Sep 28, 2011


Australian federal election simulations and polling trends

Possum Comitatus — Editor of Pollytics

Possum Comitatus

Editor of Pollytics

With a bag of polling data bursting at the seams, it’s that time of year again where we not only update our Pollytrend metrics, but run some election simulation goodness to see how the polling data for the last three months would have played out if it was reflected in any hypothetical election.

We have the usual Newspoll and Nielsen polls for the simulations, plus a Galaxy for Qld, a couple of unpublished national polls  and unpublished NSW and Victorian polls – giving us an aggregated sample size just shy of 15,000 over the quarterly period from July 1st through to last Tuesday. (made up of around 11,900 from the published and 4000 odd from the others – where there’s nothing significantly  different in those unpublished jobbies that we aren’t seeing in Newspoll, Nielsen and Galaxy anyway, it just tightens up our uncertainty a bit)

First up,  the trend measures.

Last month’s Pollytrend update saw a small movement back to Labor – small, but the largest movement towards them that they had experienced since the election last year. Suffice to say, that movement back to the ALP troughed out and is now in slight reverse.

The current point estimates on the trend have the Coalition sitting on 57.3% to Labor’s 42.7% on the two party preferred.

On the primary vote trends (conveniently available on the sidebar to your right) we have Labor bouncing around in palliative care on 28.3, the Coalition hanging around 48.7 and the Greens moving up a point or so over the last month to come in at 12.3. This gives us a whopping 9.7% primary vote swing against the government, washing  out into a 7.5% two party preferred swing towards the Coalition (off the back of a 5.1% primary vote swing towards the Opposition). The Greens meanwhile are slightly ahead of their 2010 election results by 0.6%.

Looking at the longer term primary vote trends, we get:

Nothing particularly exciting there (especially if you happen to be the ALP!), except to note that the big ALP crunch on the primary vote came back in the May to July period and has been pretty much faffing about ever since. That primary vote level is roughly what we saw Labor achieve at the last NSW State election and, barring Campbell Newman getting caught riding a Citycycle naked through Queen Street Mall in the middle of a crack bender, it’s similar to what we’ll also see Labor achieve at the upcoming Qld state election

Next up – the election simulations. Monte Carlo based, state swing focused simulations using our quasi-event dependence framework etc etc.. you’ve heard the spiel before. This time we’re updating the system to incorporate the new electoral redistributions as outlined by Antony Green over at his place.

If you’re an ALP member – probably best to look away about now. If you thought those trends were bad, you ain’t seen nothing yet.

If you’re a Coalition member, well then – break out the popcorn!

The raw state swing data from the aggregated polling looks like this:

The whole country has moved blue since the election, with SA and NSW leading the charge against Labor. WA (the home of Stephen Smith – being spruiked as a possible Gillard replacement by the very people that caused this mess in the first place) comes in showing the smallest swing against the government.

Starting with the basic distribution of the results  of a hypothetical federal election held during the last 3 months (usual caveats of the election results matching the polling data etc – the simulations stabilised out around the 20,000 iteration mark for those in to such nerdery), looking at the number of seats won by the ALP, we have (click to expand)

It’s showing us a result clustered around the 41 to 44 seats won mark in a Parliament of 150 – between 27% and 29% of the seats available. That would give the Coalition around 103 to 107 seats, depending on how they fared against the Indies.

Changing the format of the charts, so it tells us the implied probability of the ALP winning *at least* any given number of seats, starting with the full distribution, we get:

The ALP is rock solid up to winning at least 38 seats, before the distribution starts falling away.

Zooming in to the key results to have a closer look:

The most likely result is the ALP winning at least 42 seats, with an implied probability of 61%. The 43rd seat mark was sitting just under the 50% threshold at 49.5% implied probability. The implied probabilities then start to fall off a cliff, with only a 38% likelihood of getting that 44th seat.

Now here’s where the ouch factor comes in. Comparing the September simulation with the June and March simulations, we can see how the likely number of seats that the ALP would have won have dramatically reduced as the months have rolled on. We’ll run that chart above (giving us the implied probabilities of the ALP winning at least X number of seats) overlayed with the same charts from the last two quarterly simulations (click to expand)

To use an example to explain it – in the March quarter, there was a 60% implied probability of the ALP winning at least 68 seats. By June, that 60% implied probability level had reduced to 52 seats. Now in September, it’s sitting on 42 seats – a full 26 seat contraction over the year from an already election- losing position.

At the critical 50% threshold level, it went from 69 seats in March, to 53 seats in June, down to 42 seats now (as the 43rd seat is just below the 50% implied probability mark) – a 27 seat contraction at the critical 50% threshold.

So what seats would be lost?

I’m going to do something I rarely do and post the individual seat baseline implied probabilities from the simulation. The reason I rarely do this is because it gets taken out of context too often. So to hopefully reduce the likelihood of that happening, it’s best to give a long explanation of what it means.

The simulation results are based on the statistical sledgehammer of monte carlo simulations applied to state swings (with a quasi-event dependency framework so that individual seats aren’t treated as independent events, but are semi dependent on clusters of seats within each state that exhibit historical correlation from the mean state swing, as well as an overarching state swing quasi-event dependence). We need a quasi-event dependence with simulations like this to reflect observable reality and to prevent our results from becoming what is a technical term known as “horseshit

The reason we use the swing of federal polling in each state as the main driver for the simulations, is simply because the best predictor of the result of any given seat at any given Federal election, is the swing at the state level of that federal election that such an “any given seat” happens to reside in.

Seats swing together more at the state level than at the national level – where a perfect example is the 2010 Federal election. Victoria, South Australia and Tasmania had a swing towards the ALP, while the rest of the States had a swing towards the Coalition.

It’s this state based nature of the simulation, as well as its accommodation of uncertainty (both the standard deviations of the swing within each state and the uncertainty of the polling ) and the quasi-event dependency framework (that allows seats to move together on the basis of both history *and* any localised, regional polling results within a state) that makes it at least as accurate as a standard pendulum approach, usually more accurate (sometimes much more) – but never in the last 20 years of elections I’ve retrospectively applied it to for testing, has it been less accurate than a standard pendulum approach.

The ordinary election pendulum has the property where a swing of 5% doesn’t mean that every seat under a margin of 5% will change. What it means is that the average swing would be 5% and that for every seat under a 5% margin that doesn’t change hands, some seat above the margin will swing by more to make up the weight.

The simulations exhibit this same property, but at a state level.

Using an example – let’s say the South Australian seat of Adelaide held by Kate Ellis. Adelaide sits on a margin of 6.1% and South Australia is facing a swing of 8.8% against the Labor Party, meaning that a uniform swing would see this seat fall to the Coalition and be held by them on a margin of 1.3% . If Kate Ellis managed to hold the seat, then some other seat or groups of seats would need to swing more to make up the weight to give us the average swing.

This seat currently has an implied probability of ALP victory of 36.7% based on this quarter’s polling results.  That doesn’t mean that the actual, real life probability of Kate Ellis winning her seat is exactly 36.7%. What the 36.7% implied probability represents is the generic starting probability based on the state swing, the historical variance of the seat of Adelaide in terms of the state swing and geographical factors (in this case, being a capital city seat) with all else being equal.

Of course, not all things are equal.

Most seats have varying numbers of local issues running at various strengths, which will impact the swing in a given seat. Occasionally that impact is large, but often it’s either not very large, or different local issues end up cancelling each other out in net terms as candidates stake out their local issue grounds and it becomes a game of swings and roundabouts, pardon the pun.

Sometimes, opposition candidates end up being complete duds that act to reduce the swing in a particular seat.

Sometimes, some local members are strong local members.

Going back to our example of Adelaide,  Kate Ellis is a strong local member, so that would increase her actual probability of holding the seat beyond the generic probability. By how much? Maybe 10 to 15% – looking back at previous elections, strong local members seem to have around a 10-15% boost in implied probabilities of holding their seats.

However, in any given election, for any given seat, the state swing  – particularly a big state swing – will generally take out those before it in a manner highly correlated to their generic, seat based, implied probability.

The implied probability of winning is effectively a measure of the *distance* between a given seat’s margin and the swing we are seeing, controlling for what we know (geography, historical variance and historical behaviour) and what we think we know (the actual state swing itself). What it doesn’t take into consideration is local and seat dependent issues at the individual seat level.

Anyone using the results below inappropriately, without taking all that rant into consideration, will now be sent to the naughty corner 😛

So, this is what the implied probability of the ALP winning the seats they currently hold looks like if an election were held during the last three months. I’ve only listed ALP/Coalition head to head seats for the mainland states, and no Coalition held seats are listed because the ALP would only pick any of them up on these polling results through some black swan event.

All up – 14 kinds of gruesome for Labor.

BTW – dealing with a spam problem, so some of the comments from new posters might be held up from appearing for a small amount of time.

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35 thoughts on “Wipeout

  1. John Of Melbourne

    Hi Poss, can you please update this page with the new poll results.

    Thanks heaps.

  2. imacca

    Found it via twitter and PB. Thanks Poss.

  3. imacca

    Hey Poss! Any chance you will be updating the polling tracks soon??

  4. nathan

    Hi Possum,

    Re your state swings…

    If you take a weighted average of NSW, Vic, Qld, WA and SA (weighted by population), you get an overall swing of -7.1%.

    But you have an actual nationwide swing of -7.5%.

    That implies a swing in Tasmania, ACT and NT of -13.6%.

    Is that what you think the actual swing is?

    Or are the nationwide and state swings calculated using different processes, and not intended to square up?


  5. armchair opinion

    @ 30 “…It’s not the stock markets fault…”

    No, but it goes to whole greed is good culture of those who are wealthy enough to invest in the stock market. A few people make squillions and there is a huge gap between the wealthy and the poor. It is also very much the privatisation of profits and socialisation (to the poor and middle class taxpayers) of losses, where people are toiling away to pay for the misdeeds of the wealthy who have brought the world to financial crisis point.

    Ordinary people are sick and tired of propping up the wealthy in society, those who don’t do physical work, they think they are too smart and rich, they work their money and they are a parasite on everyone else.

    Perhaps they should stop with the tax breaks for business and the wealthy and start making them contribute more to the economies that they benefit from. Why should the middle class bear the brunt of capitalism failure? Ordinary citizens are angry, jobs can’t be found for their young but they want the parents to make even more sacrifices by paying increased tax for the wealthy to fleece everybody again. Change the system, is what people are saying, make the wealthy pay for their own greed, not those who have been working hard and doing the right thing.

  6. Archer

    Posted October 7, 2011 at 8:59 am | Permalink

    “I hope we have Occupy Wall St protests.”

    Yeah, and perhaps we could have socialist millionaires like whoever is left of Peter, Paul and Mary to come down and sing “This land is your land” to all the people who lost all their money in bad investments. Now that was a priceless piece of vision off the news.

    It’s not the stock markets fault.

  7. Archer

    Posted September 29, 2011 at 9:37 pm | Permalink

    “Poss, is there a direct negative correlation between the primary vote for the Coalition and IQ? Why have we become so stupid, insular, ignorant and fearful? Please tell me this isn’t so.”

    And so it goes. Why do you assume conservative / coalition voters are stupid? Why do you assume converts are stupid? As I’ve been told by others on this blog I don’t seem to be “intellectual” enough to understand. Going against your stereotype, I am well traveled, the son of migrants, speak two languages and have worked over seas. Probably less phobic than many on “your” side of the political spectrum. It is that travel and work experience that has opened my eyes to the idiocies of left wing socialist style governance in European countries and we seem to be heading in the same direction. In our case it is a case of “if it moves, tax it”. Greece, Italy, Spain, Ireland, Portugal and France isn’t looking all to steady. For God’s sake don’t quote Norway etc because they float on oil and even they have a large aging population which will need to be cared for by an ever dwindling younger work force. How do I know? I worked there and made friends with a local politician who carefully followed the news and admired John Howard and Peter Costello’s policies

    And not only on the subject of fiscal policy but on immigration and asylum seekers. There are far right political parties forming all over Europe because they are scared of the loss of their sovereign identity. I’m not talking Geert Wilders right, far more to the right, and they are gathering a following. This government can’t create a policy to implement, and to blame Abbott is childish. He is not running the country, they painted themselves into the corner, they can get themselves out. Do something now before the nutters come out of the woodwork.

    Do you want to know why they are turning to the coalition? It’s easy.
    1/ They don’t give a damn about about global warming any more.
    2/ They have no confidence in Gillard.
    3/ Rudd is lurking in the background.
    4/ They hate this marriage with The Greens. (Love the way Martin Ferguson slaps them down when they mention replacing the coal industry)
    5/ Oakshcotte and Windsor have betrayed their electorates.
    6/ Wilkie is holding the pokie clubs to ransom
    7 We won’t go through the mistakes made during the Rudd period. We were to busy “Moving forward” because they didn’t want us looking at the past.

    There has always been a strong conservative supporter base. I suppose the philosophy is self determination and minimal government. A carbon tax, alcopops tax, plain packaged cigarettes, mining tax and now consideration being given to a fat tax?
    Julia, get out of our lives. There’s another reason why people are deserting the ALP.

    And I doubt that Rudd will be back. The independents and the Greens have made their deals with Gillard. If Rudd gets back in those deals maybe jeopardized and there is one mp threatening to quit thus calling a by election.

  8. JamesK

    Presumably jak is yet another ‘brave’ rebellious inane leftist pro big government anarchist.

  9. Jak

    I hope we have Occupy Wall St protests.


  10. Jillian Blackall

    I strongly doubt the Coalition will win Werriwa.

  11. daretotread


    Well done indeed!!!!!!!

    Only just found it.

  12. Dr John

    Psephology is certainly not my strong suit but I often work successfully on hunches in life (eg.$5.00 Ted Baillieu) and I feel that the current Federal Coalition popularity levels are quite soft.
    Albeit up against a hostile media, both private and public, Labor have it all in front of them and much smooth water potentially presents.
    Could you maybe give a little ground on your title ‘Wipeout’. Interested in your thoughts.

  13. Jean

    Possum- and all the gang.

    Would there be any advantage for Labor in timing some rejectable legislation to trigger a double dissolution close to Oct 2013?

  14. John64

    @CML: Tony Abbott’s already self-destructed. He’s tripped over himself more times than you can count with fingers on two hands. The problem is, he’s not the Prime Minister so nobody’s listening – because Julia Gillard’s tripped over herself just as often, if not more. Make no mistake, this isn’t a massive vote /for/ the Coalition and Abbott, this is a massive vote /against/ Labor and in particular Gillard.

    @Christopher Dunne: And I suppose you think sending Asylum Seekers to Malaysia in a 5:1 swap is a great idea?


    And I suppose JamesK believes every bit of rubbish Limited News tells him to.

    Climate change is not real, it’s just dodgy scientists scamming the system, the BER was a monumental waste of money,insulating homes was a total waste of stimulus money,the GFC didn’t happen, and our public debt is so huge we will all die if the Liberal’s don’t kick out the government, and Carbon Tax will kill every business too.

    And what is offered by the Coalition? Nothing but “no” and figures you can drive a convoy of idiots through.

    I despair.

  16. CML

    Thanks Poss – even though it is a thoroughly depressing read. At least Labor has another two years before they have to test your numbers. Hopefully things will improve, we will get Kevin Rudd back in charge, or Tony Abbott will self destruct. One can only dream!!

  17. JamesK

    Poss, there obviously is a direct correlation between the ALP ‘recalcitrant-intansigent’ voter and stupidity, but is their evidence of an inverse correlation between inane sanctimony and the mean of the remaining ALP supporter’s IQ as exemplified by CHRISTOPHER DUNNE?

    Or is smugness a passive variable correlated to CHRISTOPHER DUNNE and not low IQ per se?


    Poss, is there a direct negative correlation between the primary vote for the Coalition and IQ?

    Why have we become so stupid, insular, ignorant and fearful? Please tell me this isn’t so.


  19. mattsui

    Any stats on the Mayan Calander, Possum?
    Could be Labor’s best hope.
    2012 global apocalypse. Or 2013 electoral apocalypse with post-apocalyptic zombie government.

  20. Possum Comitatus

    Wouldn’t even hazard a guess SD – especially when the last Senate spot in each state and sometimes the final two spots in each state, are decided on preference deal arrangements with pretty minor parties

  21. SD

    Any speculation as to what these numbers might do for the Senate assuming a half senate election? Any chance that the Coalition could scrape a majority with independents, DLP etc?

    I realise there are issues here, not least that some people vote differently in the upper house.

  22. Possum Comitatus

    Kim, there’s not enough data to break down Tassie and the territories in any confident way, so that’s why they generally get left out of the pollster’s breakdowns

  23. Possum Comitatus

    Caf, it’s mathematically possible that WA and Qld would be Laborless if these polling numbers reflected themselves in an election.

    Not likely, actually extremely unlikely because of joint probabilities, but mathematically possible.

  24. Kim Perkins

    Last time I checked the map there were 6 states in Australia. Although the number of House of Representative seats from Tasmania would not make a huge impact on the swing against Labor, it is just plain rude to ignore that state completely. (I live in Victoria by the way)

  25. Possum Comitatus

    Andos – will depend on Lib preferences on one hand, and whether Adam Bandt has built a strong local following on the other.

  26. caf

    So it’s even money that Rudd will be the last ALP man standing in Queensland, and a non-negligable chance that the ALP will have no representation at all in Queensland or WA?

  27. Andos

    Cool, cool, but what about Melbourne? I guess there’s no chance of retaking that particular piece of heartland…

  28. Possum Comitatus

    Andos – it is. I added Grayndler (and Batman – which is another) to the list because they just scraped in to becoming a non major head to head, and the Libs arent keen on preferencing the Greens in those seats at the next election.

  29. JamesK

    Thanks for the detailed analysis Possum, given that it’s not even close.

    However saving the furniture is very very important. I hope some hard heads in Labor are making calculations and formulating a realistic path there.

    Surely Gillard can’t be at the helm? If not who and when?

    The technical term horseshit brought back memories of the famous Peter Cooke & Dudley Moore, who described ‘lobsters up the bum’ as a the scientific term for what was known colloquially as ‘lobsterismus bumakissimus’.

    Is the everyday term for stretching stats to the limit: ‘excrementum equinus’?

  30. spoetmoenkey

    Curious as to whether you’ve had a stab at factoring in Peter Brent’s favoured ‘sophomore swing’ theory.

  31. This little black duck


    Glad you do econometrics and not crystal ball.

  32. feeney


    You’ve done a lot of good work there.

    However, looking towards an election in October 2013, it bears little relevance to possible outcomes then.

  33. Space Kidette


    Great work but it really should have come with a “Bring your tissues” warning.

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