Polling update

Two party preferred

Day 32 - 2025 Federal Election

Today we have a new Newspoll (52/48) in Labor's favour. The Bayesian aggregation is unchanged. We are looking at a result much like the previous election if the polls are correct.

Day 30 - 2025 Federal Election

At this point everyone expects Labor to form government following the election. The only question is whether it will be majority or minority government. Based on odds of \$6 (Coalition) and \$1.14 (Labor), the betting market has the probability of a Labor government at 84%. But betting markets must contend with the bookmaker's over-round and the favourite-longshot bias problem. It is reasonable to conclude that most punters think the probability of a Labor win is higher than this.

Day 28 - 2025 Federal Election

The betting market has been remarkably quiet over the past week. What follows is the table of raw odds in dollars for the party to provide the Prime Minister after the next election. I collect this data each day at around 6.30am (local Canberra time). Normally, this close to an election, the odds change every day. 

Day 23 - 2025 Federal Election

I have been refining my code for the individual seats market at Sportsbet.com.au. Before we get to the charts for every seat, let me take you through the changes I have made.

Occasionally, Sportsbet suspends odds for a particular candidate in a seat, and sometimes it even removes an entire seat from the market for a few days. This morning, there were no odds at all for the seat of Franklin in Tasmania. Furthermore, the odds for a candidate in each of the seats of Bendigo (Vic) and Lyons (Tas) were suspended. In each of these cases I use the most recent odds available to calculate seat probabilities. However, to be transparent, when this occurs I add a grey bar to the seat probabilities chart. 

Second, I have changed the way I manage the favourite-longshot bias problem. Before I explain these changes, I need to explain why I do this. Counting favourites from each seat does not give a good picture of the Parliament that is likely to emerge. A better picture of the likely Parliament comes from summing the probabilities. But when I sum the simple probabilities, because of the favourite-longshot bias problem, I do not get enough Labor and Coalition seats (the typical favourites), and I get far too many seats for "any other candidate" (the long shot).  

To address this bias, I treat odds up to \$7.50 normally (ie. for probabilities greater than roughly 15 per cent after the bookmaker's overround). I inflate odds between \$7.50 and \$25 by multiplying them by their square root, this reduces the associated longer shot probability. Finally, I ignore odds over \$25. In many seats, the odds for any other candidate are set at \$26 (fairer odds in many of these cases might approach \$1000). 

With that aside, let's look at the likely Parliament according to the punters.

Day 20 - 2025 Federal Election

Yesterday we had an Essential poll with Labor on 50 per cent 2pp, the Coalition on 45 per cent and 5 per cent undecided (which I make as 52.6 to 47.4 percent with the undecideds distributed). This brings my aggregated poll of pollster 2pp estimates to 51.8 per cent in Labor's favour.

Day 13 - 2025 Federal Election

Today, let's look the complete set of charts from the individual seats market. Overall, we can see another net seat with Labor in the lead. The two seats that were tied yesterday (McEwan and Robertson) have bounced to a Labor lead.

Day 10 - 2025 Federal Election

Twenty-seven days until the election on 3 May. The punters are firming on Labor winning this election.

Day 4 - 2025 Federal Election

Today I am looking at the individual seat betting markets. These markets are tricky to analyse because of the favourite-longshot bias problem. To reduce the impact of this problem, I multiply the odds from each seat by its square root. This has the effect of increasing the odds for longshot outcomes, and thus reducing their probability. To calculate probabilities I take the reciprocal of the odds and then adjust for the bookmaker's overround.

From the individual betting markets we can deduce which parties might win the election. For example, we can count the party that is ahead in each seat. This suggests that the punters think the most likely outcome is one in which no party secures 76 of the 150 seats to form government in their own right.

Day 3 - 2025 Federal Election

Around lunchtime every day I take a snapshot of the odds for the winner of the next Federal Election at sportsbet. I use it as a barometer of public intuition for who might win the next election. At the moment it is very close. Today the win probabilities are effectively 50/50 for both Labor and the Coalition (ignoring the long shot outcome of any other party). 

Friday 28 March - we have an Election date

It has happened. This morning a Federal election was called for Saturday 3 May. The Parliament has been prorogued (a fancy word for closed). The House of Representatives has been dissolved. The Government is now a caretaker government, and (by convention) it only takes major decisions in consultation with the Opposition.

Over the next six weeks I will be blogging most days on electoral and polling matters. Today we will look at the betting market and primary vote polling in the states.

The betting market

The betting market at sportsbet has moved around a bit over the past few days. Around noon today, it gave Labor a 52.6 per cent probability of winning the 2025 election. That is very close to even money, with Labor as the slight favourite going into this race.

Update: opinion polls and betting market

Before I begin, let me tell you a sad story. I went overseas for an extended period, and while I was away, the code I use to daily scrape the SportsBet website stopped working. So, I have a roughly six-week gap in the betting market data. In this time, the odds of a Labor victory have lengthened (with Labor still the favourite to form government after the next election). The betting market has the outcome of the next election pretty close to even money (reflecting the polls below). What has changed is the odds for any other result (which I ignore in the following charts). Those odds have shorted from \$101 to \$81. 

Turning to the opinion polls, we now have an extended period of some four or so months where the projected two-party preferred outcome is very close to 50-50 - the proverbial toss-up. 

At this point, I should note the way in which I model house effects has changed. For those pollsters that have changed their polling methodology (Essential and Resolve), I exclude the polls conducted under the earlier methodology from the requirement that all house effects sum to zero across the pollsters. I also exclude from the sum-to-zero constraint those pollsters that have fewer than five polls published over this period. For the record, the pollsters included in the sum to zero constraint above were: 'Newspoll', 'Resolve Strategic 2', 'Freshwater Strategy', 'Essential 2', 'Roy Morgan', 'YouGov', and 'RedBridge Group'. The estimated house effects for each pollster are as follows (note: these two charts are different ways of reporting exactly the same data).

Turning to the primary votes, some trends are clear. Labor's primary vote is down on the previous election and the Coalition's primary vote is up. The vote share for independents and other parties is down on the previous election. The vote share for the Greens is above where it was at the previous election.  I suspect this reflects some movement from the "Teals" back to the Coalition, and some movement of votes from Labor to the Greens. On these numbers, you would expect whichever major party forms government, they will rely on the support of others for the passage of legislation (yes, the polls suggest a hung parliament).

And for completeness, the attitudinal polling follows.

As usual, if you want to see how the charts were made: click here.

The data for these charts was sourced from Wikipedia.

Betting markets

I have started tracking the betting market at sportsbet.com.au for the next Australian Federal Election. The specific question I am tracking is the party which will supply the Prime Minister following the next election. I plain to capture a snapshot of the relevant odds daily, sometime around midday. I will not be reporting on the "Any other party" odds, as I consider the results to be skewed by the long-shot bias.

As I have only been tracking this for a day, the charts at this stage are not very interesting. 

Nonetheless, I was a little surprised at the 60/40 probabilities. My prior, before looking at the odds, was that it is very unusual for a first term government to lose their first election as a government. 

Movements at sportsbet

Yesterday's Newspoll has resulted in some movement on the betting markets. Note: typically I collect these these odds around lunch time. Also note that I have been collecting the "type of parliament" odds for a longer period than the election winner odds.

The individual seat odds follow (in reverse alphabetical order). The close seats, according to the punters, are: Flinders (VIC), Braddon (TAS), Flynn (QLD), Deakin (VIC), Gilmore (NSW), Casey (VIC), Robertson (NSW), Longman (QLD), La Trobe (VIC), Lindsay (NSW), Boothby (SA), Reid (NSW), Hunter (NSW), Bass (TAS), Hasluck (WA), and Dobell (NSW)

And if people are interested, this is the current distribution of bookmaker overrounds across the 151 seats.