Possums Pollytics

Politics, elections and piffle plinking

Pollytrack, Week 25

Posted by Possum Comitatus on May 20, 2008

In an act of fortuitous timing coinciding with the first anniversary of this blog, Nielsen emerges from polling exile after their less than spiffy performance in their final poll estimate of the last election campaign.

Now having three pollsters to play with – Newspoll, Morgan Phone Poll (I chose to exclude Morgan face to face polls as they behave quite differently to the phone polls of the three pollsters) and now Nielsen, we can construct a rolling average of the three pollsters weighted by sample size to give us what should be the most accurate estimate of Australian federal voting intention.

The Pollytrack series is born.

The way it works is simple, each observation in the Pollytrack series will consist of the average of the most current polls from each of the three pollsters, weighted by sample size. So, for instance, as a new Newspoll gets released, it will replace the previous Newspoll in the three pollster weighted average.

The larger the sample size that a given poll has relative to the other polls that make up Pollytrack, the greater the influence that poll with have on the actual Pollytrack number.

So for the first Pollytrack observation, which is Week 25 of the governments’ term, the three polls are Morgan Phone with a sample size of 618, Newspoll with a sample size of 1141 and Nielsen with a sample size of 1400.

Crunching the numbers gives us a weighted average of primary votes being 46.5 to the ALP and 37.4 to the Coalition with a two party preferred weighted average of 57.2% to the ALP and 42.8% for the Coalition off a broad supersample of 3159.

At the end of each week, Pollytrack will be updated to accommodate whatever new polls get released. As time goes on, we’ll end up with a charted weekly series which I’ll stick up the top under a link called Pollytrack, as well as place the current Pollytrack estimate in the right sidebar at the top. That sidebar number should be updated on the day a new poll comes out (where possible), so if the situation arises where there are a few polls released during a given week, that number in the sidebar will change as each poll comes out. The number at the end of the week is the one we’ll use as our permanent Pollytrack value.

UPDATE:

People have asked what the MoE on this thing is – that depends on the sample sizes of the three pollsters, but will nearly always be between about 1.6% and 2%.

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6 Responses to “Pollytrack, Week 25”

  1. Cat said

    Can we at least refer to it as Possum Pollytic’s PollyTrack to be consistent.
    Would it perhaps be possible (for as long as relevant -or June 29th which ever comes first) to have a Nightwatchman vs Aquaman scorecard to keep an eye on the PPP’s impact on the Liberal leadership melange (or vice-versa)?😉

  2. Don said

    Thanks a lot Poss. PPP will be a really good measure of what is going on for us political junkies.

  3. Pollfoolery said

    Thanks a mill! Just wondering whether you will give us the joy of different weightings as far as the length of time over which the rolling average us taken? And even an exponentially weighted moving average?

  4. Possum Comitatus said

    Pollfoolery – that’s a grand idea. I might play around with a couple of different time weighting techniques and after a few months compare the differences between the current Pollytrack methodology and the time weighted varieties. Then we can all bang our heads together and figure out which one works best.

    Ta!

  5. […] are continuing to improve their coverage of the numbers game. Yesterday, Possum unveiled the “Pollytrack“, a new blog feature which he explains in his post: Now having three pollsters to play with – […]

  6. Pollfoolery said

    Yay for possum!

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