Re: [Bug-gnubg] Suggestion for change of rates/ratings

[Christian Anthon]

On Thu, Mar 30, 2006 at 05:03:23PM +0100, Ian Shaw wrote:
>  
> 
> > -----Original Message-----
> > From: Christian Anthon on 30 March 2006 15:10
> > 
> > it is well known that gnubg judges the players harder than snowie.
> > Snowie error rates seems to be defacto standard when judging 
> > players. To see how gnubg and snowie error rates compare I 
> > tried downloading 25 or so matches from Hardye's site, all 
> > played between more or less world class players and most of 
> > them quite long. They were analysed using gnubg 2ply/2ply.
> > 
> > To summarise:
> > 
> > snowie_m  snowie_c   snowie  gnubg_m  gnubg_c   gnubg
> >     3.91      1.66     5.58     9.36    21.51   11.25
> > 
> > So given these numbers I suggest that we adapt snowie's 
> > rate/rating groupings, but that we divide the gnubg 
> > move-error and total-error rates with 2 and the cube error 
> > rate by 4. That way it will be easy for people to understand 
> > the numbers and to compare an intermediate snowie player to 
> > an intermediate gnubg player. Of course the move ratings and 
> > the total ratings of gnubg will not be directly comparable. 
> > But it will complicate things unnecessary to make it any different.
> 
> The chequer play discrepancy arises because gnubg doesn't include forced
> moves in the calculation, whereas Snowie includes all moves.
> 
> The cube play discrepancy arises because gnubg only includes actual or
> (arbitrarily) close decisions in the calculation, whereas Snowie
> includes all cube decisions.

I know both of these facts.

> 
> Gnubg calculates errors differently because the discussions on this list
> concluded that forced moves don't count as decisions at all, just like
> you can't make a cube error if the opponent holds the cube. This makes
> more sense to me.

And to me.

My point was not all that clear I can see. What I would like to achieve
is.

1) That an expert snowie player is an expert gnubg player, and
vice versa.

2) That an expert chequer player is an expert cube player, and vice
versa.

3) That people would actually cite the gnubg rates and ratings, which
nobody does today.

4) That gnubg's system is easily understood and that the numbers
translates to snowie's in a straight forward way.

The number suggest that the following relations apply for a large number
of players matches, and match_lengths:

total-snowie-error : total-gnubg-error : gnubg-move-error : gnubg-cube-error 

      1            :         2         :        2         :        4

Right now gnubg uses the same rate -> rating translation for total,
moves, and cubes, and especially for cubes the translation is much too
tough.

I only suggest changing the translations, not the numbers. 

gnubg would then report you as a borderline world class/expert when
your snowie error rate is 4.4, your gnubg error rate is 8.8, and your
gnubg cube error rate is 17.6.

I hope it is clearer this time.

Christian.