Australia 2019 Archive


QLD, TAS & NT federal redistributions – estimates of margins

In recent months, federal redistributions have been completed for Tasmania, the Northern Territory and Queensland, with Queensland’s being finalised on January 5.

As far as I can tell, no-one else has published margin estimates for the five Tasmanian seats and the two NT seats. Antony Green has published his estimates of the Queensland margins here. You’ll see that my estimates don’t diverge by much – by 0.1% per seat on average.

I have recently been calculating my own redistribution margins as part of the process of transferring booths so that I can produce maps for the new boundaries as part of my guides. This time I decided to use a new methodology which should be more reliable and quicker.

The AEC publishes data on how many votes were cast at each polling place (and each method of special vote) from each SA1 – the smallest area used for Census data. The AEC also publishes a list of every SA1 and which electorate it has been moved into (and out of) for each redistribution.

Using these datasets, it’s possible to quickly take the results of each booth, split them up in proportion to how much of that booth’s voters have been redistributed, and calculate new totals.

This is superior to my old methodology, where I would move booths according to which seat they lie in. Unfortunately this did not take account of small shifts where no booth moved, or where a booth was right on the border. I would have to guess how much of the booth’s voters would’ve shifted. The new method uses the actual AEC data. It is also a better solution to moving special votes. I’ve traditionally taken an even proportion of all special votes, even though this includes a bunch of pre-poll booths which are distributed across a seat. In practice these pre-poll booths would likely take more voters from one area than another, so distributing their votes according to the actual homes of the voters is far superior.

As to the results of these redistributions, 12 Queensland electorates experienced no change at all. Not one of the 37 seats has changed party. The biggest change has taken place in Lyons, with the Labor margin strengthened from 2.3% to 3.8%. The second biggest effect was in Blair, where the Labor margin was cut from 8.9% to 8.1%.

The five most marginal seats in these three jurisdictions did not experience any change. There was no boundary change in Flynn, Longman, Forde or Herbert, and the minor change to Capricornia had no impact on the seat’s margin.

The full list of margins are below the fold. I look forward to using this new method to quickly calculate margins for the three remaining redistributions (Victoria, SA and ACT) when the draft boundaries are released in coming months.

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Queensland federal redistribution finalised

Six Australian states and territories have been due for federal electorate redistributions during the current federal parliamentary term – we’ve already completed the process in Tasmania and the Northern Territory, and the process was well under way in Queensland.

It turns out that the final decision for the Queensland federal redistribution was announced on January 5. The decision appears to be exactly the same as the draft map, which I blogged about in October.

You can download the boundaries file from the maps page, and you can see how the boundaries have changed in the below map.

This redistribution was one of the most subtle in recent years. Twelve out of 30 seats experienced no change, while the other 18 mostly experienced minor changes.


QLD federal redistribution – draft released

I’ve been quite busy recently and hadn’t had time to deal with the recent draft released for the Queensland federal redistribution.

To be honest it’s the least interesting redistribution I’ve encountered in the nine years I have written for this blog. Queensland is maintaining its 30 federal electorates after a series of rapid redistributions which repeatedly increased its seat numbers. Twelve electorates were left entirely untouched, and most of the others underwent very minor changes.

Antony Green has analysed the boundaries and made estimates for the electoral boundaries. No seat flipped party, although a few have a changed margin.

You can now download my boundary map for this draft proposal.

I have also recently updated a number of other maps: the final Tasmanian federal map, the final NSW local government boundaries as of 2017, and the New Zealand electoral map updated to reflect the results of the 2017 election. You can download them all from the maps page.


Tasmanian federal redistribution – let’s try that again

Tasmania is currently undergoing a redistribution of its federal boundaries – the second of six federal redistributions due during this parliamentary term. The boundaries will also apply to Tasmanian state lower house elections, but probably not until the 2022 state election.

The draft boundaries were released earlier this year, and they saw a few significant changes. The seat of Bass, which covers most of the Launceston area, retracted in to just cover areas surrounding the Tamar river, losing the north-eastern corner of the state. Lyons underwent changes in a number of areas.

It is standard practice for federal redistributions to go through two rounds of suggestions and comment, followed by the release of a draft map, then two more rounds of objection and comment, followed by the release of the final boundaries. This time, however, the AEC has chosen to open up another round of objections and comment, as the boundaries released today were significantly different to the first draft.

No changes were made to the boundaries of three of the five seats, but there were significant changes to the Bass/Lyons border. Bass regained the Dorset and Flinders council areas in the north-eastern corner of Tasmania, and lost the small part of the Meander Valley council area contained within the Launceston urban area. This area was contained in Bass at least since 2001.

At the other end of the state, the Hobart-area seat of Denison has been renamed Clark, after Andrew Inglis Clark: state Supreme Court justice, Attorney-General and one of the inventors of the Hare-Clark voting system. This followed a campaign to change the seat name, including from sitting MP Andrew Wilkie and his predecessor Duncan Kerr.

You can download the new boundary map here, or view the three versions of the boundary on the below map:

I’ve seen some commentary expressing frustration about the removal of the urban parts of the Meander valley from Bass, sticking them in an electorate which stretches to the edge of Hobart.

Unfortunately it isn’t possible for Bass to contain both the Meander Valley area and the Dorset/Flinders corner without pushing Bass over quota.

Based on projected 2021 enrolment figures, Bass must lie within 3.5% of the average. In real numbers, they must have between 74,289 and 79,677 projected enrolment. Bass is projected (as drawn) to have 75,653 voters.

There are three areas which have been moved between Bass and Lyons – the Meander Valley area on the south side of Launceston, the Dorset/Flinders corner of the state, and the West Tamar area which was moved from Lyons to Bass in the original draft and remains there. Each has between 5867 and 7828 voters as of 2021, and if all three were included in Bass it would be more populous than is permitted.

So the original Redistribution Committee decided to make Bass more of a Launceston-based electorate, moving the rural north-east into Lyons, and the augmented Commission has instead decided to make Bass follow local government areas, leaving part of the Launceston urban area in Lyons.

So now there is time for interested parties to argue the case. Theoretically they could also decide to completely reverse the Lyons-Bass border back to its previous boundaries, putting the West Tamar back into Lyons, but this is unlikely.

Bass second draft74,46775,653
Lyons second draft75,50878,313
Meander Valley (Bass to Lyons)6,8407,233
Dorset/Flinders (Bass to Lyons to Bass)5,8495,867
West Tamar (Lyons to Bass)7,6757,828
Minimum enrolment67,51374,289
Maximum enrolment82,51579,677