AFL Power Ratings
 

These are my own power ratings for 2004. I plan on using them in 2005.

Port 92.5
Bris 92.8
St K 92.2
Geel 91.7
Melb 91.1
Syd 90.7
WCE 90.4
Ess 90.3
Fre 90.1
Kang 90.1
Carl 87.8
Ade 89.6
Coll 89.1
WBD 87.5
Haw 85.8
Rich 85.6

How do I turn them into percentage probabilities?

Benny

Can you please tell me how you arrived at those figures??? Then I might be able to help.

Port allowed 1823 pnts which you multipled by 10 then divide the pnts scorded. Subtract that from a hundred.

E.G Port 1823*10= 18230/2413=7.5 100-7.5= a power rating of 92.5

Does that help?

Benny

Take Geelong and Melbourne. You've got Geelong 91.7 and Melbourne 91.1. I'm assuming that it basically means Geelong is a six point better team than Melbourne on a neutral ground??? Is that right?

I haven't factored in the home ground advantage.

Benny

If you want to work out ratings based on this years Home & Away, you could possibly think about this: Take a team's winning % and add it to their for & against % and then divide by two to get an average score. This should then give you some indication of the points differences between the teams.

In this case, it would be:
105.0 Brisbane
104.9 Port Adel
100.3 St Kilda
94.1 Geelong
87.8 Melbourne
83.2 Sydney
81.4 West Coast
78.5 Essendon
75.3 Fremantle
72.9 Kangaroos
66.0 Adelaide
63.8 Collingwood
63.6 Carlton
51.2 W.Bulldogs
44.2 Hawthorn
43.7 Richmond

That's not counting the Finals series though. If you did that, of course Port would be ahead of Brisbane.

Thanks. I might try it next year, but after a couple of rounds. What do you think?

Benny

How do I covert the ratings into a percentage figure?

Benny

Okay, let's use your ratings. Take a game between say Carlton and Hawthorn at the MCG. You have Carlton on 87.8 and Hawthorn on 85.8. I've taken the liberty of just assuming that every .1 of a point is equivalent to 1 point on the scoreboard, because in the case of your ratings, I think that's not a bad assessment. Therefore, we have Carlton winning by 20 points.

Mo had a good formula for working out fair prices. It probably sounds a bit complicated, but I think it works well. I think the magic number was 0.955, wasn't it Mo? To find out the true value price for the favoured team Carlton, you multiply 0.955 by itself 20 times (once for every point you have Carlton winning by) and then add 1. Doing that, you end up with $1.40. To get Carlton's % chance, you simply divide 1.40 into 100 and you get 71.42%. Therefore Hawthorn's % chance is obviously 100 - 71.42, so 28.58%. Divide 100 by 28.58 and you get Hawthorn's value price of $3.50.

So therefore in that match, you would get:
Carlton (71.42%) $1.40
Hawthorn (28.58%) $3.50

Personally, I think it's a tad dangerous using ratings based on this year's results. I always like to use my own opinion. I've already done a revised set of ratings for next year. Obviously, I'll probably change it again slightly by the time the season rolls around, but at the moment, my ratings are like this:
126 Port Adel
120 St Kilda
117 Geelong
114 Brisbane
111 Sydney
108 West Coast
105 Essendon
102 Collingwood
99 Fremantle
96 Melbourne
96 Carlton
93 Adelaide
90 Kangaroos
84 West B'dogs
84 Hawthorn
84 Richmond

If you want, I could work out a table based on that formula of Mo's, so that you wouldn't have to work it out for every single game.