As we all get reacquainted with the madness that is the first week of the new political season, the time is ripe to do a bit of a comprehensive rundown about the actual state of play of our political polling. We’ll start off looking at the trends and finish with an election simulation for the December quarter.
First up, the two-party preferred trend might surprise a few folks that take their media polling commentary too seriously — it reminds me of a line from Chicken Run: “The polling flashed before my eyes, and it was really boring.”
Over the three months from mid-November, nothing has changed at all in the two-party preferred status — zip, zilch, nadda. Federal politics has been glued to a 54/46 split for nearly 90 days straight.
The primary votes however are a little more interesting, with some compositional change occurring underneath that rather dull looking straight line …
While the Labor primary continues to recover from its July tanking — albeit at a pace not dissimilar to continental drift over the last few months — Coalition primary support fell to 46% at the end of last year, before bouncing back slightly post-Christmas. It’s interesting to ponder whether that is an effective Coalition vote floor under the prevailing dynamics.
Meanwhile, the Greens continued their year-long voyage of exploring political life between 11% and 12% public support and the broad “others” — apart from pollsters having considerable variation in their vote estimates for this ragtag group — appeared to show a continuation of the slow fade that started after their June 2011 highs.
As of last weekend, the actual point estimates of the trends and the changes from the last election look like this:
The government has a 5.4% swing away from them on the primary vote, washing out to a slightly smaller 4.3% swing away from them on the two-party preferred. The Coalition has picked up 3.1 points on their primary while the Greens have lost 0.4 points. The broad “others” have picked up 2.7 since the 2010 election.
Moving on now to December quarter’s election simulation. For those not familiar with it, we grab three months worth of polling from the major pollsters and a few bits of unpublished stuff (usually giving us a pooled sample of around the 13-15,000 mark), break it down by geography (by state first and foremost, but also by region when possible), turn the derived swings from those polling results into probability distributions for each seat (taking account of their sub-state geography) — then test those swings against the current seat margins about a million times with a monte carlo simulation and aggregate the results. We end up with a simulated election that shows us how many seats would have changed were an election held during that period and the results of the election closely resembled the polling.