Oz Politics Blog

Yesterday, Labor announced policies on or funding for cyber-safety, mentors for students, defence and IT projects in Northern Adelaide, congestion on Sydney rail, the botanical gardens in Canberra and a Wimmera-Mallee water pipeline.

The Coalition announced its forestry policy.

Newspoll: Today’s Australian had the latest Newspoll. The headline prediction was 54 to 46 for Labor.

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.

Predictions: Simon Jackman predicted Labor would win 54 per cent of the two party preferred vote (with a 95 per cent confidence interval that the final result would be between 52 and 56 per cent. Drop that figure into Antony’s calculator, and it gives a prediction of 87 seats.

Simon’s prediction aligns with my perceptions of how the polls are trending. However, I discovered I am uncomfortable with the way both Antony’s calculator and mine translated two party preferred predictions into seat counts. We both used a simple, binary cut-off method. This can lead to very lumpy results. For example, with both of our online calculators 54.0 per cent for Labor yields 87 seats; but 54.1 per cent yields 90 seats.

A solution to my problem with the lumpiness of the online calculators came from a conversation I had with Antony Green a few weeks ago. Antony explained how the ABC does its election night seat prediction by summing the probability of the parties winning each seat (based on a booth by booth comparison function within seats). I decided to test a similar approach to converting TPP results to seat outcomes by summing probabilities. This approach allows a better recognition that individual seat swings are typically normally distributed around the national (or state based) uniform swing.

Rather than recording a seat as a win (1) or a loss (0), I have applied a cumulative probability function with a standard deviation of 2.3 percentage points. If a seat is sitting on the same margin as the predicted swing, it would have a 50 per cent chance of being won by both parties. If the seat was on a margin 4.6 percentage points below the predicted swing to Labor (ie. two standard deviations) it is 96 per cent likely to go to Labor. If a seat is sitting on a margin two standard deviations above the predicted swing to Labor, it has a 4 per cent chance of being won by Labor.

The results of my test of this concept follow. While Antony’s and my online calculators suggested 87 seats, the probability model suggested 88 seats. (There were also some minor differences between the probability model below, which is accurate to one decimal place, and the online calculators that round to two decimal places. In the binary cut-off model below, I have scored a seat as 0.5 if the swing equaled the margin).

But this leaves me with a dilemma. How do I compare election predictions from those commentators who have provided a prediction in terms of a TPP percentage, and those who have made a prediction on the basis of seat counts. My resolution is to covert the TPP predictions to a simple cut-off prediction from Antony’s calculator, and the probability prediction from my spreadsheet. The results follow.

As an aside, an advantage of a probability based model like the one above is that it allows for a direct comparison of seat win probabilities with the betting market. This allows for a better identification of under-priced and over-priced odds. In this context, having a view on the state based swings is also useful to model.

Next election, I wiill work on a probability based seat calculator, rather than the simple binary cut-off model I did for this election.

Update: Antony Green sent me the following email.

Just to let you know, my prototype calculator that was based on probability calculations produced 88 seats, not the 87 produced by the web version on the ABC site. That matches your table of calculations.

I get a +/- 5 seats on this prediction. The reason we didn’t do the probabilities on the web calculator was because of the extra calculation load imposed by the probability calculation, plus the fact that the +/- error was roughly the same whatever result came out of the calculator. And the only difference in Labor seats won tended to come out at 1 or 2 seats.

And Will From Kooyong sent me this.

I read your blog this morning, and it’s quite funny how yesterday I had decided to create a Monte Carlo simulator to predict seats that the likelihood of a win for the ALP. I used a std of of 3.05 (based on last election’s swings), and I tried your std of 2.3. The results I got were very close including the probability of seats changing hands.

Here is a post I put on Poll Bludger late last night when I ran it for a 54% TPP for the ALP, 3.05 for the std and 100,000 simulations. (I ran it for a 1m and it was very much the same).

http://www.pollbludger.com/?p=729&cp=3#comment-88637

Newspoll: Dennis in the Australian reported the latest Newspoll. The headline prediction was a national two party vote share for Labor of 55 per cent, compared with 45 percent for the Coalition. According to Antony’s calculator, if this result was replicated at the 2007 election, Labor would win around 94 of the 150 seats in the House of Representatives.

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.

Other polls: The Daily Telegraph reported on a poll study (N=200) which had Howard and McKew neck-and neck.

The Townsville Bulletin reported a poll (N=209) which would see Labor win the seat of Herbert with 53 per cent of the two-party preferred vote; a nine per cent swing.

Yesterday, the Coalition had no new policies listed on its website.

Labor had no new policies listed on its website.

This week, The Coalition campaign launch is in Brisbane today. Labor’s campaign launch will also be in Brisbane, on Wednesday. (The Age)

Newspoll: Today’s Australian contained the best Newspoll for the Coalition all year; 53 to 47 in Labor’s favour on a two-party preferred basis.

In trend terms, all of the pollsters are showing a narrowing of the gap between the parties on a two party preferred basis. With the exception of Morgan, the latest poll results are beginning to suggest a comfortable win for Labor, rather than the landslide win the polls were suggesting six or seven months ago. If the polls continue to narrow at the current rate over the remaining three weeks of the campaign, it could be a close election.

Applying the current trends to Antony Green’s election calculator we get the following seat projections for the House of Representatives.

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.

Yesterday, The Coalition released a policy statement on roads funding in South Australia.

Labor released policies on Indigenous education in the NT, men’s health, NT Health, a GP Super Clinic For The North Central Coast, economic development in Indigenous communities, scallop fishermen, Gippsland Lakes Communities, and the Ipswich Growth Corridor.

Newspoll: The latest Newspoll was published in today’s Australian. The headline two-party preferred result from the sample of more than 1700 voters was the best for John Howard since mid-February: 54 to 46 in Labor’s favour.

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.

Yesterday, Labor made policy statements on the Great Barrier Reef, women’s health and the Great Eastern Highway in WA.

The Coalition made a statement on technical colleges.

Betting markets: The latest media statement from Sportingbet Australia included the following, “John Howard will begin this week with the seemingly impossible job of coming from behind at odds $3.25 in the betting market to win. Sportingbet Australia CEO, Michael Sullivan today revealed that such a feat had not been achieved previously to his knowledge in the history of election betting. ‘I’ve been running betting markets on elections for twenty years now and I’ve never seen either Party come from this far behind in the odds to win,’ said Sportingbet CEO Michael Sullivan.”

Before reviewing yesterday’s happenings, let’s start with the latest Newspoll from the weekend, based on an expanded survey of more than 1700 voters. Newspoll’s headline prediction was a national two-party preferred vote share of 58 per cent for Labor and 42 per cent for the Coalition. That is a two point improvement for Labor on the previous Newspoll, and a two point decline for the Coalition. The Australian’s Dennis Shanahan is here. (You may need to hit the refresh or reload button on your browser to see the latest graph).

Last week the movement to the Coalition in the ACNielsen and Galaxy polls gave rise to the possibility of a Coalition recovery. For many, I suspect today’s poll would cast some doubt on that prospect. Simon Jackman argued that the difference between the earlier polls and today’s Newspoll was Labor’s matching of the Coalition tax plan.

Bottom line: public opinion on Friday-Sunday (when both tax proposals were before the voters), was more friendly to Labor than it was Monday-Wednesday, when the Coalition’s tax announcement had yet to draw a response from Labor. Having scored the week as a win for the Coalition, I’d have to revise that to a draw in light of the Newspoll numbers. And the kicker is that the Newspoll numbers are pre-debate.

Yesterday, saw three new policies on the Coalition’s website: from Sunday was the Climate Change fund, and announced yesterday were a dental workforce for Northern Australia and better cancer care and support for women.

Over at the Labor website, we have the first two official election policies: a work and family policy document and an affordable childcare policy document.

If you don’t have high speed broadband, you may not be able to read the Coalition’s policy documents from home as three of the five policy statements on its website are some 2.5 megabytes in length. At around 362 and 154 kilobytes in length, Labor’s policy documents are around 10 percent the size of the Coalition’s policy documents. I am intrigued by the Coalition’s strategy of having high quality cover page images in their policy documents but at the cost of making the documents less accessible over the Internet to mum and dad voters. The Coalition took a similar approach to the size of electronic policy documents in the 2004 election.

Andrew Norton noted that the worm was stratospheric when Kevin Rudd claimed that people are feeling worse off due to rising costs. Norton explored whether this is a case of the objective statistics not capturing the subjective experience of the Australian electorate. He concluded, “Whatever Kevin Rudd says, whatever the worm says, these are good times. The typical family may want more, but they are not worse off than before.” Norton’s discussion reminded me of the effectiveness with which John Howard used the phase “five minutes of economic sunshine” to combat Keating in the 1996 election. It also reminded me of the maxim: perception is reality.