solution, of course, is to introduce some form of proportional representation; Raue doesn’t stress that point here, but as a former Greens member that’s clearly what he supports.

It’s well worth reading the whole thing – his colored graphs showing outcomes from a range of three-party-preferred votes under different preference assumptions are particularly nice.