Sometimes niche electoral theory issues can jump into the spotlight in surprising ways. Normally, the question of how to predict new margins for an independent whose seat has been expanded would only interest redistribution wonks and the relevant campaign teams.
Yet following the draft redistribution of Victoria, it’s been central to a high-profile, apparently short-lived push for former treasurer Josh Frydenberg to run again in Kooyong. The basis for the push was never sound.
The next election will be held on new boundaries in New South Wales, Victoria and Western Australia, provided it is called after mid-October 2024. These boundaries are determined by redistribution committees, not the Australian Electoral Commission (AEC) as such, though the AEC supplies two of the four members of each. The draft boundaries will be followed by fresh consultations before binding decisions are made — decisions that are often slightly different to the draft, but seldom greatly.
In Victoria, a seat must go and the seat the draft abolishes is Higgins, won by Michelle Ananda-Rajah for Labor in 2022 after 70 years of Liberal victories. The voter base of Higgins would be split between five existing divisions, with about 30,000 voters placed in Kooyong, leaving Ananda-Rajah and the Liberals’ Katie Allen looking for somewhere else to run unless the change is overturned (the odd shape of Kooyong has had some comments).
As soon as the draft was released, claims started that Kooyong (held by independent Monique Ryan with a 2.9% margin) would become notionally Liberal or at least much closer, and Liberal preselections should reopen so Frydenberg could return. These were bolstered by a margin estimate of 0.8% by Antony Green, later retracted. Meanwhile Ben Raue had produced a very different estimate of 3.5% and further explained his reasoning in an X thread.
Why did these assessments vary? Frydenberg’s boosters only had eyes for Toorak and Malvern, ignoring that Kooyong would also gain parts of Armadale and Prahran where the Liberals had been trounced. Also, there is no defined, good method for projecting Ryan’s vote in areas o