Like Nate Silver, only less accurate
The latest estimate of voting intention has the ALP/LNP two-party preferred at 48.9/51.1. That's based on primary votes estimated at: LNP 41.6, ALP 33.7, Greens 11, Palmer United 0.1, Independent/Other 13.1. See the Trends section for more details.
The model figures a 98% probability of an LNP win, a 1% chance of a hung parliament, and a 1% chance of an ALP majority. See the House of Reps section below for details on individual seats.
These trendlines are fitted using a linear state space model. The underlying state variables are the primary votes for each party in each State and Territory. The model fits a simple local level model to each component, but it uses a factor model for the covariance of each week's innovations. Estimates of national votes and TPPs are made using population weights and last election's state-by-state preference flows.
Each polling source has a fixed house effect in the form of a Gaussian error distribution. Elections are assumed to be perfect observations. I match the timing of each polling sample, so that e.g. Newspoll's quarterly averages are modelled as noisy observations of the underlying data averaged over a quarter.
The complete code and data for the model, and for this website, are available on GitHub.
There's another statistical polling model over at Mark The Ballot, and one under development by Clinton Boys. The Poll Bludger and Dr Kevin Bonham both publish regularly updated polling aggregates which they put together using their own judgement. And Hugh Parsonage has a wonderful visualisation of the Reps over at 150 Hexagons.
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