After almost a decade of my AFL
Power Rankings, I’m caving in. (Or I’m expanding my horizons, if you want
to look at it that way.)
I created
my Power Rankings simply so I could get a better indication of each team’s
strength than the ladder was showing me. I’ve never been that interested in
using it to publically tip the results of matches. (Privately, I’ve done so for
several years in various office football tipping competitions – not
that I ever expect it to win the competition.)
But seemingly EVERY other ‘rankings
system’ does tips. And it is interesting to see them. So yes, starting this
year the Wooden Finger is getting into the AFL tipping ‘business’.
How
does it work?
To get the predicted net margin of the home team:
- take the difference between the home team’s and the away team’s ranking points; and
- add on the home ground advantage (if any), where the HGA differs for the men’s and women’s leagues.
To get the expected probability that the home
teams wins, I am using a standard deviation of 36 points or six goals for the
men’s league, and 18 points or three goals for the women’s league. Maybe it should
be a bit more, but since I do all of my HGAs in terms of goals, and for my
purposes it doesn’t make much difference, I’m going with those.
AFLW
Round 1 predictions
Let’s start with my
predictions for Round 1 of the new AFLW season, which is kind of nice in that
there are less ranking systems that do AFLW tips.
Two notes of caution though, related
to the entry of two new teams into the AFLW competition this year. First, the
ranking points for the two new teams – Geelong and North Melbourne – are of
course not based on any previous matches, but are sort of based on their
premiership odds. Second, the entry of those teams has resulted in a fair
amount of player movement, particularly from Collingwood to North Melbourne. It
may take a couple of weeks for the ranking points to adjust to the ‘new’
strength of each playing group.
So there you go. My heart
still lies in ‘explaining’ performance rather than predicting it. Nevertheless I hope these tips add another interesting and informative dimension to the
rankings each week.
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