New numbers change Victorian federal redistribution equation


Federal redistributions in Australia rely on two sets of numbers – the actual enrolment numbers at the time that the process commences, and an estimate of how many voters will be enrolled at a future point, about three and a half years after the conclusion of the process. While electorates need to be drawn within 10% of the average enrolment at the start of the process, the projected numbers are far more important, since seats need to be drawn within 3.5% of the average on those figures.

These projected numbers ensure that electorates are drawn so that faster-growing seats have smaller populations, and slower-growing seats have larger populations, and thus population change reduces malapportionment, rather than increasing it.

Unfortunately, if those projected numbers are no good, the whole thing is undermined.

The projected figures for the Victorian federal redistribution were released in October, and I posted about them here.

There have been a number of people raising concerns about those figures in the comments, and earlier this week the AEC acknowledged the issue, saying that “The AEC has been informed by the ABS that there was an error in the initial enrolment projections supplied for use in the redistribution of Victoria.” They have now released this corrected data, and it does change the distribution of population in a way that will favour outer suburban growth areas, which will be drawn with smaller electorates than if the original projections had been used.

I haven’t personally investigated the problem with the projected numbers, but as an example Zac Gross posted this graph, showing that almost all Victorian SA1s were assumed to have growth of almost exactly 10%, whereas in other redistributions the growth rates vary (as you’d expect).

First up, I’ve modified the following table that I posted in October which breaks down electorates in Melbourne into different parts of the city north and south of the Yarra River, and breaks rural Victoria into east and west.

The original projections had the 26 seats of Melbourne collectively about three-quarters of a seat under quota, but that deficit was spread out across the city. The 16 seats south of the Yarra were about half a seat under quota, while the 10 seats north of the Yarra were about a quarter of a seat under quota. It was particularly surprising that the six seats of western Melbourne, an outer suburban area where you’d expect fast growth, was projected to barely gain any population relative to other parts of the state. This looked very different to the trends in the NSW redistribution, where Western Sydney is set to gain a seat while the eastern half of the city loses two.

But this picture looks different with the new figures. The ten seats north of the Yarra are pretty much spot on quota, although the central city seats are under quota and will probably need to expand to take in surplus growth in the western suburbs. The 16 seats south of the Yarra are now 84% of a seat under quota, rather than 50%. Indeed the eight seats I defined as “eastern Melbourne” are almost half a quota under themselves.

This makes a huge difference to the implications for the redistribution. It’s now clear that the seat to be abolished will be in the eastern suburbs of Melbourne.

This doesn’t mean that other areas won’t be affected – overall the seats north of the Yarra (urban and rural) fall short of their quota by 17% of a seat. It’s possible this deficit could be spread out amongst the 19 seats on the north side and thus doesn’t require a seat to cross the Yarra, but there will definitely be a need to distribute population differently within that area.

Another way to look at the figures is via this map. It has two layers. The first shows the revised projected quotas for each seat, while the second shows how much each seat’s projected quota was changed by the revisions.

The first map now makes a lot more sense. Most seats in Victoria are under quota (as you would expect when a seat has been abolished), but the outer suburban fringe on the north-west and the south-east both tend to be over-quota. This was not the case on the original figures.

When you toggle to the second tab, it’s very clear that the new projections have favoured outer suburban areas.

La Trobe, Lalor and Calwell were all projected to be under quota but are now projected to be well over quota. The change in La Trobe was 13.2% of a seat’s population!

It’s quite unfortunate that this mistake was made after the first two rounds of submissions, which would have been made based on those projections being correct. The mapmakers will be able to use the correct figures, but will be relying on public submissions based on entirely different numbers. But I’m not sure the alternative of allowing further rounds of public submissions would have been viable. At least the problem has been identified and fixed. It would have been far worse to continue with incorrect numbers, that would have likely led to fast-growing outer suburban areas being under-represented.

Western Australia was also affected by this issue, and I’ve got a blog post coming up covering WA this afternoon.

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  1. The revised enrolment projections make it certain that a seat in Eastern Melbourne will be abolished. Chisholm, Hotham and Aston are all abolishable. However, since Hotham is named after a colonial British male politician while Chisholm and Aston are both named after a woman, Hotham is the name most likely to be retired.

  2. @ Joseph
    I support Hotham being retired at least in terms of name.
    @ John, i think Higgins is less likely as it has natural boundaries like the Yarra River and Gardiners creek. What is the chance Casey will be abolished instead?

  3. @nimalan im now illing to get on the abolish hotham train.
    i think glen eira should be moved in goldstein monash into chisholm kingston into issacs adn dandenong into bruce

  4. cancel on second thoughts given that surplus in holt adn la trobe i might just retire the name as the division will probably still need to exist but given it will face more change then first planned a rename might be order instead

  5. From having a first look at the new figures it would be safe to say that Gippsland, Monash, Indi and Mallee can remain unchanged. Melbourne could stay unchanged if there is no contemplation of crossing the Yarra.
    Interesting to note also that the Corio shortfall and the Corangamite are almost identical so a straight swap might be in order.
    Hotham would seem the obvious candidate for abolition, possibly Higgins but harder to justify with these numbers.

  6. Interesting to note also if that an electorate crossed the Yarra to take in all of Nillumbik, and Melbourne took Southbank and Docklands, you have precisely the 1/4 of a quota needed to have balanced enrolments north and south.

  7. @redistributed given the excess in holt and la trobe i wont be abolising hotham but i will be advocating for a name change given it will lose almost 50% of it current voters

  8. It’s not the first time the ABS has provided the AEC with clearly fraudulent data that bore no resemblance to what was going on at the very local scale required for redistribution, but it is the first time I can recall the AEC actually responding to the public and the Parties calling it out, taking it seriously, and doing something about it. It completely screws up all the public suggestions, and that aspect of it really isn’t good enough, but I’m pleased to see the AEC taking action now before it was too late.

    Credit to the members of the public who made suggestions challenging the projections in an intelligent, informed way – many of them I know have hung out in these threads.

    Those of us interested in how these things are regulated by law really need to be giving some thought to how these processes can be cleaned up to rely less on shoddy work by the ABS, to protect the integrity of electoral boundary redistributions, and to give people (other than the right-wing cookers, who will always cry things being rigged) sufficient confidence in the integrity of these processes.

  9. John
    What do you suggest be abolished? especially now that it is very clear that has to be a division south of the river.

  10. @ nimalan Casey has been moving steadily south – I first voted in Casey in Croydon, now it extends down into Belgrave near where I live.

    It’s a problematic electorate, as the northern urban conservative part has nothing in common with the southern Hills part, which has a substantial Greens vote.

    Not sure how that would be fixed, as we had the same problem when we were the northern part of La Trobe. In some elections, no candidate comes anywhere near us, and no one ever offers anything that actually addresses our issues.

  11. @Nimalan – on the original data I think there was an excellent chance of Casey and McEwen being merged into a single seat around the outer northeastern suburbs and rural exurbs, probably taking the name McEwen, and at least in-name abolishing Casey. This would have been similar to the Labor suggestions, without mirroring it precisely.

    That seems far less likely now. On these new numbers, and given there are now over-quota divisions both to its northwest and south that be shifted to draw new people into Casey, it would be hard to abolish Casey without having something new in its place that would just look too much like the current Casey and having too many of its electors.

    If the commission wants to keep the Yarra as a hard boundary for the divisions nearest to Port Phillip, then they would have the same problem if they tried to abolish Higgins.

    Bruce could be changed could be changed quite radically, yet again, to bring Holt and La Trobe back within the allowed range. Their preferred division name to abolish would absolutely be Hotham. Deakin could get squeezed in practice but the name would probably be retained.

    A much smaller Yarra crossing is now needed with the new numbers. A crossing between Southbank and Docklands is possible, but I’d expect the Commission would prefer it in the Nilumbik LGA as one or a combination of either Casey shifting west into McEwen toward St Andrews and maybe Hurstbridge, or Menzies shifting north toward Eltham in a way that would be similar to the 2019 boundary between Menzies and Jagajaga.

  12. The revised projected enrolment data by SA1 and SA2 has been released by the AEC and can be found here.

    I remember a Tally Room commentator named Kevin Chen developed a Victorian redistribution tool based on the old projected enrolment numbers for each SA2. It would be great if he could redesign the tool using the revised projected enrolment numbers. It would be even better if this tool can allow us to check the current enrolment numbers for each SA2 as well.

  13. based on the fact theres still about 80k voters left in hotham after ive fixed up everything east west and south of hotham i cant see it being abolished. il keep working and get back to you

  14. Adding Upper Ferntree Gulley, Upwey and Belgrave gets Aston perfectly on quota. Casey would need to push into Croydon (Deakin) and Deakin move west into Box Hill, Chisholm down into Monash, Hotham abolished.
    Pearcedale and Tooradin which are in Holt are the perfect size to slide into Flinders (where they have been before).
    It is interesting that with this change the jigsaw pieces are seemingly easier to put together.

  15. @Josh Lucock
    The problem is the shifting across the Yarra has to go the other way. You need to have seats like Jagajaga gain from Menzies, not the other way around. Unless you want to abolish a seat in the west and transfer .74 quotas from the west to the east,

    Some solutions I’ve tried so far

    – .26 quotas pretty much perfectly if you put Warrandyte Nth and everything west of Williamson Rd into Jagajaga from Menzies
    – Some variation of .26 quotas can be achieved by putting Southbank/Docklands and some variation of parts of Melbourne Ports, South Yarra and/or South Melbourne + Warrandyte Nth
    – Around .29 quotas if you do everything in Macnamara nth of the West Gate Freeway + Warrandyte Nth and Healesville and Yarra Valley
    – .2 quotas if you just do Healesville/Yarra Valley + Warrandyte Nth

    Curious what everyone is trying to do with McEwen. I really want to get rid of Macedon Ranges but than where does it go? If you put it into Hawke then where do you put Sunbury?

  16. Based on the numbers I’m looking at a Yarra crossing is still gonna happen. Because even though the defecir in the eastern suburbs has increased the surplus in la Troba and Holt more then compensatesfor that.

  17. Thanks Josh Lucock,
    Abolishing Hotham was my initial preference. I do like @redistributed’s proposal. I actually recommended transferring the Coastal Hamlets in Casey LGA such Tooradin, Cannons Creek etc into Flinders in my submission to AEC. I also recommended moving the remaining Belgrave line suburbs such as Tecoma into Aston. I am keen to hear what others recommend in terms of which seat to abolish.

  18. @nimalan I’m probably gonna stick with jagsjaga but instead of merging it with mcewen this time il merge it with Menzies. Hotham should be saved by the surplus in Holt and la trobe. Although It will she’d theglen eiraand kingst9n lgas. So it will, be a dandenong/Monash seat

  19. Finding it very hard to get La Trobe and Holt to work with their current enrolment being above 90%. You need projected enrolment to be near 103.5% due to their insane population growth. The Clyde North area in particular ruins basically every seat I try to make.

    Same problem with Corangamite and Lalor, though lot as bad, and probably Calwell and McEwen when I get to them.

  20. Interesting to note that under the original figures compared to actual enrollments in December, 6 Seats were over 20% towards the April 28 figures and 12 seats were between 10 and 20% towards they April 28 figures.

    Under the new enrollments, 4 Seats are over 20% of their projected April 28 enrollment figures (Aston, Casey, Gorton and Jaga Jaga with a further 18 seats already between 10% and 20% towards their April 28 figures.

    The time that has elapsed is 7.16% so these seats are clearly shooting their lights out.

    The worst performing seat is Menzies, which since 9 Aug 23 has only increased by 55 electors and most popular seat is Latrobe which has grown 3,007 electors in that time (an increase of 11.39% towards its April 28 figure)

    I still am not sure that in some growth suburbs some SLA’s are projected to grow and the sla next door is expected to decline by 20%, thus I am skeptical about some of the projections for McEwan, which I think are under and the same for some of the other bigger growing seats

  21. @drake I had the same problem with Latrobe and holdout I have the solution. Holt takes Clyde north-north from la trobe. Brucethen takes Hampton Park West and east

  22. As one who spent a significant part of my submission calling out the obviously dodgy projected enrolment numbers, I’m feeling that this revision of projected enrolment numbers basically gives the AEC the excuse to disregard all submissions, go and propose draft boundaries with no alternative input.
    We’ve been disenfranchised.
    Does this call into question the legality of both the Victoria and WA Redistributions?

  23. Thanks John
    In your proposal, does La Trobe keep rural areas like Bunyip/Koo Wee Rup? and Holt the coastal areas?

  24. @nimalan la trobe only loses clyde north-north sa2 to holt thenits at quota. holt only loses hampton park west and east to bruce

  25. Although I am not too familiar Western Melbourne, here is my proposal

    – Gelibrand should had revert back to being an Inner West based seat which should consist of most of Mariboynong council (excluding Braybrook) and the Eastern Half of Hobson’s Bay council given the current boundary puts Outer Suburban new housing estates in the same seat with Inner City Yarraville and Williamstowns.

    – Fraser should had reverted back to becoming a Brisbane based seat but also add in Braybrook since the demographics are similar

    – Lalor should be based on the Southern Half of Wyndham and Western Half of Hobson’s Bay

    – Gorton should removing most or all of the Brimbank part to Fraser but then adds in Northern parts of Wyndham given they gave similar demographics and interest despite being geographically apart
    – Hawke probably does not need so much change but given the seat is over quota they could move Ballan back into Ballarat and/or Plumpton and Hillside into Gorton

  26. @marh Gellibrand will need to expand west to absorb that surplus in Lalor and will then lose its eastern fringes.
    Fraser is in melbourne not brisbane
    Gorton will go unchanged as its pretty much at quota.
    Hawke will shed bacchus marsh surrounds to ballarat and wont need to expand as it will still be within quota range

  27. @ Marh,
    I would like Keilor to go into Maribyrnong as it is as an affluent area with a less diverse and more european population, maybe parts of Greenvale/Atwood can go into that seat as Calwell is over quota.

  28. I wouldn’t say my proposed Gelibrand is low growth given there is actually quite a lot of growth around Footscray and Mariboynong recently. My apologies saying Brisbane, I meant Brimbank.

  29. John,
    The “corner” theory runs into the problem that most of the “corner” used to be in Fawkner,which did not prevent that seat’s abolition in 1969

  30. @sabena still I don’t think any one seat needs to be abolished . I think if they come in from both sides of the Yarra there will be 2 seats that can be merged into one. Il be doing this with Menzies and jagajaga as I think there won’t be any way a Yarra crossing. An be avoided

  31. A redistribution would potentially impact the standings of both major parties. The Liberal Party may notionally hold Higgins, and/or Labor may notionally hold Deakin and maybe even Menzies. It really depends.

  32. @np by what I’m doing the liberal margin should improve in Deakin but Menzies will probably be notional Labor

  33. mathematically speaking Menzies would normally be abolished by what ive done bt to preserve the name of a PM again il abolishing Jagajaga

  34. @ John, Why not keep Jagajaga instead and have Menzies used for Chisholm & Chisholm used for Hotham. Then we can get rid of the name Hotham and preserve an Indigenous name.

  35. It would be nice if there was some explanation of why it took 3 months to admit to & correct a mistake that was obvious at a glance. Some errors in this sort of thing are very subtle, but not this one: it was immediately clear that the numbers were nonsensical. Yet 3 months of silence from the AEC & ABS. Not good enough.

  36. I still think Hotham will be abolished.

    While it’s less under quota than many of its surrounding seats, there were a lot of suggestions to abolish it, the arguments all make sense, and all the surrounding seats which are under quota can quite easily absorb the parts of Hotham that are very well suited demographically (eg. Bentleigh East into Goldstein & Isaacs, Hughesdale in Higgins, Monash into Chisholm, Greater Dandenong into Bruce, Kingston into Isaacs, etc).

  37. Putting Hotham’s share of Dandenong into Bruce makes a lot of sense but it’s really hard to do. Mainly because La Trobe and Bruce contain so many growth areas, you have to draw those seats in an extremely particular way to get current enrolment and projected enrolment within tolerance.

    Gippsland, Monash, Bruce, La Trobe, Flinders and Dunkley have roughly 6 quotas worth and there isn’t a lot of good areas to transfer them elsewhere. Having Isaacs gain from Dunkley causes Dunkley to have to push into Mornington and Flinders right into Cranbourne. The Emerald/Cockatoo areas could easily work with Casey but you almost need to keep it in La Trobe because it’s the rare low growth area that can allow La Trobe to be in tolerance. If someone could get the numbers to work I’d be curious how they did it.

    I had to draw pretty weird boundaries for Calwell and McEwen to keep them within current enrolment too. McEwen basically has to keep Macedon council to allow it to be in tolerance.

    I finished my first rough draft today. I pretty much got away with only really putting Bulleen into Jagajaga. I’ll share a map of it soon. I essentially merged Hotham, Chisholm and Deakin into two seats so I’d just suggest keep the name Deakin and than name the remaining seat after a women.

  38. @nimalan because this way only one needs to change and the rule i usually to preserve th division whose electors have the greatest numbers. ordinarily menzies would be abolihed but because of it being a prime minister it overrules jagajagag besides jagajaga int named after a person but three elders of a tribe.

    @trent the problem with hotham is there is now coniderable excess in la trobe and holt that will need to be aborbed west and north. bruce will need to take territory from holt and holt can take territory from la trobe therefore there is exces needing to go to hotham


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