Oz Politics Blog

The latest Morgan is out. While it was in Labor landslide territory, it was the most favourable poll for the Coalition this month. With a sample size of 1274, it was also around 400 to 500 people fewer than I was expecting.

Three of the last four Morgan polls have been close to 55 for Labor and 45 for the Coalition. Newspoll was in much the same space over the same period. The last ACNielsen was also there. While the most recent Galaxy was more favourable for Labor, the Galaxy poll before that was 54/46 in Labor’s favour. My suspicion is that the underlying trend is has been stagnant around 55 to 45 for the past couple of months. According to the election calculator, 55 per cent for Labor would see it win 94 seats.

That completes the polling for August. We seem to have a hiccup to the trend that emerged between March and July. The Coalition is around 1.5 points off where they would want to be at the moment. It will be interesting to see whether September sees a return to the March-July trend or a plateauing.

The usual opinion poll graphs are here. You may need to hit the refresh or reload button on your browser to see the latest graphs.

The usual opinion poll graphs are here. You may need to hit the refresh or reload button on your browser to see the latest graphs.

Regular visitors to Ozpolitics.info will know that I am more interested in the data trends over the medium term than the vagaries of poll-on-poll movements. One of the techniques I use to discern the polling trend is a monthly weighted aggregation. I take all of the polls for a month — Morgan face-to-face, Newspoll, ACNielsen and Galaxy — and recombine them into a single poll result for the month.

From March through July, a clear trend was emerging. That trend, if it continued, would have seen the Coalition in a winning position by mid December 2007.

This month’s aggregation is almost complete. It is only missing the last Morgan poll for the month.

The news? Well it looks like the trend back to the Coalition may have encountered an obstacle. Yes, it may simply be a perturbation in the data. But it is more likely to be something real.

My apologies that the website languished for a couple of days while I was away from Canberra. I am back now!

The average probability of a Coalition win at the 2007 Election from the five bookmakers I have been tracking is 37.7 per cent.

The other graphs are here. You may need to hit the refresh or reload button on your browser to see the latest graphs.

If you don’t want to risk any of your well earned, you can place a tip on the 2007 election here

I have been meaning to look at George Megalogenis‘ data tables for some time. Rather than use the data to predict what might happen this year, I thought I would look at the extent to which electorate income explained the 2004 election outcome.

First, however, a couple of box-plots to get a feel for the data.

And now let’s look at the graph that surpised me. The next scatter-plot suggests absolutely no relationship between the median income wihtin in a seat and the Coalition’s two-party preferred vote from that seat. Just look at the R2. It is almost zero.

Why is it so? Well it appears that moderate correlations exist within inner metropolitan, outer metropolitan and provincial seats. That trend suggests that seats with a higher median income are more likely to favour the Coalition. When you get rural seats, many have very low median incomes, but almost all favour the Coalition.

Update: Andrew Leigh sent the following missive …

Dear Bryan,

I noticed your post yesterday on electorate income and voting. As you know, I’m a great fan of yours, and link to you regularly (it should be more often, in fact). However, I do think you’re making a bad mistake in ignoring the ecological fallacy here. The best evidence of this is the research by Glaeser & Sacerdote that finds that income is positively correlated with voting Republican on an individual level, but negatively correlated with Republican voting across US states (http://andrewleigh.com/?p=1419).

Given that we have very good information about the individual-level relationship between income and voting in Australia (eg. my own work, or that of Goot & Watson in a recent AJPS), I’m puzzled as to what you think we can learn from the aggregate-level stuff. You, of course, know all about the ecological fallacy, but I’m worried that some of your readers may be misled.

Politically, this plays into the muddle-headed argument that the Libs make from time to time: that they’re just as much the party of the poor as the ALP. That’s simply a lie.

Cheers,

Andrew.