Wednesday, 1 October 2014

27. Final Called

And with that dee-stroyation by Hawthorn, the sun sets on Season 2014. One that had us ranking the Hawks as the best team of the season for all weeks bar after round 22, where they were pipped by Sydney by 8 points.

The Swans also were great contributors all year, starting as our 4th ranked team, and finishing 2nd. One one occasion, as above, the were our best team, and they also spend the early part of the season ranked 7th. From round 12 onward though they were a solid 2nd best ranked.

We tipped the Hawks to win, but not by anywhere near the actual margin.

Joining us in tipping Hawthorn was one other of the Guardian's statistical tippers (Robert from aflpredictions), and also Ted Hopkins, formerly of Carlton and Champion Data.

Both Ted and Robert were in general agreement with our calculations... that the Hawks would win... just.

The folks over at FootyForecaster also went for the Hawks, but by 11 points.

We will leave it to others to write about why so many other pundits went for the Swans to win.

Monash Result:
Heading into the last game of the year, our tips would have scored 1899 points under the Monash Uni tipping competition rules. This score would have been 8 points ahead of the nearest competitor.

With Hawthorn winning, we collect another 10 points, and with the maximum on offer for this game being 16, we are confident in saying our system would have won the Monash Uni competition.

EDIT: Confirmation that the best Monash score is 149 correct tips and 1891 points.
Or score of 1899 points and 150 correct tips would have won the 2014 competition.

Final comments:
That wraps up the rankings table from us for the year. Your finishing order is at right with surprise packets Adelaide in 5th and West Coast also 8th having missed the finals. Can they be genuine contenders in 2015?

Note also there is correaltion between our rankings and those at FootyForecaster as well as Troy Wheately's Power Rankings as well.

We will make further assessment on the table in coming weeks.

Also, after a year using Open Office as a spread sheeting tool, we will likely move to a new format in 2015, in line with the re-design of the site.

Thanks to all who have read the blog and followed the tips... I know a few have done well in their respective tipping competitions, and we hope to have a better year next year after a few more fine-tunes to the system.

Saturday, 27 September 2014

Special Edition: Mainstream

Sometimes during the week we received unsolicited e-mail. Normally skeptisism creeps in and it gets junked.

On rare occasions it's someone interested in the blog in a real sense.
We have had a few inquiries from gambling businesses, and these get the due consideration required.
But more often than not it is junk.

This week it was a very different e-mail that landed on the virtual desktop of the Institute.
It was a request from Nick Evershed of The Guardian to be included in a piece on statistical modelling and tipping of AFL football, as a lead-in peice to the AFL Grand Final.

So, once the initial shock settled, we submitted our answers (on the back of a postcard, addressed to PO Box 999 in your Capital City, as always), and wondered what would become of it.

And so, yesterday (26 Sep) we find the first breach of the nickel and dime, and incredibly part-time, FootyMaths Institute into the mainstream press.

For posterity (and without permission, but attribution), below is our section of a bigger article on statistical tipping of football.

Read it all here:

AFL grand final: Our stats experts go for a Hawthorn win … just

and our bit is extracted as below.

Prediction: Hawthorn win by one point
Model accuracy: “Over 70% return on tips”
The FootyMaths predictions are determined through a modified Elo ratings system. They are modified by a few factors, but in effect I try to keep the system as simple as possible.
It is purely based on score results, with the application of a home ground advantage bias, dependent on certain conditions (ie not applied to derbies/local matches, or teams using other venues for limited games). Injuries, weather and ‘umpire bias’ are not considered as they could bring subjectivity into the system.
It is a relatively simple system. The rankings points indicate a team’s strength, and we determine an outcome of a match based on them. If a team performs better than predicted, they get a points increase. Fail to meet expectations, and they get a points decrease.
In this finals series, the best two ranked teams are in the grand final. Port Adelaide proved the surprise, reaching as far as they did... perhaps indicating too long of a lag in my change factors.
In terms of success, I look to a few measures as (for want of a better phrase) KPIs.
The first is the percentage of correct tipping over the season.
It has not been easy to maintain over a 70% return on tips, with a ‘best season’ return of 82.1% correct in both 1934 and 1966 (when retro applying the model).
In the modern era (post 1997 and Fitzroy’s demise, when the AFL took the stand to guarantee club financial stability), breaking 70% has been much harder. It has been a period of unparalleled equality in the AFL/VFL’s history. We have only got over 70% again with the introduction of the Suns and GWS.
As I not only tip winners, but also game margins, the more critical numbers are the MAPE of the margin tips (Mean Absolute Points Error) which is effectively the ‘distance from the pin’ of our predicted margin to the actual margin. I am tracking as 30.0 now, which is a reasonable number. Under 30 is considered good (so I have been told!).
For me, it all started out as a bit of fun and a hobby idea. I entered the blog business without even considering if anyone else did such a thing, or would be interested in reading it.
I was a regular reader of Russell Degnan’s idlesummers blog where he ranks all international cricket teams. Russell was the inspiration and provided a lot of the model basics. Without Russell, FootyMaths wouldn’t exist.
As to the grand final tip, it is one of the closest games of the year for us. Only 0.6 points separate the teams, which when converted to a match day score says it will be a one-point win to Hawthorn. But I was similarly wrong about Hawthorn in 2012, tipping them by 12, and the Swans won by 10.
For my dad’s sake, I hope the model is wrong again.

Thursday, 25 September 2014

27. Last Call

We have the two best teams as determined by our rankings system, and that most people consider as best in 2014, ready now for the Grand Final.
And with Sydney's great win last week, they earnt enough points to all but tie with Hawthorn in our rankings.

This makes tipping this Grand Final difficult on our calculations.
As a result of the calculations, it is the closest Grand Final we have ever calculated a tip for in the 3 years we have been blogging.

The last time we had such a 'predicted' close Grand Final (by retro-fitting the calculations through the 118 seasons of VFL/AFL football) was for West Coast vs Sydney II, in 2006.
We tipped Sydney to win by 1 point, and the classic rematch went to West Coast, by 1 point.

In terms of one of our key tipping indicators, the below tip is critical for the year.
Our Monash Uni score (as right) would have us sitting on top of the table, 8 points clear.
But a correct tip is 10 points.
If this tip is wrong, and out by shedloads, a (nominal) win of that competition will be squandered.

Saturdays game is a big moment for both teams, fans and sponsors and assorted hangers on. And in our little corner of the mathematical tipping world, its also critical.

PS... Oh yes, and I wont see a minute of the game. An important party in Brisbane beckons.


So that's a one point win to Hawthorn from us.
...and with these two teams 'we might be back here next week' to tip it all again.