I’ve done 2 simulations of tomorrow's (May 3) Australian federal election using the seat by seat betting odds from Sportsbet, TAB and Ladbrokes.
The simulation dates were 23 April and today, May 2.
The exact method of simulating the probability
distribution of possible election results is described in detail in my post simulating the 2013 federal
election.
In brief, any seat for which all 3
betting agencies have one candidate paying less than 1.10 is deemed safe and
allocated to that candidate. As of today, there were 74 of these: 39 Labor, 33 Coalition and 2 independents: long time MPs Bob Katter in Kennedy (Far North QLD) and Andrew Wilkie in Clark (Hobart). There were 68 last week.
That's a historically low proportion of safe seats. It's driven by the large number of independents / Teals.
For the remainder of contested seats, I derive the
probability of winning in each seat from an average of the implied
probabilities from the 3 sets of bookmaker odds. I used 10 simulations of 100,000
runs each. In each run, a winner for each contested seat is decided by a correlated, random
draw of each candidate, with the probabilities derived from the odds for that
seat.
Each set of 100,000 runs gives an
estimated probability distribution for the number of seats won by each party
(and independents). The 10 sets of runs are to determine the stability of the
distribution estimates. Runs are done across a range of correlation parameters, to simulate swings in general electoral mood.
In the current parliament, there are 151
federal seats, so 76 required to form a majority government. The Labor (ALP) government currently has 77, the Coalition
(LNP) 53, with 19 on the cross benches, plus 2 vacancies. The vacant seats are Hinkler, centred on Bundaberg / Hervey Bay in QLD and Maribyrnong in northern Melbourne.
Hinker is vacant because MP Keith Pitt (LNP) resigned to become ambassador to The Vatican. One less devout Catholic in parliament is a small improvement. Maribyrnong is vacant because MP Bill Shorten is retiring to a Vice-Chancellorship at the University of Canberra, where I'm sure his ego and penchant for slippery politics will benefit students and staff alike.
Interestingly, an electoral
redistribution last year reduces the post-election parliament to 150 seats, still
requiring 76 to form a majority government. NSW and Victoria have each lost 1 seat and WA gained one. That's a surprising outcome, since Victoria now loses the seat it gained in the 2018 redistribution, returning to 37.
The first simulation on April 23 gave a probability of 43% for an ALP majority, 55.5% for a hung parliament and 1.5% for an LNP majority. The most likely distribution of seats was 73 - 74 ALP, 62 - 63 LNP and 14 on the cross benches: 11 independents and 3 greens. That implies an 88% probability of a Labor government, either majority or minority.
With likely conservative independents in Calare and Cowper, plus independents in conservative electorates such as Indi, Monash, McPherson and possibly Bradfield, I set the bar at 71 seats for the LNP to form a minority government. That's because, conditional on the LNP gaining 71 seats, the mostly likely result is 68 for Labor, 9 independents and 2 Greens. That should be sufficient buffer over Labor to gain the support of 5 independents.
Mackellar and Warringah on Sydney's Northern Beaches are also conservative electorates. However Zali Steggall (Warringah) is essentially a Labor candidate and Sophie Scamps (Mackellar) has such a bee in her bonnet about failing to gain endorsement as the Liberal candidate for the 2022 election, she's just as likely to ignore her constituents and side with a Labor minority government. Who knows what Allegra Spender in Wentworth would do, let alone Bob Katter?
The simulation on election eve May 2 showed the Coalition's chances of even forming a minority government have significantly decreased.
There were 39 safe ALP seats, 33 for the LNP and 2 independents: Bob Katter in Kennedy (Far North QLD) and Andrew Wilkie in Clark (Hobart).
The additional 76 contested seats were
simulated and returned the most likely scenario of 77 or 78 seats for Labor, 58
or 59 for the Coalition and 14 on the crossbenches: 11 independents and 3 greens. I'm counting Rebekha Sharkie (Centre Alliance) in Mayo (SA) as independent.
Overall, the simulation gave a 59% probability of a majority Labor government and a 41% chance of a hung parliament, so in the course of little over a week, Labor has firmed from a likely minority government to a likely majority.
The LNP's chances of even getting to 71 seats and forming a minority government have slid to about 3 or 4%. The chances of them governing outright are negligible.
That's because the Coalition's recent campaign has been disastrous. Dutton's selling point is a strong Conservative who knows what he believes and you'll get what you see. Yet he has stumbled and vacillated over policies. Then he became desperate and tried throwing money at voters, losing credibility as a careful financial manager in an economy with far too much debt as it is.
His nuclear policy is too expensive and will take too long to build versus alternatives like battery farms. Although, if we're buying nuclear submarines, we should be able to produce our own fuel for them. It may be prudent to build at least a couple of reactors. But no-one in the Coalition has effectively articulated that idea.
We've seen very little from his potential front bench. People who might be naturally wary of the agenda of the ALP left have lost confidence in the Coalition as a viable alternative: competent and ready to govern.
This has certainly been reflected in movements in the betting
odds in many seats.
Interestingly, the number on the cross benches is likely to decrease from 19 to about 14. Modelling suggests all of those seats will be picked up by the LNP. Labor will likely be in close to the same position they are now.
But increasing LNP representation to 58 or 59 from the current 53 will be nothing for Dutton and the Coalition to feel good about, if they even manage it. That's a poor result against an unpopular government full of very ordinary performers and a testament to the current lack of talent in the LNP ranks.
