Possums Pollytics

Politics, elections and piffle plinking

The New Pendulums

Posted by Possum Comitatus on January 7, 2008

The AEC has returned the writs, so we now have the complete results for the election.

First up, we can have a squiz at the national pendulum as well as the respective state based pendulums. They’re thumbnails so just click on them to blow them up:

What they show is the number of seats that would fall for a given uniform swing to either major party. To use it, pick a swing on the vertical axis, trace it across until it hits the black line, then trace it up or down to the horizontal axis to see how many seats that swing would deliver to the major party. The national pendulum also has the swings for seats blown up in the top left and bottom right quadrants for swings of less than 7% to make it easier to read in terms of the seats that would change hands for the usual smaller swings.

National Pendulum


NSW Pendulum


Victorian Pendulum


QLD Pendulum



S.A. Pendulum


W.A. Pendulumsfswa1.jpg

The other States and Territories are best given by a table:

Division State ALP Margin
Solomon NT 0.19
Bass TAS 1
Braddon TAS 1.44
Franklin TAS 4.48
Lyons TAS 8.78
Lingiari NT 11.16
Canberra ACT 11.82
Fraser ACT 15.07
Denison TAS 15.63

With the Victorian (and national) pendulum, there’s a bit of a quirk involved with the seat of Melbourne where Adam Bandt from the Greens came second in TPP terms behind the ALP. As a result, Melbourne is sitting on a margin of only 4.71% for the ALP. However, if there were any swing to the Libs of a percent and a bit or more in Melbourne, the Libs would probably end up running second in TPP terms, forcing most of the Green vote to flow to the ALP via preferences and blowing the ALP margin out to over 15 points as result. So it’s best to keep that in mind. These charts will be archived and accessible from the top menu via the 2008 Swings for Seats button.

An interesting thing happens when we compare how many seats each party would gain from a given uniform swing. If you click the thumbnail below, it blows up into a chart that shows the number of seats each party would expect to gain from a given uniform swing.


What this means is that the Coalition gains less seats than the ALP from a given swing. For instance, the Coalition would need a uniform 1% swing to gain 5 seats whereas the ALP only requires a uniform swing of 0.21% to gain 5 seats. If we look at the swing needed for each party to gain 5, 10, 20 and 30 seats respectively we get:

Seats Gained ALP Swing% Coalition Swing %
5 0.21 1
10 1.29 2.05
20 3.88 4.48
30 5.83 6.88

There’s an electoral redistribution due before the next election so this may change a bit, but if the current national pendulum holds it rough shape, the Coalition will find itself in a rather difficult situation, having less fat in the margins of their 30 closest held seats than the ALP does in theirs. One would think that the next election campaign would be an old style battle for the marginals, with the ALP being in the prime position not only because of the pork barreling that government can supply, not only because the ALP will have more to spend as a result of them being in power everywhere, but also because they face the biggest seat bang for the swing buck.

To make it worse for the Coalition, there are 3 seats that the ALP could gain in Qld (the new centre of the government) with a swing of only 0.21%, and in WA where the Coalition hold all but 4 seats, 3 seats could fall to the ALP with a swing of 1.71%. If I were the Coalition, I’d be extremely worried about any potential government consolidation in Qld and a rebalancing of the seat numbers in WA. The ALP can gain seats by basically standing still, having only very small uniform gains in some states delivering the goods. The Coalition on the other hand, as you can see from the chart, find themselves in a much poorer position.

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22 Responses to “The New Pendulums”

  1. It’s all up hill for the man with the hair.

  2. kwoff.com said

    The New Pendulums « Possums Pollytics

    he AEC has returned the writs, so we now have the complete results for the election.

    First up, we can have a squiz at the national pendulum as well as the respective state based pendulums. They’re thumbnails so just click on them to blow them up:


  3. Doug said

    Beyond the redistribution you can be confident that thee will be a third seat in the ACT by the time of the next election – Bob mcMullan will not let them lose sight of that – the coalition refused to deal with the ACT situation when making arrangements for the NT to keep its second seat – probably reasonable given what we now know about under enumeration of the indigenous population in the census.

    The other issue that will impact margins is the likliehood that after the Joint Standing committee on electoral matters has its standard inquiry there will be some legislation to deal with a few of the Coalition’s changes to the electoral act on enrolment issues and provisional votes.

  4. David Richards said

    So The Libs have to campaign their arses off just to preserve their current position, let alone make significant inroads? Couldn’t happen to a nicer bunch 🙂

  5. Paul said

    How many times have first term governents actually gained seats poss?

  6. Possum Comitatus said

    Paul, whether new governments gain seats at the subsequent election is a bit of a mixed bag of late. Federally, new governments don’t tend to increase their majority as can be seen from Mr Mumbles table here:


    But at the State level, it’s becoming almost the norm for new governments to increase their majority at their first election where they have incumbency. Qld did it in 2001, NSW did it in 1999, Victoria did it in 2002, SA did it in 2006 and WA basically stood still in the 2005 state election with both ALP and the Libs picking up seats.

  7. A Parrot Chick said

    On the state graphs… Why dont they go through the origin? Surely a zero% swing gives zero seats gained/lost ?

  8. Possum Comitatus said

    Parrot, they dont go through the origin because there is no 0th seat to fall. Rather there is just the first seat to fall with a swing to the ALP, and the first seat to fall with a swing to the Coalition.

    Those two data points are just joined by a line.

    When the electoral redistribution is done, I promise to add a phantom zero seat so all the lines go through the origin! :mrgreen:

  9. JP said

    Possum, do you know of anyone who has published the new pendulum in the form it’s often done – as two lists of seats in order of increasing margin to each party?

  10. Possum Comitatus said

    JP, I’ve just added a Box.net file widget in the right hand column, just below the archives.

    In that is an excel file of the current pendulum.

  11. JP said

    That was quick! Thanks!

  12. bsfairman said

    Do you see any chance of the house and therefore the senate expanding in this term? Given that a smaller senate quota is in the interest of Independents and minor parties; might now be the time for such a move to occur?

    The cut points are 176 HoR seats with each state have 14 senators (7 elected at each half election) or if they wanted to keep it even 200 HoR seats with 16 senators (8 at each half election). Someone could build an adjustable senate calculator and see how the results would have been with these setups.

  13. Ron said

    Labor could win 10 seats with a 1.30% swing in 2010

    Yet a small 2.10% swing to the Libs wins them power again

    So the swing % is knife edge BOTH WAYS

    The key to 2010 seems to be how the economy is in 2010 especially interst rates & perceptions of labors economic management

  14. Interested spectator said

    Possum, this is off topic, but can you recommend any blogs to get incisive comment on the progress of the US election? No squirrel comitatus?

  15. Doug said


    I suspect that the changes to the Electoral Act on enrolment and provisional votes are made plus a likely third ACT seat, plus the effecto f first time incumbency in the seats one this time, the swing required by the Coalition will be over 3%

  16. David Richards said

    I agree, Doug. Despite the pendulum leading you to the conclusion that The Purple SuperHornet could win with just over a 2% swing, they lose the incumbency advantages – no huge ad campaigns.. no fear campaigns. I would think they would actually require effectively a 4% swing to win. I think they would be lucky to maintain the status quo.. barring some huge cockups by the ALP.. or economic Armageddon . The Purple SuperHornet would have to offer something positive and in marked contrast to the Howard regime, and with the rabid NSW right, and the raving religiosos, that would seem highly unlikely.

  17. Nathan said


    Enjoy the site as always.

    With regard to the ‘just over 2%’ or 2.7% uniform swing figure you’re quoting, I assume you’re putting both independents in the Labor column?

    What’s the basis for that?

    As I understood convention, independents are normally placed in nominal major-party TPP position, which makes New England and Kennedy Coalition seats. That leaves Labor with 83 seats, of which 8 constitute its buffer against a hung parliament. The uniform swing required is thus 1.41%.


  18. Possum Comitatus said

    Yes you are correct Nathan!

    Why I’ve been carrying on with 2.7% is anyones guess :mrgreen:

    Unfortunately this aint the only time I’ve done it in the last few weeks.

  19. Nathan said

    Well, if you make an allowance for incumbency/sophomore effects then 2.7% is probably more indicative. Still not a big number though.

    Landeryou had a piece on this in Dec:


    “The Rudd government is the most fragile first-term government of the post-war era. Even Whitlam in 1972 had a 2.2% buffer to work with (back when Charles Race Thorsen Matthews was last man in defence in 2.2% Casey). Rudd has 1.5%.

    To put that in context, the Brumby government has a uniform-swing margin of 6.3%.

    Iemma government: 6.4%.

    Bligh government: 7.2%.

    Rann government: 9.4%…”

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