ABS Population Statistics Confirm Changes in House Representation

(Update 3 July – the determination by the Australian Electoral Commissioner has been published confirming that Victoria will gain a seat and Western Australia and the Northern Territory lose seats. Details here.)

The Australian Bureau of Statistic’s national population report, released this morning, confirms the expected changes to state and territory representation for the next election.

The statistics confirm that Victoria will gain a 39th seat in the House of Representatives, Western Australia will lose the 16th seat it gained in 2016, and the Northern Territory will lose the second member it has elected since 2001.

The statistics in this morning’s report, for the December 2019 quarter, will now be used by the Australian Electoral Commissioner to make a formal determination on 3 July setting down the number of members to be elected from each state and territory at the next election.

When implemented, the changes will reduce the size of the House of Representatives from 151 to 150 seats and begin the process of electoral boundary re-drawing in Victoria and Western Australia. In the case of the Northern Territory, the existing seats of Lingiari and Solomon will be merged as a single seat with revived name Northern Territory.

However, a bill has been moved in the Senate designed to save the Northern Territory’s second seat. While the Constitution determines the allocation of members to states, representation for the territories is determined by legislation and can be changed by parliament.

I have published two recent posts on the allocation of House of Representatives seats. The first deals with the constitutional law around state representation, the second with territory representation including some suggestions on changes that can be made to the formula for territory representation.

My calculations of the seat entitlements based on this morning’s ABS report are shown below. Update – the table below has been updated with the Electoral Commissioner’s official determination.

House of Representatives Seat Entitlements

Population Quotient Seats Change
NSW 8,128,984 47.11443543 47
VIC 6,651,074 38.54867921 39 +1
QLD 5,129,996 29.73272740 30 ..
WA 2,639,080 15.29573244 15 -1
SA 1,759,184 10.19598033 10 ..
TAS 537,012 3.11244520 5 ..
ACT 429,179 2.55164379 3 ..
NT 247,225 1.43319972 1 -1

Note: the above table and notes below have been updated based on the official release of the Australian Electoral Commission’s determination.

Under the formula, Tasmania would only be entitled to three seats but is guaranteed five seats by Section 24 of the Constitution.

ACT figure shown in the above table includes Norfolk Island (1,724), while the NT includes Christmas Island  (1,956) and Cocos (Keeling) Island (563).

Both territories can have a statistical error margin applied to their quotients to determine eligibility. The application of error margin was not enough to allow the Northern Territory to retain its second seat.

In the introduction to this post, I mentioned my previous post on Territory entitlement to House of Representatives seats.

In the post I put forward two methods of allocating seats discussed in United State’s literature on the apportionment of seats to states.

Both of those methods would allocate two seats to the Northern Territory and three seats to the Australian Capital Territory.

Under the Huntington-Hill method, currently used for US apportionments, the Northern Territory’s quotient would be above the required 1.1412 1.4142 and the ACT’s above 2.4495.

Under my preferred Dean’s method, designed to allocate seats based on minimising the difference between average population per member and the national quota, the Northern Territory would need to be above 1.3333 quotas and the ACT 2.4000.

Likely Impact of the Western Australian Redistribution

Reducing from 16 to 15 seats will have a massive impact on WA electoral boundaries. The table below shows variation from quota for the 16 current seats based on the new 15 seat quota of 111,700 in current enrolments.

Seats have been broken up into Country, North Perth (ie north of the Swan) and South Perth. Pearce is shown as a mixed seat as it crosses the Darling Range to include the Avon Valley. Hasluck is also listed as mixed as it runs along the escarpment covering areas roughly north and south of the Swan.

When the new boundaries are drawn, all electorates must be within 10% of the quota, but also within 3.5% of the projected quota in 3.5 years time. When released at the time of the redistribution, the narrow projected quota will have greater impact on drawing the boundaries than the current enrolment.

WA Redistribution – Current Enrolment and Variation from new 15 Seat Quota

Electorate Region Enrolment
(31 May 2020)
from Quota
Durack Country 98,317 -12.0
Forrest Country 106,807 -4.4
O’Connor Country 101,754 -8.9
Hasluck Mixed 100,311 -10.2
Pearce Mixed 124,659 +11.6
Cowan North Perth 100,251 -10.3
Curtin North Perth 101,693 -9.0
Moore North Perth 102,210 -8.5
Perth North Perth 103,485 -7.4
Stirling North Perth 102,832 -7.9
Brand South Perth 109,919 -1.6
Burt South Perth 108,563 -2.8
Canning South Perth 109,442 -2.0
Fremantle South Perth 108,514 -2.9
Swan South Perth 102,232 -8.5
Tangney South Perth 94,619 -15.3

My rough guess on the above numbers is that Pearce is highly likely to lose its rural areas in the Avon Valley to shore up Durack and O’Connor. In southern Perth, Canning may also lose its more rural end and become more urban.

This is shown in the map below. Dark blue is more than 10% under, light blue 5-10% under, pink 0-5% under and orange > 10% over.


Durack in dark blue and O’Conner in light blue (though my blogging software has turned it mauve) both need to gain voters, most likely from Pearce (dark orange). Forrest based on Bunbury and Canning on Mandurah are also in the 0-5% under range.

Which brings me to the second map for Perth.


Three seats are more than 10% under, Cowan in the north, Hasluck in the east and Tangney south of the Swan The other four north Perth seats are also 5-10% under, as is Swan south of the river, while Fremantle, Burt, Canning and Brand are all 0-5% under.

Everything in North Perth can be dealt with by unlocking urban parts of Pearce (orange). Pearce includes all the beach suburbs north of Burns Beach as well as rapidly growing Ellenbrook in the Swan Valley. If the rural parts of Pearce are removed, what’s left can’t include both the northern beaches and Ellenbrook as this would have too much population growth in one seat. Cowan, Stirling and Moore could move north to swallow the northern beaches, leaving Pearce to be based on Ellenbrook, the Darling Range suburbs and Guilford.

That would leave one of Hasluck, Burt or maybe Tangney to be abolished. My guess on a last on first off basis is that the name Burt would disappear.

However, the boundary changes in this process would be enormous, and my guesses are not based on projected enrolments. Whichever seat is abolished, at least half of Perth’s seats will undergo massive change, altering their political complexion.

Redistributing Victoria

Redistributing Victoria will also produce major boundary changes, though for different reasons. Victoria was redistributed only three years ago, so there are no obvious hotspots where a new electorate can be carved from others. Rather, boundaries will start being drawn from the rural corners of the state, then along Port Phillip Bay and the Yarra (electorates rarely cross the Yarra), and successive nips of excess population will create a new electorate, probably somewhere in north-west Melbourne.

But fitting in a new electorate will produce much more extensive changes than were caused by the 2017/18 redistribution.

The map below shows the over and under enrolments in rural Victoria based on a new 39 seat quota. Orange is >6% over, paler orange 3-6% over, light blue 0-3% over, and dark blue is under the new quota.

Gorton in Melbourne’s west, as well as  Ballarat and Corangamite in Western Victoria are all more than 6% over quota, as is La Trobe east of Melbourne. Everything else west of Melbourne is also over quota, so there is likely to be a drift of western Victorian seats away from Melbourne’s western edge. That starts to create room for a new electorate.

For the Liberal Party there is a problem in Eastern Melbourne as shown below.

The Liberal seats of Kooyong, Chisholm, Deakin and Menzies are all under quota, as are the Green seat of Melbourne plus Labor’s Scullin, Jaga Jaga and Hotham. All the light blue seats are 0-3% over quota and light orange seats 3-6% over-quota.

The projected enrolment statistics used in drawing the boundaries will amplify the discrepancies between seats. Everything in eastern Melbourne will need to expand, and that is likely to soak up a lot of the excess in the growth corridor in south-east Melbourne.

Everything points to a new seat being drawn in Melbourne north-west, but achieving that will involve a lot of other seats shifting around.

The table below shows the current enrolment and % variation from the new 39 seat enrolment quota. You can sort the statistics by electorate name or variation.

DistrictEnrolment% Variation
La Trobe115,840+6.6

6 thoughts on “ABS Population Statistics Confirm Changes in House Representation”

  1. Hi Antony, love your work as always! Given the figures you gave in your part 2 post on apportionment, I think you’ve mistyped what the Huntington-Hill quotient for the NT would be here as 1.1412 rather than what you gave in that article as 1.4142.

    COMMENT: Corrected. Miss-typed the square root of two.

  2. Antony, I think your thinking concerning Western Australia reflects your youth and inexperience. It would be unconscionable to retain Stirling as an Division name. It’s named after James Stirling, founder of Perth and infamous for the 1834 Pinjarra massacre in which at least 70 indigenous men, women and children were murdered. Its 2020 and I’m certain that the electoral commissioners will retire the name of Stirling, an electoral Division since 1955.

    At the commencement of a redistribution, the first task of the commissioners will be to estimate the period for which the redistribution will last. I’d expect no future abolition in the seven years following the completion of this redistribution, (around eight years from now)

    It also makes sense to see a dividing line between north and south as running along the Swan River. At the northern end only Durack is a non Perth seat. At the southern end you’d include Forrest and O’Connor. Next, I would assess which seats are likely to be significantly below, around or above quota at the projected date which should be around the end of 2024.

    As you have written, Pearce will be dramatically over quota, even with the transfer of its rural component to Durack. Pearce is also a Division with two high growth areas: the northern section of Wanneroo LGA and Swan LGA which will have to be separated from each other and combined with lower growth areas.

    I also expect that the Divisions of Fremantle, Burt, Canning and Brand will be at quota or above the future projected quota. As it happens, I expect a Wanneroo Division, (coastal Pearce moving into Moore) and Swan LGA moving into Hasluck with Stirling being abolished. Its wonderful that in this instance, the unpalatable seat name also happens to be the logical Division to go.
    Shane Easson

    1. I would rather expect the electoral commissioners to concentrate on creating logical boundaries rather than indulge culture warriors. Like most historical figures James Stirling has a mixed record but he represents a significant part of WA history, That said, the seat names that should be preserved regardless of boundary changes are those that commemorate former Parliamentarians – Curtin, Hasluck, Pearce, Forrest, Tangney, Brand and Cowan (as do Durack and Burt less directly).

      COMMENT: There has been some shift on naming. The last Victorian redistribution re-named Batman and McMillan for similar issues that Shane mentioned for Stirling. And in SA, Wakefield was re-named Spence on criminal history grounds at the same time as the redistribution abolished Port Adelaide.

  3. what if the aim was to make the quota 100000……. and thus increase the size of parliament

    COMMENT: I can’t imagine at the moment anyone is going to propose increasing the size of the Parliament.

  4. The perennial problems of the Western Australian non-Perth population being enough to warrant three and a half seats, and Perth’s donut shaped population growth emerges with a vengeance once again.

    Anthony, in the (unlikely) event that ScoMo decides to go early and the redistribution is unable to be completed, what would be the mini redistribution in WA be. I’m assuming on the numbers, it would be Tagney-Swan beating out the prospect of a supersized Durack-O’Connor (for now). I’m also assuming the 2->3 electorate split in Victoria would be Corangamite-Ballarat.

  5. Is Shane serious? Burt is currently named after a slave owner and yet the left would rather abolish Stirling. If Stirling was renamed a large number of suburbs and even an LGA would have to be renamed. Captain Stirling was the first governor and founded Western Australia. Should we renamed Curtin because John Curtin interned people in unpleasant conditions during World War 2.

Leave a Reply