GNU Backgammon

Forum Archive : GNU Backgammon

MWC versus Equity (EMG)

From:   Ken
Address:   none
Date:   24 April 2005
Subject:   Gnu MWC vs Equity
Forum:   GammOnLine

I have always used the MWC setting in GNU to analyze matches. A friend
has recommended that I do not use it and look at equity instead. His
reasoning is:

"I've noticed a few times on GammOnline that you look at your gnu
rollouts with MWC rather than money equity. I used to do this as well,
but someone suggested I change, saying "why let the same move some time
be a 2% error and sometimes an 8% error depending on the score." At
first I was skeptical but switched and am VERY glad I did. I think you
get a much more consistent view of correct checker play and can later
adjust for match score if necessary. Try it, I think you'll like it."

The reason that I have always used MWC for matches comes from my reading

Quoting from there: "You may also prefer to see the Match Winning
Chances of the moves instead of the equity. This shows the chances of
winning the match as opposed to the evaluation according to a single
game. To do so, press the MWC button:"

Because I am interested in winning the match much more than winning a
game, I choose to look at MWC. Also, I thought that if Gnu was looking
at a single game, I would miss my mistakes in gammon go and gammon save
situations. However, this does not seem to be the case. It seems that
the moves are always ranked the same in either setting.

Which setting do people use and why? Do you use one or the other based
on a situation?


Robert-Jan Veldhuizen  writes:

If GNUBG plays a match and you set it to display equity instead of MWC,
it uses EMG, which is Equivalent Money Game equity. This is not the same
as simple money equity; it allows for the matchscore.

With EMG, a win on the current cube value is still +1 and a loss -1,
however gammon wins or losses may not be +2 or -2, idem for backgammons
and doubled games, etc. This is because of the different gammon values.
GNUBG calculates all these using MWC.

What's important to understand is that EMG and MWC are lineary related,
so rankings will always be the same, and various differences between
plays will be in the same proportions.

I find EMG to be far superior for learning purposes. It's very hard to
get a feel for MWC at all sorts of different scores.

Also, it's much easier to see where one stands with the cube, since
passing always means -1 and cashing +1 with EMG.

I only use the MWC button sometimes to see how much MWC % is at stake in
the current game, like: how much more important is the 3-away 2-away
game, center cube, compared to the first game in a 11pt match.

HappyJuggler0  writes:

I always use equity but I started with MWC. Then one day I was
dumbfounded by how badly a particular move was. I posted it on another
forum and discovered that my problem was that I was treating MWC the
same regardless of score, while with equity you don't have that problem.
(The move was rather bad in equity too by the way lol). MWC misleads you
into thinking a misplay of 53 on the opening roll in an 11pt match at
0-0 is much less of a problem than it is at 10-10 in the same match.
Pretty much the same error (except for gammon implications) but
radically different numbers. This skew based on score makes it much
harder to detect recurring "types" of big mistakes since the numbers
keep changing on you. But if yyou are on the bar and roll 61 and keep
seeing that 8/2 is roughly the same blunder it tends to stick in your
mind after a while and you can adjust the way you play.

It is also extremely useful for cube purposes. By seeing the cube
"problem" in terms of 1.000 (cubeful) and by seeing so many analyses I
got much better at my cube skills at a rather quick rate. Just remember
that the match score does affect things and you need to cube earlier
with a match deficit etc.

Once I made the switch to equity and once I got used to the new numbers
never looked back.
Did you find the information in this article useful?          

Do you have any comments you'd like to add?     


GNU Backgammon

Analyzing GamesGrid matches  (Roy Passfield, Dec 2001) 
Batch analysis tool  (Øystein Johansen, June 2004)  [GammOnLine forum]
Cache size  (Ned Cross+, Mar 2004)  [GammOnLine forum]
Compiling for Windows  (Øystein Johansen, Jan 2002) 
Edit mode removing checker from bar  (Scott Steiner+, May 2003) 
Entering an annotated match  (Albert Silver, Dec 2003)  [GammOnLine forum]
Error rates: Gnu vs. Snowie  (Raccoon, Mar 2006)  [GammOnLine forum]
Even-ply/odd-ply effect  (Raccoon, Nov 2004) 
Even-ply/odd-ply effect  (Tom Keith+, Oct 2003) 
Even-ply/odd-ply effect  (Scott Steiner+, Dec 2002) 
Filter settings  (Robert-Jan Veldhuizen, Nov 2004)  [GammOnLine forum]
Gnu 0.13 versus Jellyfish and Snowie  (Torsten Schoop, Aug 2003) 
Gnu 0.13 vs. Snowie 4  (Albert Silver, June 2003) 
Gnu 0.14 vs. Jellyfish  (Michael Howard+, July 2003) 
Gnu versus Snowie and Jellyfish  (Michael Depreli, Oct 2005) 
How luck factor is calculated  (Gregg Cattanach, Aug 2002) 
How rollouts work  (Gary Wong, July 1999) 
How to enter an illegal move  (Øystein Johansen, Aug 2003)  [GammOnLine forum]
Importing .gam files  (PAR+, Mar 2005) 
Importing PartyGammon matches  (rew+, July 2006) 
Improving your game using GnuBG  (D.U.G.+, Nov 2002) 
Installing on Windows  (maareyes, Oct 2001) 
Interpreting JSD's  (Adrian Wright+, Feb 2005)  [GammOnLine forum]
JSD's and confidence intervals  (Daniel Murphy+, Jan 2005) 
Logging rollouts  (Øystein Johansen, Oct 2004)  [GammOnLine forum]
Luck rate  (Kees van den Doel+, May 2002) 
MWC versus Equity (EMG)  (Ken+, Apr 2005)  [GammOnLine forum]
Manually entering first roll  (Andreas Graf+, Apr 2005) 
Match equity tables  (Raccoon, July 2005)  [GammOnLine forum]
Personal reflections  (Louis Nardy Pillards, Sept 2002) 
Playing two computers against each other  (Stanley E. Richards+, Mar 2008)  [GammOnLine forum]
Python scripting  (Øystein Johansen+, Nov 2004) 
Quasi-random dice in rollouts  (Ian Shaw, Mar 2004)  [GammOnLine forum]
Question marks in game list  (Jim Segrave, July 2005) 
Questions and answers  (Jim Segrave+, Jan 2003) 
Questions and answers  (Jørn Thyssen, Aug 2002) 
Restarting a rollout with different settings  (Jim Segrave, Apr 2005)  [GammOnLine forum]
Restarting a rollout with different settings  (Robert-Jan Veldhuizen, Apr 2004)  [GammOnLine forum]
Rollout settings  (geoff arnold+, Apr 2007) 
Rollout settings  (Stick+, Nov 2005)  [GammOnLine forum]
Rollout settings  (Robert-Jan Veldhuizen, Mar 2004)  [GammOnLine forum]
Rollout settings  (Ian Dunstan, Aug 2003)  [GammOnLine forum]
Rollout settings for the impatient  (Robert-Jan Veldhuizen, June 2004)  [GammOnLine forum]
Running rollouts in background  (Bruce+, Apr 2004)  [GammOnLine forum]
Saving rollout results from command-line interface  (Jeremy Bagai+, Apr 2006)  [GammOnLine forum]
Saving rollouts  (Mislav Radica+, May 2006)  [GammOnLine forum]
Setting GnuBG's playing strength  (JP White, Sept 2001) 
Setting skill level  (Jim Segrave, Apr 2004) 
Setting up and saving a rollout  (Albert Silver, Dec 2003)  [GammOnLine forum]
What's GNU?  (Gary Wong, Oct 2001) 
Which player is player 0?  (Neil Kazaross+, Oct 2004)  [GammOnLine forum]

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