RE: [Bug-gnubg] Stats labels

[Ian Shaw]

        From: Robert-Jan Veldhuizen
        Sent: 29 February 2008 11:29
        
        It would also be nice if something could be done about GNUBG's
way to harsh cube decision labels. Since they only get divided by the
number of "close" or actual decisions, the error per move here tends to
be very high when compared to the checker play error per move.
Unfortunately GNUBG doesn't allow for this when giving its label (I
believe the labels are still based on GNUBG's old system where all cube
decisions were being counted). A new range for the labels would be more
realistic.
        
----

I think it's time to drop the "close" or actual decisions criterion, and
use all moves, more like Snowie. The criterion is so arbitrarily
selected that it's almost meaningless. So it's not good science.

In fact, I'd go further and say that gnubg should adopt Snowie's way
completely, and use both players decisions. 

Serious players today are familiar with the Snowie system, and use it to
discuss peoples playing strength. No-one uses gnubg ratings in the same
way.

Using only one rating method would simplify the code and the display.

There are arguments against Snowie's method, because it seems odd to
uses both players moves for evaluating one players error rate. However,
Douglas Zare argued well for the Snowie method. I'll quote a paragraph
of his article below.

"The number of moves you make is very close to the number of moves your
opponent makes, but the number of unforced moves may be quite different.
In fact, your playing style can affect the ratio of unforced moves you
make to the number of unforced moves your opponent makes. If you blitz
your opponent too often at DMP and often achieve strong 5 point boards
and closeouts, then you will have many more unforced moves than your
opponent will. It is possible to give up more equity overall, while gnu
reports that you are giving up less equity per unforced move. It is very
hard for this to happen with Snowie's measurement."

There's more in Douglas's GammonVillage article
http://www.gammonvillage.com/backgammon/news/article_display.cfm?resourc
eid=5033


-- Ian