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## Re: RE: Réf. : [Bug-gnubg] Understanding the stats

 From: Massimiliano . Maini Subject: Re: RE: Réf. : [Bug-gnubg] Understanding the stats Date: Fri, 22 Sep 2006 17:27:22 +0200

```>The way I read the results below, Opponent won 3 points, but if
>he hadn't been so lucky he'd "only" have won 1.958 points. However,
>he is still coming out ahead, which means that he must have more
>net skill. However, the error analysis says Opponent was a worse player.

I think that the reason is simply that the luck adjusted results do not
take into account the error rate: it adjusts the actual result
according *only* to luck.

Only combining luck and error rate adjustment one could define an
advantage that *always* behave as expected (I've been luckier playing
worse,
then my edge is negative).

I don't know how Snowie computes a player's advantage, but I suppose that
it
depends only on the error rate (and not on the luck). And at the moment
there's no such a thing in gnubg (the closest thing is the FIBS rating
difference, depending only on the error rates and for match only).

BTW, notice that the stats said :

>Advantage (actual) in ppg          +0.4286        - 0.4286
>95% confidence interval (ppg)       3.1388          3.1388
>95% confidence interval (ppg)       0.9709          0.9709

The 95% confidence intervals are wider that the ansolute values of the
enough to correctly estimate the advantage purely on luck.

If you play a looooong session, luck will cancel out and the luck
supposed to be a good estimation of your real advantage, since the
session was loooooong).

The only thing that luck adjustement does is the following : in a
Notice that that's true in Albert's case: assuming he his a better
closer to a negative number than the actual advantage (+0.4286) is.

error rates ... could it be as easy as subtracting the error rate
(per game) from that ?

At least, that's my understanding of the thing.

MaX.

```