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Re: [Bug-gnubg] Wrong luck adjusted result on Grandmaster analysis


From: Ian Shaw
Subject: Re: [Bug-gnubg] Wrong luck adjusted result on Grandmaster analysis
Date: Tue, 6 Jan 2015 10:29:54 +0000

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:

 

                                      tregurtha            tophat             

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.

 

n  Ian

 

From: RICHARD BEAGLEY [mailto:address@hidden
Sent: 06 January 2015 09:32
To: Ian Shaw
Cc: address@hidden
Subject: Re: [Bug-gnubg] Wrong luck adjusted result on Grandmaster analysis

 

Ian

 

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 by luck."

 

and you could have continued ...........but he would still have won (+2% probability)

 

How???

 

This is not the most important thing in my life but I would like to understand the logic.

 

Regards

Richard

 

 

 

 

 

 


From: RICHARD BEAGLEY <address@hidden>
To: Ian Shaw <address@hidden>
Cc: "address@hidden" <address@hidden>
Sent: Tuesday, 6 January 2015, 8:30
Subject: Re: [Bug-gnubg] Wrong luck adjusted result on Grandmaster analysis

 

Ian

 

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!

 

Regards

Richard

 

 


From: Ian Shaw <address@hidden>
To: RICHARD BEAGLEY <address@hidden>; "address@hidden" <address@hidden>
Sent: Monday, 5 January 2015, 14:17
Subject: RE: [Bug-gnubg] Wrong luck adjusted result on Grandmaster analysis

 

Hi Richard.

 

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.

 

n  Ian

 

From: bug-gnubg-bounces+address@hidden [mailto:bug-gnubg-bounces+address@hidden] On Behalf Of RICHARD BEAGLEY
Sent: 04 January 2015 16:08
To: address@hidden
Subject: [Bug-gnubg] Wrong luck adjusted result on Grandmaster analysis

 

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?

 

Regards

 

Richard Beagley (tregurtha)

 

 


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