With the Newspoll quarterly release this week, we now have enough data to aggregate the pollsters together, break the aggregated sample down into state based components and run our first election simulation for 2011.

Before we start though, it’s worth running though an updated Pollytrend to show how the polls have moved over the January to March period.

As we can see, things were pretty calm over the first 6 to 7 weeks of the year in terms of the two party preferred national results. Over the last 5 weeks however, a fairly large chunk of us went a bit berko over the carbon tax, boat people and other topical favourites of the hyperventilating classes.

What this means in practical terms is that the Labor party are today sitting a little above their aggregate support level of the last 3 months that we use for the simulations – by about half a percentage point of two party preferred thereabouts. Not a massive difference, but worth noting since someone would have in comments anyway.

At the state level breakdown, this is what the last 3 months of aggregated polling suggested in terms of the swings operating since the last election.

The government has boosted its stocks in WA, but have lost ground to the Coalition in NSW, Vic and SA – where most of that lost ground is occurring in the capital cities.

As always, we’re running our quasi-dependency Monte Carlo based simulation method which treats individual seat results as neither dependent nor independent events, imitating the real world effects we see operating in elections  where seats “move together” at the state level of aggregation. After 20,000 iterations, the simulation stabilised giving us the following results in terms of the number of seats the ALP would have been likely to win (click to expand).

69 seats was the most likely result, with the implied probabilities of achieving higher numbers of seats dropping off pretty quickly. A more practical way of looking at the results is to change them into the implied probability of the ALP winning *at least* X number of seats:

Zooming in on the critical area around 69 seats gives us:

So we have a 63% implied probability of the government winning at least 68 seats, dropping down to a 54% implied probability of the government winning at least 69 seats (the most likely outcome), before dropping again down to a  44% implied probability of the government winning at least 70 seats were an election held over the last 3 months and the election result was similar to the polls.

In terms of the implied probability of Labor winning government outright or near outright – there was a lowly 8.7% likelihood of the government getting 75 seats and only a 5.4% implied probability of the government winning 76 seats at an election.

Based on the polling of the last 3 months, the government would most likely have lost 3 seats and Tony Abbott would have become Prime Minister.

The sidebar has been updated with the latest Pollytrend results as well as this simulation.

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Peter Fray
Peter Fray
Editor-in-chief of Crikey
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