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

Yesterday, the Coalition announced its tough on drugs policy.

Labor announced support for the world game, its commitment to lift school standards, and its plan to reduce violence against women and children.

Morgan: Morgan released a phone poll of 1670 voters on 15-17 November. The sample was weighted to marginal seats, with 1,025 electors in 22 key L-NP marginal seats. (I gather the other 128 seats were estimated with a sample of 645 voters) . The headline prediction was Labor on 55.5 per cent of the two-party preferred vote. The Coalition got 44.5 per cent. As can be seen from the next graph, this series has been pretty much a flat line during the election period. Note that I graphed how voters said they would vote, rather than the TPP figure based on preference flows in 2004, to maintain consistency with earlier Morgan phone polls.

I do not have enough data to confirm a house bias with the Morgan phone poll; nonetheless, it appears to track to the left of ACNielsen and Newspoll (see next graph). House bias effects should be taken into account when using a poll series to estimate the final national TPP outcome.

Other polls: In today’s SMH and Age, we have an ACNielsen poll for the seat of Wentworth. The headline result was 52-48 in Labor’s favour.

The SMH reported a Patterson poll of Eden-Monaro, which had Labor ahead 53 to 47 per cent.

Mumble has the latest demographic breakdown from ACNielsen.

Yesterday, there were no new policies on Labor’s website.

The Coalition had no new policies listed on its website.

Betting market: Being a Sunday, it is time to look at the betting markets (perhaps for the last time). Last Sunday, the average probability of a Coalition win from the five bookmakers I am tracking was 30.6 per cent. This morning it was 20.9 per cent.

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

Galaxy marginal seat poll: Galaxy polled 4000 voters in twenty marginal seats between 11 and 15 November. The Poll Bludger has a graphic of the results here. If you extrapolate the marginal seat results to the state (not exactly kosher) and drop them into Antony’s calculator, it yields 83 seats for Labor. This result is more conservative than yesterday’s Newspoll of marginal seats, which gave us a prediction of 90 seats.

ERMS poll: in today’s Sunday Examiner suggests Labor will pick-up all five Tasmanian seats.

Taverner poll of mortgage holders: The SMH and Age reported on a Taverner poll of mortgage payers which found them split 57-43 in Labor’s favour. Apparently, 34 per cent of households are mortgage payers. According to the papers, this result is a reversal of a similar poll before the 2004 election.

PM Rudd’s first steps: The SMH reported that the first steps of Prime Minister Rudd would be,

1. Ratify the Kyoto Protocol. “We need to make sure we are around the negotiating table immediately … for the next round of commitments on reducing global greenhouse gas emissions.”
2. Start immediately to negotiate with the states on reform of hospital practices. “That is of crucial importance - we’ve got $2.5billion on the table but we’ll need to frame a co-operative agreement around performance measures.”
3. Begin the roll-out of the high-speed broadband network, along with connections to schools. In tandem, open up tenders for the $1 billion school computer program.
4. “Hit the ground running” with the implementation of the $2.5 billion program to upgrade trades training centres in secondary schools. “I went back to C block [the technical faculty] at [his old school] Nambour High the other day - it hadn’t changed since I was there. It was like walking into a museum.”
5. Begin negotiations with the Americans and Iraqis for the staged withdrawal by mid next year of Australian combat troops. “I have been very blunt with President Bush … I have a no-surprises policy when it comes to these things.”

One week from today the nation will elect a new Parliament.

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

Labor announced policies on early childhood, radiotherapy in Lismore, a GP Super Clinic for Wallan, Sisters Of Charity Outreach In Devonport, Forward with Fairness for Australia’s Young Workers, the Central West Queensland Growth Corridor, Northern Territory Roads, NT Remote Airstrips and WA Infrastructure.

Go on, test yourself: with the updated, LDP, 10 question Australian Political Quiz. The Oz Politics test is here. The News Limited test is here.

Newspoll: Today’s Australian reported a Newspoll of 3615 voters in 18 key marginal seats over the period 12-15 November. The headline prediction was 54 to 46 in Labor’s favour. Sol Lebovic’s analysis is worth reading.

Morgan: The latest Morgan poll is out. It has returned from its stratospheric prediction of a fortnight ago — 62 per cent for Labor (judged an anomaly by many) — to 56.5 per cent to 43.5 per cent in Labor’s favour last weekend. Nonetheless, of the most recent projections for the six polling streams, it remains the most favourable for Labor.

If we take the middle four projections, they range from 54 to 56 per cent for Labor, with an implied seats haul in the range from 87 to 96 seats.

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: Possum has built a regression model that predicts Labor will win 55.15 per cent of the national two party preferred vote. According to Antony’s calculator, this translates to 94 seats. This is just a touch up on Possum’s earlier prediction of 54.9 per cent, but it is not as high as Geoff Lambert on 55.5 per cent.

Critics of the model in Possum’s comments suggest it is over parameterised. The model has nine variable terms and 13 input variables. While the model shows an impressive fit and it has accurately predicted Labor’s two-party preferred vote over the past three elections to 0.1 per cent, the critics believe it is an example of line-fitting rather than a predictive model. One wag gave a paraphrase of John von Neumann’s, “With four parameters I can fit an elephant, and with five I can make him wiggle his trunk”.

Worth a read: Adam Carr’s twelve seats that will decide the election.

What the … On ebay there is a John Howard pinata. The current bid is $405. Suggested use is for an election night party.

Another trend. This time I have averaged the latest ACNielsen, Galaxy and Newspoll phone polls each week. I have then applied a 13 term Henderson filter to get rid of the lumps and bumps in the series.

If we project the phone poll trend out until the election date, it looks like a national two party preferred vote of (around) 54 per cent for Labor. Drop that guesstimate into Antony’s calculator, and we get a prediction of 87 seats for Labor.