Matter of Stats

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2019 : Simulating the Final Ladder After Round 6

Is it really only Round 6 and am I, honestly, proffering opinions about the end of the home-and-away season in a year where even the bookmakers have been only slightly more useful than a coin in tipping winners? As I kid, I reckon I was pretty steadfast in the face of relentless peer pressure (yeah, I was a geek the too), yet here am I, at my age, guessing into the wind about games to be played in August …

Anyway, enough of that, the latest simulations of the home and away season appear below.

(If you’re curious about the methodology used to create them, you can start here.)

RESULTS

So, if MoSHBODS - and the simulation methodology I’ve imposed upon its opinions - is somewhat rightish, the team that finishes 1st this year will only win about 7.5 games more than the team that finishes last. Well, we all know that expectations are often disappointed …

Here’s what the simulations “reveal”:

The week’s biggest losers in terms of Expected Wins, according to the simulations, were Gold Coast (down 1.2 Expected Wins), and St Kilda (down 0.8), while the biggest gainers were Brisbane Lions (up 1.1), and Richmond and Adelaide (up 0.8 each). Frankly though, it feels like even the 50,000 simulations are going “don’t ask us!”.

Ignoring that, looking at the simulations through the lens of making the Finals, we have:

  • St Kilda (down 16% points)

  • Gold Coast (down 12% points)

  • West Coast (down 10% points)

  • Brisbane Lions (up 21% points)

  • Adelaide (up 14% points)

  • Richmond (up 13% points)

As much as I’m loathe to say it, right now I pity the bookmakers trying to frame markets for anything much beyond next week.

TEAM AND POSITION CONCENTRATION

As we talked about last week, one way of measuring how much uncertainty there is in the competition is to use the Gini measure of concentration commonly used in economics for measuring income inequality to quantify the spread of each team's estimated final ladder positions across the 50,000 simulation replicates, and to quantify the concentration in the probabilities across all the teams vying for any given ladder position.

This week, we see that, even with the absurdly high levels of uncertainty generally about game results, teams’ final positions have become generally a little clearer, the average Gini Coefficient having moved fro 0.38 to 0.45.

In particular, Geelong, Carlton and Sydney seem to have resolved their final positions just a little more this week, with Geelong now assessed as 40% chances for the Minor Premiership, Carlton 22% chances for the Spoon, and Sydney 21% chances for the Spoon and 17% chances for finishing immediately Spoon-adjacent.

Least certain are the finishes for West Coast, Fremantle, Hawthorn, St Kilda, Adelaide and Essendon, all of them at least about 7% chances of finishing in any of 8 different ladder positions.

Looking more broadly, every team except North Melbourne, Port Adelaide and St Kilda, became at least a little more certain about their ultimate ladder finish this week.

Next, reviewing the ladder position Gini coefficients, which appear at the right of the table, we see that 1st and 18th remain the positions with the narrowest range of likely occupants at season's end (Geelong and Carlton having, as mentioned, already made significant claims to those positions), whilst positions 8th through 13th have the widest range of potential occupants. For each of those ladder positions there are at least five - and as many as eight - teams with roughly 8% or greater chances of occupying them come the end of Round 23.

Again looking more broadly, every ladder position became at least a little more certain this week about which team will occupy it come the end of the home-and-away season.

GAME IMPORTANCE

Here are the updated assessments of the 30 most-important games between now and the end of the home-and-away season. (See this blog for details about how these are calculated.)

Twenty-two of the 30 games shown here were also estimated as being in the top 30 last week (and one on last week’s list was a Round 6 game, which obviously can’t still be on the list). That is, frankly, an astonishing level of stability (though I recognise that being stubbornly wrong or ill-advised isn’t grounds for celebration).

It’s also true that half of the games estimated as being most influential come from rounds 17 to 23, which just emphasises (at least in part) the influence of this year’s conservative methodology regarding games way into the future. (Gotta be honest: I’m feeling a lot more relaxed about that methodological approach right now.)