Re: [Bug-gnubg] Suggestion: equivalent # of games played in roll outs thx to var. reduction

[Joern Thyssen]

On Tue, Oct 14, 2003 at 02:49:15PM +0200, olivier croisille wrote
> I'm aware that the issue was raised in the past various times, I'd just 
> like to know the current status, if any :
> 
> - is it on the agenda at all?

yes, it's noted on the TODO list.

> - is it on the agenda but with a very low priority level? (which would 
> perfectly make sense, regarding a more or less cosmetic feature)

noone is working on it

> - is it hard to compute

no

To compute it you need the ratio between the calculated standard error
without variance reduction and the calculated standard error with
variance reduction. The equivalent #games varies with the square of this
ratio, e.g., a 36 game rollout where the SE without and with VR is 0.01
and 0.005, respectively, the #equiv games is 4*36=144.

> implement?

yes :-)

I'm guessing that we need to save the non-VR equity and SE (internally
and externally) in order to be able to resume rollouts. This is the
critical point, as it requires changes to many places in gnubg.

> Incidentally, on the 'promotion' side (if ever needed) I think this would 
> show even better the top quality of roll outs enabled by Gnubg

Personally I don't find the #equiv games that interesting. The SEs and
JSDs  are much more interesting -- it doesn't help you much to know that
your rollouts is equivalent to 10,000 games if the two moves you're
rolling out are only separated by one tenth of a SE.

All rollouts are normally performed with VR, so what's the point of
knowing that the #equiv games for a non-VR rollout, since nobody would
do such a rollout (unless they only have S3.2 and enable chequer play
according to score).

Other opinions on this subject?

Jørn

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