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thebig-o



Joined: Apr 14, 2005

Post   Posted: Jun 02, 2005 - 19:58 Reply with quote Back to top

I’ve been looking at the coach rankings formula because we are planning to use it as a tie-breaker for our fumbbl group. We want to compare coaching rating for games inside the tournament.

Anyway, I put a spreadsheet together to calculate the rating but must be doing something wrong because the results don’t make sense. I am hoping someone can tell me where I’m going wrong here.

The game I am calculating for is between two new coaches with the following stats:

Team A CR (Ro) 150 TS (S1) 99
Team B CR (Ro) 150 TS (S2) 113

In terms of the calculation I have the following

Dr = 150 – 150 = 0
Dt = 100 * ( (99 / Min (99,113) – 113 / Min (99,113)) = 100 * ( 99/99 – 113/99) = -14.1414
S = 1 ( the ST 99 team won the match)
K = 2
P = 1 / (1+10^(0/40 + -14.1414/70) = 1/ (1+10^-2.0202) = 1 / 1.628 = .614
Rn= 150 + 2*(1-.614) = 150.7715

Now the New CR looks okay but I have a problem with the Win Probability result. It seems like a lower ST team should have a probability below 50%

It also gets odd when you use a different set of stats:

Team A CR (Ro) 150 TS (S1) 100
Team B CR (Ro) 160 TS (S2) 150

In terms of the calculation I have the following

Dr = 160 – 150 = 10
Dt = 100 * ( (100 / Min (100,150) – 150 / Min (100,150)) = 100 * ( 1 – 1.5) = -50
S = 1 ( the ST 99 team won the match)
K = 2
P = 1 / (1+10^(10/40 + -50/70) = 1/ (1+10^-.46429) = 1 / 1.34332 = .7444
Rn= 150 + 2*(1-.7444) = 150.52

I think the issue is the Prob calc . Can anyone help?

BTW – I posted to this discussion because the data came from the User Guide.
Mully



Joined: Aug 02, 2003

Post   Posted: Jun 02, 2005 - 22:10 Reply with quote Back to top

Go through the old threads (search) for when the Rankings were recalculated. Christer and I had a nice long discussion on these probabilities.

You are right, they dont make sense from your standpoint. But what I gathered from the Big C was this is to be used to affect coach rankings and NOT to try and judge what is considered a tru 50/50 game.

Net, dont worry things you have no control over.

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