Friday, October 30, 2015

Betting market update

House Coalition Odds ($) Labor Odds ($) Coalition Win Probability (%)
2015-10-30 Betfair 1.13 6.51 85.209424
2015-10-30 CrownBet 1.13 6.00 84.151473
2015-10-30 Ladbrokes 1.15 5.00 81.300813
2015-10-30 Luxbet 1.13 5.50 82.956259
2015-10-30 Sportsbet 1.15 5.50 82.706767
2015-10-30 TABtouch 1.14 5.50 82.831325
2015-10-30 William Hill 1.13 6.00 84.151473

Tuesday, October 27, 2015

Poll update

Today's Newspoll, published in the Australian, has the Coalition on 52 per cent and Labor on 48 per cent (a two point move to the Coalition on the previous Newspoll). The aggregation is unchanged on 52.8 per cent for the Coalition.

Monday, October 26, 2015

Model updates

I have spent a little time refreshing and updating the statistical models I use on this site. I have also updated the Bayesian Aggregation information page, with the current version of the JAGS model code for each of the four models I run.

What's changed:
  • With all of the models, I have changed the way in which I code a discontinuity associated with a change of leadership. 
  • With the anchored models, I have added a discontinuity for the Gillard to Rudd change of leadership and for the Rudd to Shorten change. 
  • Finally, with the sum-to-zero, primary-vote model I have added a two-party preferred (TPP) estimate based on preference flows in 2010.

The annotated TPP results follow. We will start with the sum-to-zero TPP model. This chart uses the TPP estimates from the polling houses. This is the simplest model, and the one I regularly report.

The next chart is the anchored TPP model. It should be noted that prior to the 2013 election, the pollsters would have made their TPP estimate based on preference flows in 2010. Since the 2013 election, the pollsters would have used preference flows at the 2013 election.

The next charts are derived from the primary vote estimates from the polling houses. The first chart is based on the 2013 preference flows. The second chart is based on the 2010 preference flows. There is a percentage point in the different preference flows.

Year From the Greens (%) From other Parties(%)
2010 21.16 58.26
2013 16.97 53.30

The final chart is derived from the primary votes, anchored to the 2013 election result (using 2013 preference flows).

The four charts based on 2013 preference flows can be seen side-by-side as follows:

As an aside, the two anchored charts suggest that the 2013 change from Gillard to Rudd may have saved Labor up to 3.5 percentage points at the 2013 election. It would have saved quite a bit of the furniture.

Saturday, October 24, 2015


I have not looked at the attitudinal polling for some time. But before we do that, let's catch up on the impact of the latest ReachTEL poll, which came in at 53 to 47 in the Coalition's favour. The aggregation now stands at 52.8 per cent for the Coalition.

As with my other models, I have introduced a discontinuity into the attitudinal polling models I use for data fusion/aggregation. I applied the discontinuity to both the Coalition and Labor series. First, however, let's look at the raw poll results. In these charts, we can see a dramatic change in the Coalition's attitudinal polling, and little change in the Labor polling.

And on to the aggregation.

And placing the results from the two Hierarchical Dirichlet Processes side by side, we get.

All over 80 per cent

Today, each of the seven bookmakers I follow are giving the Coalition in excess of an 80% probability of winning the next election.

House Coalition Odds ($) Labor Odds ($) Coalition Win Probability (%)
2015-10-24 Betfair 1.15 5.94 83.779972
2015-10-24 CrownBet 1.16 5.25 81.903276
2015-10-24 Ladbrokes 1.15 5.00 81.300813
2015-10-24 Luxbet 1.14 5.50 82.831325
2015-10-24 Sportsbet 1.15 5.50 82.706767
2015-10-24 TABtouch 1.14 5.50 82.831325
2015-10-24 William Hill 1.13 6.00 84.151473

Tuesday, October 20, 2015

Yesterday's polls move betting markets

House Coalition Odds ($) Labor Odds ($) Coalition Win Probability (%)
2015-10-20 Betfair 1.18 5.94 83.426966
2015-10-20 CrownBet 1.16 5.25 81.903276
2015-10-20 Ladbrokes 1.20 4.50 78.947368
2015-10-20 Luxbet 1.14 5.00 81.433225
2015-10-20 Sportsbet 1.15 5.50 82.706767
2015-10-20 TABtouch 1.14 5.50 82.831325
2015-10-20 William Hill 1.13 6.00 84.151473

Monday, October 19, 2015

Add Morgan and aggregate ...

This evening we have another poll from Morgan. According to Morgan, if preferences are distributed by the way in which people voted at the 2013 election, the result is 54 to 46 in the Coalition's favour. This is unchanged on the previous fortnightly result.

Turning to the aggregation we are now estimating that the Coalition has 52.6 per cent of the two party preferred (TPP) vote. Intriguingly, the most recent Morgan polls have been more favourable to the Coalition than other pollsters. In the usual run of things, Morgan has a tendency to be more favourable to Labor.

Updating the primary vote aggregation, we have the following.

The primary vote model has the Coalition TPP at 52.8

There is not a lot of difference between the TPP and primary vote model estimates for the Coalition two-party preferred vote share.