Re: [Bug-gnubg] new cube rating computation

[Joern Thyssen]

On Wed, Aug 07, 2002 at 10:28:38AM +0200, max-d wrote
> hi,
> The new cube rating computation does not look fair ...
> i can't agree i'm a beginner cube user  just because of this wrong take !
> 3 point match
> 
> 
> Move number 11: O doubles to 2
> 
>  GNU Backgammon  Position ID: bJ2DAyDMngcHAA
>                  Match ID   : MBlgAAAAAAAA
>  +12-11-10--9--8--7-------6--5--4--3--2--1-+     O: gnubg
>  | X           O    |   | O  O     O     X |     0 points
>  | X           O    |   | O  O     O       |
>  | X           O    |   | O                |
>  |             O    |   | O                |
>  |                  |   |                  |
> ^|                  |BAR|                  |
>  |                  |   |                  |
>  |                  |   |                  |
>  | O           X    |   | X                |
>  | O           X    |   | X     X  X       |     Cube offered at 2
>  | O           X    |   | X  X  X  X       |     0 points
>  +13-14-15-16-17-18------19-20-21-22-23-24-+     X: user
> 
> * user accepts
> 
> Alert: wrong take ( -0,53%)! [doubtful]
> Cube analysis
> 2-ply cubeless MWC  55,67%
>   0,729 0,108 0,001 - 0,271 0,036 0,001
> 1. Double, pass         60,00%
> 2. Double, take         60,53%  ( +0,53%)
> 3. No double            58,88%  ( -1,12%)
> Proper cube action: Double, pass

The new cube rating divides your cube errors with the number of actual
or close cube decisions. If you in the game above only had one actual
cube decision and no close ones, then you'll get the beginner rating.

In general, I would say that it's fair that someone is rated beginner if
he only had one close cube decision and managed to blunder on it. Of
course, if the threshold is too low it's not fair.

In fact, we have been discussing changing the threshold for when a cube
decision is considered close from the current 0.1 (in terms of equity
difference) to at least 0.2, but perhaps even up to 0.4, but no decision
was made.

Jørn

-- 
Joern Thyssen, PhD
Vendsysselgade 3, 3., DK-9000 Aalborg, Denmark
+45 9813 2791 (private) / +45 2077 2689 (mobile) / +45 9633 7036 (work)