Simulating the Finalists for 2015 After Round 19

Fremantle clearly increased its chances of taking out the Minor Premiership this last weekend in defeating the Saints while the Eagles went down to the Hawks. That said, the Dockers still face the Eagles as the home team at Subiaco, as well as the Roos and the Power as the away team, so they're not yet certainties, some in the popular press' views notwithstanding.

According to the latest simulations, which are based on the team-versus-team probabilities shown at right, Freo are now about 77% chances for the Minor Premiership, with the Hawks about 12% chances, and the Eagles 11% chances.

No doubt some would quibble about a few of the entries in that matrix, but they flow directly from the current ChiPS Team Ratings, and the assumptions the ChiPS System has been making all season about each team's Home Ground Advantage (HGA) at each venue and the benefits of playing an out-of-state team at home. And, it's fair to say, the predictors derived from the ChiPS System, C_Marg and C_Prob, have been having a stellar year in predicting results and assessing probabilities, as you can see from the latest Tipster Dashboard

That said, I do think there's room to improve the HGA and Interstate adjustment factors next season by allowing them to adjust dynamically during the course of a season, rather than stay static throughout the entire season as they do now. A statistical modeller's job is never done ...

Anyway, those assessments render the latest TAB Dockers' and Eagles' Minor Premiership prices slightly unprofitable - suggesting we're not all that far away from the TAB bookmaker's opinions about these two teams - but also imply that the Hawks at $10 for the Minor Premiership might still represent a little value.

The simulations also have the Dogs and the Tigers finishing in the Top 4 often enough to make their $4 and $8 prices seem value in the Top 4 market, the Dogs now assessed as about 29% chances for the Top 4 and the Tigers 15% chances.

No team now offers significant value in the Top 8 market however, the Crows showing a small positive expectation, though one too small to make wagering advisable (if it ever is). The Miss the Top 8 market has now disappeared from the TAB, so no comments about value opportunities in that market are possible.

There's also still no market on the TAB for the Spoon though, should there have been one, the Lions would have firmed significantly after last weekend. The simulations now have them as about 81% chances for the Spoon, up from just under 60% at the end of the previous round. The Blues are now about 4/1 chances, and the Suns about 100/1 chances.


Time for the MoS Dinosaur charts, which this week show yet further consolidation in teams' possible futures, with only a handful still capable of finishing in any more than three ladder positions with non-trivial probabilities.

Adelaide, Geelong, GWS, the Kangaroos, Richmond, and the Western Bulldogs remain conspicuous by the range of plausible possible outcomes that await them, dependent on their own and their opponents' abilities over the remainder of the home-and-away season.

The latest heat map shows even more clearly the narrowing of most teams' most-likely finishes, and the relative uncertainty surrounding positions 5 through 10.

TOP 2s, 4s and 8s

The latest simulations have a Dockers/Hawks 1-2 finish as a little over a 50:50 proposition, and a Dockers/Eagles finish as about a 3/1 shot.  After that, a Hawks/Dockers finish arises about 11% of the time, and an Eagles/Hawks finish about 8% of the time. 

It's not until we reach the 7th most-likely pairing that we find a Swan in the mix, that pairing having Freo in 1st and the Swans in 2nd, but appearing in less the 0.1% of the replicates.

Fairly obviously then it's almost certainly going to be some two of Fremantle, Hawthorn and West Coast finishing as Minor Premiers and Runners-Up.

Amongst the most common Top 4s emerging from the simulations, eight of the top 10 see Fremantle finishing first, and one of the remaining two have the Dockers finishing second.

Most common of all is a Freo/Hawks/Dogs/Swans finish, which arose in about 19% of all replicates, which is about 50% more often than a Freo/Eagles/Hawks/Swans finish, or a Freo/Hawks/Eagles/Dogs finish.

No quartet after those appeared in more than 7% of all simulation replicates.

Turning next to Top 8s, and again acknowledging that none of the sets shown here carry probabilities above 1%, we find that the single most-common Top 8 is Freo/Hawks/Eagles/Swans/Dogs/Tigers/Roos/Crows. That combination cropped up in about 0.9% of the simulation replicates.

Further down the list of most-common Finalists, the Cats make an appearance, they finishing 8th in the 7th-most common Top 8, nudging out the Crows, who the Cats play in Round 23.

It's instructive, I think to understand that no combination of teams for the Finals yet carries a probability that makes it more than a 100/1 prospect.


As is now custom, we'll first look at how one Finals aspirant's fate is dependent on another's, by reviewing a subset of the simulation replicates to estimate how likely it is that Team A makes the Finals conditional on Team B making or missing the Finals.

We see this week that Adelaide's fate appears very tied to Geelong's, the difference between the Crows' chances of making the 8 if the Cats do or don't now 44% points. Similarly, Geelong's chances seem most tied to Adelaide's, their estimated probability of playing in September moving by 35% points dependent of whether the Crows do or don't make the 8.

Collingwood's hopes of making the Finals, slim as they are, seem most tied to Richmond's, GWS' to Adelaide's, the Kangaroos' to Port Adelaide's, and Richmond's to Collingwood's. The Western Bulldogs' chances are largely impervious to the fates of the other Finals aspirants.


Lastly, we'll assess the importance of each of the 36 remaining games on the inclusion or exclusion of teams from the Final 8. As we have for the past few weeks, we'll provide both a raw and a weighted view of the importance of each remaining game, though we'll restrict our commentary to the latter view for reasons explained in that earlier blog post (which essentially amounted to a claim that they provided a more useful assessment).

Using that weighted view we find that the most important remaining contest is the Cats v Pies game in Round 22, which is slightly more important than the the Saints v Cats game in Round 21, and the Cats v Crows game in Round 23. Other games in the Top half-dozen are this week's Dons v Crows matchup, the Round 22 Crows v Eagles matchup, and next week's Giants v Swans matchup.

If we review each of the remaining rounds in terms of how many of the Top 10 games in contains, we now find that:

  • Round 20 has two of them
  • Round 21 has three of them
  • Round 22 has three of them
  • Round 23 has two of them