Match Equities

Forum Archive : Match Equities

ME Table: Woolsey

From:   Kit Woolsey
Date:   24 May 1994
Subject:   Re: Some interesting takepoints

Whatever else you do with match equity analysis, please don't use Roy
Friedman's tables.  They are just plain wrong.  They are based on the
incredible supposition that, when one player needs a gammon and the other
doesn't (such as at Crawford game with trailer having an even number of
points to go and post-Crawford with trailer having at least 3 points to
go) that 35% of the trailer's wins will be gammons!  Friedman claims to
have rolled out over 3000 games to come up with this result.  This is an
incredible assumption which is far from everybody else's estimate.  My
personal estimate of 21 or 22% of the trailer's wins being gammons is
much more accurate, pretty well agreed upon by most good players, and
confirmed by study of over 1000 matches in Hal Heinrich's data base.  I
have discussed all this in an article I wrote in Inside Backgammon a
couple of years ago.  For the record, below is the match equity table
which I have developed, based upon empirical data from Heinrich's data
base and a computer program I wrote which properly computes the equities
based upon this empirical data.  The numbers on top represent the number
of points the leader has to go; the numbers on the side the number of
points the trailer has to go, and the numbers in the matrix represent the
percentage of time the leader can be expected to win.  When the leader
has 1 point to go, it is assumed that the Crawford game has not yet been

        1       2      3      4       5      6      7

1      50      70     75     83      85     90     91
2      30      50     60     68      75     81     85
3      25      40     50     59      66     71     76
4      17      32     41     50      58     64     70
5      15      25     34     42      50     57     63
6      10      19     29     36      43     50     56
7       9      15     24     30      37     44     50

For example, the leader's advantage at 5 away, 2 away is 75%, not the 72%
that Friedman's tables would have you believe.

Kit Woolsey
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Match Equities

Constructing a match equity table  (Walter Trice, Apr 2000) 
Does it matter which match equity table you use?  (Klaus Evers+, Nov 2005)  [GammOnLine forum]
Does it matter which match equity table you use?  (Achim Mueller+, Dec 2003) 
Does it matter which match equity table you use?  (Chuck Bower+, Sept 2001)  [GammOnLine forum] [Long message]
ME Table: Big Brother  (Peter Fankhauser, July 1996) 
ME Table: Dunstan  (Ian Dunstan+, Aug 2004)  [GammOnLine forum]
ME Table: Escoffery  (David Escoffery, Nov 1991) 
ME Table: Friedman  (Elliott C Winslow, Oct 1991) 
ME Table: Kazaross  (Neil Kazaross, Dec 2003)  [GammOnLine forum]
ME Table: Kazaross-XG2  (neilkaz, Aug 2011) 
ME Table: Rockwell-Kazaross  (Chuck Bower+, June 2010) 
ME Table: Snowie  (Chase, Apr 2002) 
ME Table: Snowie  (Harald Retter, Aug 1998) 
ME Table: Woolsey  (Raccoon, Apr 2006) 
ME Table: Woolsey  (Kit Woolsey, May 1994) 
ME Table: Woolsey  (William R. Tallmadge, Jan 1994) 
ME Table: Zadeh  (Jørn Thyssen, Mar 2004)  [GammOnLine forum]
ME Table: Zorba  (Robert-Jan Veldhuizen+, Dec 2003) 
ME at 1-away/2-away (crawford)  (Fabrice Liardet+, Nov 2007)  [GammOnLine forum]
ME at 1-away/2-away (crawford)  (Ian Shaw+, Apr 2003)  [GammOnLine forum]
Match equities--an alternate view  (Durf Freund, Oct 1994) 
Neil's new numbers  (neilkaz, Aug 2011) 
Neil's numbers  (Kit Woolsey+, Oct 1994) 
On calculating match equity tables  (Neil Kazaross, July 2004)  [GammOnLine forum]
Turner formula  (Gregg Cattanach, Feb 2003) 
Turner formula  (Stephen Turner, June 1994) 
Using a match equity table  (Michael J. Zehr, June 1992) 
Value of free drop  (Neil Kazaross, Oct 2002)  [GammOnLine forum]
Which match equity table is best?  (Martin Krainer+, Oct 2003) 
Which match equity table is best?  (Ian Shaw+, Dec 2001) 
Why use a match equity table?  (Kit Woolsey, Feb 1999) 
Worth memorizing?  (Alef Rosenbaum+, Feb 2003) 

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