I would interpret this as his winning being 98% luck and only 2% due to relative chequer/cube play. (You did make SOME errors, after all.) Statisticians may well be critical
of this interpretation.
However, I’ve just analysed a 1-pointer with gnubg playing both sides (so the result is entirely due to luck), and got the following result:
Luck total EMG (MWC) +0.742 (+37.093%) +1.392 (+69.579%)
Luck rate mEMG (MWC) +17.7 ( +0.883%) +32.4 ( +1.618%)
Luck rating None Good dice, man!
Luck adjusted result -17.51% +17.51%
I’m not entirely sure what to make of this.
From: RICHARD BEAGLEY [mailto:address@hidden
Sent: 06 January 2015 09:32
To: Ian Shaw
Subject: Re: [Bug-gnubg] Wrong luck adjusted result on Grandmaster analysis
I have just noticed your comment:
"In other words, without the luck, tophat would have got to 1.95% instead of +50%, and you would have got to -1.95% instead of -50%. His victory was almost entirely
and you could have continued ...........but he would still have won (+2% probability)
This is not the most important thing in my life but I would like to understand the logic.
I monitor the mEMG luck differential - this case (-126.4) was the most adverse in my 383 (ignoring 1 point matches) results todate on DG (OK I'm new here). My
luck adjusted success rate todate is 66.5% cf 63.6% actual and I have had many results changed when luck adjusted. This was an apparent glaring anomaly.
My chequerplay was Expert (v Beginner)
My Cube was Supernatural (v Awful)
Logic would say that I would probably have won if the luck distribution was less extreme.
Surely there is a flaw in your formula which says otherwise!
The luck adjusted result looks OK to me.
You had -12.342% luck and tophat had +35.705% luck.
The actual result was you -50%, tophat +50%.
The Luck-Adjusted result formula = Actual Result – Own Luck + Opponent’s Luck.
Your luck-adjusted result = -50 - -12.342 + 35.705 = -1.953%
Tophat’s luck-adjusted result = 50 – 35.705 + -12.342 = -1.953%
In other words, without the luck, tophat would have got to 1.95% instead of +50%, and you would have got to -1.95% instead of -50%. His victory was almost entirely by luck.
You aren’t the first person to find this confusing.
If the formula were instead (50 – Own Luck + Opponent’s Luck), we would have got 98.05% and 1.95% in your favour.
May be it’s the Actual Result that is the source of the confusion. If this were reported as +100 and 0, rather than +50 and -50, the current formula (Result – Own Luck
+ Opponent’s Luck), would give 48.05% and 51.95%. This indicates that, with the luck removed, your opponent only managed to get from 50% to 51.95%. Again, his victory was almost entirely luck.
I think that (50 – Own Luck + Opponent’s Luck) gives the most intuitive result.
Does anyone know how the other two active bots, XG and BgBlitz, report the luck adjusted result? It might be sensible to standardize on a definition and use that. I’ve
a feeling that XG uses (50 – Own Luck + Opponent’s Luck), but this is only based on my hazy recollection of the discussions at DailyGammon when Miran ran some luck-adjusted tournaments.
Version GNU backgammon 0.90.0 Aug 8 2011
via XQuartz 2.7.7 (xoorg-server 1.15.2) on MAC OSX 10.6.8
Analysis - grandmaster 3 ply
This a single game result (3 point) with extreme differences in move, cube and luck ratings. I should have had a luck adjusted win!
Is this a known bug and / or is my software out of date?
Richard Beagley (tregurtha)