Antony Green on why crucial rural NSW election battles have forced him to abandon his Lower House calculator

Updated

The unconventional races being run in rural seats of NSW will not only be the likely deciders of the election, but also spell redundancy for the ABC's usual election calculator.

Key points: The two-party contests in NSW have broken down, producing more complex races particularly in rural seats

Optional preferential voting also leads to a scrambling of the statewide swing

Those unique races will not sit on a uniform pendulum, complicating the analysis on election night

In past elections, the calculator has allowed us to project a prediction of the election outcome — including which seats will fall — when we enter a statewide swing figure.

This election is an entirely different beast.

Twenty years ago, nearly every electorate was a battle of Labor versus the Coalition.

Increasingly, the two-party contest has broken down in NSW, plus we've had two landslide results in a row, and many of the margins in seats look a little odd.

What we're now seeing is contests between Labor and the Greens, Liberals and the Greens, Nationals against independents, even Nationals against the Shooters, Fishers and Farmers Party.

These sort of results simply will not sit on a statewide pendulum.

The only way to overcome the peculiarities would be to make the calculator so complex, its purpose would be defeated.

Some seats, for example, are very marginal and look like they would fall on a statewide swing, but due to the individual contest they may not.

This election will not be decided on an overall state vote — the key will be in seat-by-seat contests.

With seven members on the crossbench, with the potential for even more to be added, it's going to be decided in a bunch of rural seats where the swings will be erratic.

Uniform swings will be more likely in Sydney.

Fine-tuning and a scrambled swing

Further complicating things is the NSW system of optional preferential voting, which scrambles the swing.

Under full preferential voting, every voter must in the end choose between the final two candidates.

Under optional preferential voting, voters can exhaust preferences.

The size of the exhausted vote can amplify or depress the swing compared to the same contest in other seats.

To analyse the results as they come in, we're going to need to look at the individual electorates and the order candidates finish.

For example, Lismore was an extraordinary three-way contest at the 2015 election.

The Nationals led on first preferences, and Labor and the Greens were a close second. But in the end, the Greens finished second.

It may well be at this election, it's Labor against the Nationals.

We will need to look at those specific contests and decide whether candidates are in the right order, in terms of picking a winner.

In the case where the preference count from the NSW Electoral Commission is not the one that appears to be relevant on the night, further estimates and overrides of the results will need to be made.

There will be all sorts of fine-tuning.

By comparison, last November's Victorian election was straightforward to call.

Even though we were yet to receive results in key electorates, it was possible to say the Andrews Government had been re-elected as the overall swing in other electorates was clear and uniform.

In the case of NSW, I'm not convinced there will be any similar swing from other seats that can be applied to making an accurate prediction for the key seats on which we will focus.

It promises to be quite a close contest, and it's also highly likely we won't know who the government is at the end of election night.

Topics: state-elections, elections, states-and-territories, state-parliament, government-and-politics, sydney-2000, nsw

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