2019 : Simulating the Final Ladder After Round 21
/The results of the latest 50,000 simulations appear below.
(If you’re curious about the methodology used to create them, you can start here.)
RESULTS
According to the latest simulation results, Essendon are now only slightly better than even-money chances for a Finals berth, and Adelaide only just better than 1 in 3 chances. Meantime, the Western Bulldogs have seen their chances rise to over 3 in 10.
In the race for the Top 4, three teams now have 94% chances or higher, Richmond is about a 3 in 4 shot, and Collingwood almost a 3 in 10 shot. GWS is the only other team with any chance at all.
Geelong are now estimated to be 56% chances for the Minor Premiership, and the Brisbane Lions 32% chances.
In terms of estimated probability of making the Finals, the largest moves this week were:
BIGGEST LOSERS
Essendon (down 28% points to 51%, which is a 43% point drop in two weeks)
Adelaide (down 18% points to 37%)
BIGGEST GAINERS
Port Adelaide (up 26% points to 70%, which is a 52% point increase in two weeks)
Western Bulldogs (up 20% points to 31%)
The big changes in teams’ Top 4 prospects came for GWS (down 44% points), Richmond (up 14% points), and Collingwood (up 13% points).
DETAILED LADDER FINISH ESTIMATES
The detailed view of each team’s estimated probability of finishing in each of the 18 possible ladder positions appears below. Blank cells represent ladder finishes that did not occur even once in the 50,000 simulations, while cells showing a value of 0 represent estimated probabilities below 0.05%.
Seven clear team groupings have now emerged and involve ladder positions 1st to 4th, 5th and 6th, 7th to 11th, 12th to 14th, 15th and 16th, 17th, and 18th.
WINS REQUIRED FOR TOP 8 AND TOP 4
Port Adelaide, Adelaide and Hawthorn are the only teams with better than 1 in 4 chances of playing Finals should they finish on just 11 wins, and St Kilda essentially have no chance even if they end the season with back-to-back wins to reach that tally of 11.
Aside from Adelaide and Essendon, for whom 11.5 wins will be sufficient, all other teams will need at least 12 wins to be estimated 75% chances or better of playing Finals. Essendon, however, even with 12 wins are only about 80% chances of progressing because of their current percentage of just 93.8, which is worse than the five teams immediately below them on the competition ladder.
The estimated probability of the team in 8th spot finishing with just 10 wins fell to zero this week.
Fifteen wins is essentially the minimum requirement for a Top 4 finish now, though even that many wins only gives West Coast, Richmond and Collingwood an estimated 75% chance of taking one of those spots.
The most-likely tally of wins for teams in various final home-and-away ladder positions are now:
1st: 17 wins
2nd and 3rd: 16 wins
4th: 15 wins
5th: 14 wins
6th: 13 wins
7th: 12 wins
8th: 11 or 12 wins
9th and 10th: 11 wins
11th and 12th: 10 wins
13th: 9 or 10 wins
14th: 9 wins
15th: 7 wins
16th: 6 or 7 wins
17th: 6 wins
18th: 3 wins
TOP 2s AND TOP 4s
Next, we’ll look at what the simulations are suggesting are the most-likely combinations of teams finishing in key positions.
For Top 2s, this week we have the situation as shown at right, which still sees a Geelong-Brisbane Lions 1-2 finish the most likely, but with it now occurring in almost 30% of replicates. A Brisbane-Geelong finish is still the next most-likely, it occurring in almost 1-in-5 simulations, just ahead of Geelong-Richmond, Geelong-West Coast, and Brisbane-West Coast finishes.
No other pairing has an estimated probability above 8%.
Across all 10 of the combinations shown here, four different teams appear at least once: Geelong, Brisbane Lions, West Coast, and Richmond. Combined, the 10 combinations represent 99.9% of all of the simulations.
Looking next at Top 4s, we see that the most-likely combination appears in less than 1-in-8 simulations, that being for a Geelong-Brisbane Lions-West Coast-Richmond finish. It’s just ahead of a Geelong-Brisbane Lions-Richmond-West Coast finish, which occurred in 10% of simulations.
Eight other orderings appeared in between about 4% and 8% of simulations.
Across all 10 of the combinations shown here, five different teams appear at least once: Geelong, Brisbane Lions, West Coast, Richmond, and Collingwood. Combined, the 10 combinations represent about two-thirds of all the simulations.
In terms of the Top 8, there were 1,677 different orderings this week across the 50,000 simulations, only four of which occurred in at least 1% of replicates. If we ignore order, we find 18 unique combinations of teams in the Top 8s across the simulations, the most commonly occurring set being the eight teams currently filling the Top 8 spots on the ladder, which turned up in about 27% of simulation replicates, just ahead of the combination that swaps in Adelaide for Essendon, which turned up in about 21%. The third most-likely combination had Western Bulldogs nudging out Essendon and occurred in about 17% of replicates.
LIKELIHOOD OF PERCENTAGE DETERMINING POSITIONS
This week’s results served to make it considerably more likely that some key positions on the final home-and-away ladder will be determined by percentage because the teams in those positions finish tied on competition points.
In the latest simulations, 4th and 5th are separated by percentage in about 30% of the simulations (down 16% points), and 8th and 9th are separated by percentage in about 61% of the simulations (up 11% points). As well, 8th and 10th are separated by percentage in about 38% of the simulations, and 8th from 11th in about 15%.
Also, in just under 1 simulation in 2, 1st and 2nd are separated only by percentage.
TEAM AND POSITION CONCENTRATION
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 saw the uncertainty about the final ordering of the teams decrease quite significantly again, with the Gini coefficients rising to around 0.83. That is, of course, to be expected as only two rounds remain to be played.
At the team level, we saw reductions in uncertainty for all but Essendon and Adelaide, the biggest reductions being for North Melbourne and Fremantle.
Western Bulldogs, Adelaide, Essendon, and Hawthorn now have the most uncertainty, while Gold Coast, Melbourne, Sydney, Carlton, GWS and Geelong have the most certainty about their eventual ladder finishes.
If we adopt a ladder position viewpoint instead, we see that 1st, 6th, and 15th to 18th are the positions with the narrowest range of likely occupants.
All 18 positions except 8th saw increases in certainty, the largest for positions 10th, 13th and 14th. The positions with most uncertainty are now 8th through 12th.
Roughly speaking, we have slightly more certainty this year after 21 rounds than we did last year at the same point about the final ordering of the teams at the end of the home-and-away season (the Gini coefficient then was about 0.82).
GAME IMPORTANCE
Here are the assessments of importance for the remaining 18 games of the home-and-away season. (See this blog for details about how these are calculated.)
Only eight of the remaining 18 games are expected to have a material impact on who makes and misses the Top 8, with Adelaide, Collingwood, Essendon, Fremantle, Port Adelaide, and the Western Bulldogs all involved in two of those eight games.
What’s especially interesting about the top game on the list is that it is expected to alter the Finals’ probabilities of five teams by 9% points or more.
To finish we’ll again look at the importance of the remaining games in terms of their estimated likely impact on the Top 4 (using an equivalent methodology to that we used for assessing the likely impact on the Top 8).
Here, we find Richmond are involved in two of the Top 3 games, and Collingwood in two of the Top 4. In total, only the Top 5 games are likely have a significant impact on the Final 4.
