Back in the 1970s, when the idea of analyzing voting and poll results in terms of the “two-party preferred vote, it was a major advance. Even though Australia has had preferential voting since (I think) 1921, it was poorly understood, to the point that when a candidate or party with plurality of votes lost on preferences, it was seen as a source of justified grievance (not helped by the fact that both the DLP and the Australian Democrats were splitoffs from a major party that aligned mostly with the other major party).
But that was in the days when Parliaments (or at least Lower Houses) were almost invariably made up solely of members of the major parties. Just as in the 1970s, the facts have changed but concepts haven’t caught up with it. Even though it’s now very common for the government to have a minority of seats, and such governments have worked very well, pundits still treat this outcome as an aberration, a “hung Parliament”. This is reflected in the continued use of the two-party preferred measure, which presumes that the last two candidates in any electorate, after preferences are distributed, will be those of the major parties. So, for example, Green votes for Adam Bandt are allocated between Labor and Liberal parties and used to forecast the election outcome, even though Bandt’s preferences will never be distributed.
There are various ways this could be fixed. The ideal one, in my view, would be to replaced “two-party preferred” with a seat-by-seat allocation of votes to “two most preferred”. That would need big samples to be reliable, but there are a variety of techniques that could be used to mitigate the problem.
The big benefit of this is that we could then see whether or not the poll was predicting an outright majority for one party. Assuming equal luck in marginal seats, a poll giving more than 50 per cent of the “two most preferred” vote to one party would imply a majority of seats for that party.
My reading is that most of the current polling yields a deliberative (or, as our pundits persist in describing it, “hung”) parliament as the central estimate, with enough error to allow either side the chance of majority. Given the likely alignment of independents and Greens a deliberative parliament would probably allow the formation of a Labor minority government. That raises the thorny question of the relationship between Labor and the Greens, which I will deal with in another post if I get time.