Thursday, 22 September 2016

26. NEW TERRITORY

So one of a pair of clubs will be in a first AFL Grand Final.
And we learn who that is on Saturday.

The other two have already played off in an AFL Grand Final.

...and yes, there is a bit of 'being pedantic' about AFL vs VFL grand finals.


So as alluded to in the last blog post, the hot tips from the FMI system say its a Derby Grand Final.
HOMEAWAYVENUEPREDICTED RESULT
PFGWS31v3W Bulldogs/FFCShowGWSby29pts
PFGeelong16v28Sydney/SMFCMCGSydney/SMFCby10pts


...but the tips have been wrong about the Bulldogs all finals.
...and that hoary old chestnut about Sydney not handling the bigger MCG all that well.

And stuff.

And the form indicator leans to those tipped, so there is less joy for the non-tipped.
But we all do love an underdog story, so - consider wisely.


Finally...
As posted earlier in the week, the predictors of who play in the grand final, and what percent chance to win it.
TOP 8 - % CHANCE TO PLAY IN WEEK...
Adelaide100100
Geelong10001004119
GWS10001007742
Hawthorn100100
North Melbourne100
Sydney/SMFC1001001005933
W Bulldogs/FFC100100100237
West Coast100
WK 1WK 2WK 3WK 4GF Win

Enjoy your footy.

Wednesday, 21 September 2016

25. TWO GOALS OR TWO

Predicting winners, let alone margins, when finals roll around is a tricky proposition for maths based models and normal tipsters alike.
The carnage seen this week on the Monash Uni scoreboard is testament enough of that. Of the top 20 tipsters, only one selected both winners, and three didn't get a winner at all (not including the two who failed to tip).

So with no qualms, here is the 50% return from this week.
PREDICTED RESULTACTUAL RESULTRATINGS ADJUSTMENTS
Sydney/SMFCby12ptsSydney/SMFCby36ptsSydney/SMFC+14Adelaide-9
Hawthornby12ptsW Bulldogs/FFCby23ptsHawthorn-19W Bulldogs/FFC+15

Margin predictions, each of two, both set for two goal margins, ended up as out by two goals, or the opposite result by about two goals..

And all the above highlights (in combination with your regular AFL top eight as listed in the standard ladder PLUS the rankings table below) just how even the finals have been this year.
And how hard it is to get a feel for who will be the eventual premier.
RANKINGSPre:R 26
TEAMPTSΔPTSΔRK
1Sydney/SMFC142415+1
2Adelaide1401-9-1
3GWS13910
4Geelong13260
5West Coast13250
6Hawthorn1304-18
7W Bulldogs/FFC122416
8Port Adelaide11820
9North Melbourne11750
10Collingwood10960
11Melbourne10220
12St Kilda10170
13Richmond9720
14Fremantle9020
15Carlton8860
16Gold Coast8560
17Essendon6930
18Brisbane Lions6290


And to look at the next week and run some predictive scenarios...
TOP 8 - % CHANCE TO PLAY IN WEEK...
Adelaide100100
Geelong10001004119
GWS10001007742
Hawthorn100100
North Melbourne100
Sydney/SMFC1001001005933
W Bulldogs/FFC100100100237
West Coast100
WK 1WK 2WK 3WK 4GF Win


The four teams are predicted to appear in the Grand Final as above, with the GWS / Bulldogs split as 77 / 23 and the Cats / Swans split as 41 / 59.

After that, the win% for the Grand Final has also been calculated as above, with GWS getting the highest chance, and most likely from a Sydney Derby Grand Final.

Which would be brilliant, because...

Friday, 16 September 2016

MODEST IMPROVEMENT

Back in February, a season preamble post noted the tipping calculations were altered with the aim of increasing accuracy on three measures.

And with a few weeks to play out of the 2016 season, now is as good a time as any to just check back and see if there were any improvements.

The three key measures targeted were for improvements in
- match results tipping accuracy,
- tipped margin error reduction, and
- improved Monash competition score.

In all three measures, the new system has delivered improvement.
THREE MEASURES COMPARISON
MEASUREOLDNEWΔΔ%
CORRECT TIPS14014110.7%
MAE (Margin Error)30.630.4-0.2-0.7%
MONASH SCORE17561773171.0%
MONASH POSITION17th14th3

A small improvement, but forward progression none the less.
Yes the red negatives for MAE indicate a better performance as you want to be as close to zero as possible with this measure.
Also added in is the Monash Position data, which is not critical, and hence shaded grey.

Reducing MAE is also linked to improving the Monash score, as the Monash score is built around margin accuracy, with points awarded to margin differentials separated into brackets.

Comparing those brackets under the two systems yields some improvements as well.
MARGIN BRACKET COUNTS
01-67-1213-1819-2425-3031+
OLD1272326131993
NEW3272126151892
Δ2--2-2-1-1

With a prima facie look at that table, you could make a case for the two more 'exact' tipped games as having come from the immediate 2 brackets above the zero point, as well as the 2 more results in the 19-24 point bracket as having come from the 25-30 and 31+ point brackets.

It will need further investigation to determine exactly if that's the case. Or maybe its just best left alone.


Finally, the changes made to the algorithm also impacts a teams rating, and with the multi-step taper employed under the new system, the changes had different impacts at different stages of the year.
But as the table below shows, over the space of the year (to date), these were minimal once accumulated.
CURRENT (NEW) SYSTEMOLD SYSTEM
RANKINGSvs Old SystemRANKINGS
TEAMPTSΔPTSΔRKTEAMPTS
1Adelaide14105+11Sydney/SMFC1407
2Sydney/SMFC14092-12Adelaide1405
3GWS13914-3GWS1387
4Geelong13263+24Hawthorn1327
5W Bulldogs/FFC13250-5W Bulldogs/FFC1325
6Hawthorn1323-4-26Geelong1323
7West Coast12083-7West Coast1205
8Port Adelaide1182-4-8Port Adelaide1186
9North Melbourne11751-9North Melbourne1174
10Collingwood1096-3-10Collingwood1099
11Melbourne10223-11Melbourne1020
12St Kilda10173-12St Kilda1015
13Richmond972-6-13Richmond977
14Fremantle902-4-14Fremantle906
15Carlton8861-15Carlton885
16Gold Coast8563-16Gold Coast854
17Essendon693-3-17Essendon696
18Brisbane Lions629-1-18Brisbane Lions630


The differences above are really quite minor, but yet yielded a 1% improvement.
Clearly a new and perhaps more radically modified algorithm will need to be developed.