Liberals need perfect storm to lose Higgins Friday, December 4, 2009

Here's a super quick one, mostly to test the normal distribution features of apolllo (my advanced simulation software).

What are the chances of defeat for the Liberals in Higgins tomorrow?

Taking the 10 declared candidates for tomorrow's lower house (hey, I thought this was for SENATE speculation) by-election in Higgins to replace noted high taxing former treasurer Peter Costello, and the How-To-Vote cards available online (Liberals, Democrats, Greens, One Nation, Liberal Democrat Party and the Australian Sex Party), and reverse engineering the others, I created a scenario in my election simulator, Cassandra.

Then I started adjusting the Liberal vote down and the Green vote up until the Green candidate started winning. I used the Green candidate because the 2007 election indicates that party has the best chance of defeating the incumbent party in the absence of a Labor candidate.

Once I had a bare minimum scenario for an upset, I put it through my program apollo, which allows me to run thousands of simulations using slightly different parameters.

In this case, I ran 20,000 simulations using a normal variate distribution on the votes and a margin of error of 4%. It's all idle speculation dearies.



Fig 1 - Margin of Error 4% on my prediction

What goes Figure 1 show? Well, with a base vote of 38% for the Greens and 46% for the Liberals, the Greens win the election in 8% of 20,000 simulations. The Liberals win in 92% of simulations.

Bumping up the margin of error to 10% we get a slightly different graph:


Fig 2: Margin of error 10%

The Liberals win in 75% of simulations.

So even with a low primary vote of 46% for the Liberals and an exceptionally high vote of 38% for their nearest competitor the Greens, we can see pretty quickly in the above graphs how unlikely is a Greens victory.



Bumping up the Greens' primary vote to 40% and dropping the Liberals to 45% tips the simulations solidly in the Greens' favour, reflecting favourable preference deals. But a Liberal vote of 45% in Higgins would be such an earthquake that the Liberals would lurch straight back into crisis. We can only hope.

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