Joined: 17 Aug 2006
| Post subject: How Match Equity Works in Real Situations by Phil Simborg
|Playing matches is far more complicated than playing games for straight points, for one point, or for money. The reason is that the scre often complicated doubling cube decisions. Take the position below which came up in one of my matches recently.
Black is winning 3-1 in a match to 5 and is on roll. Should Black double? Should White take or drop if Black doubles?
As you can see from the Snowie evaluation below, Black should not double. If white is doubled, he should take the cube and then redouble immediately so that whoever wins the game wins the match. This is all about score.
There are many reasons why Black should not double. First, if he just plays on and things go very well, he might win a gammon which wins the match for him. If he plays on and things go well and he simply wins a single game, then he goes ahead 4-1 in the match. At 4-1 Crawford he is in a very strong position--in fact, the latest Match Equity Table says he is 81% favorite to win the match. The third reason not to double is that white has a pretty well-timed back game, and as a result, he wins this game about 35% of the time. If he doesn't double and just loses 1 point, it doesn't hurt too much. But if he doubles, and White immediately redoubles, and then he loses 4 points, he has lost the match as a result.
This last point is second-nature to top players, but many beginner and even intermediate players forget this. If Black doubles the cube to 2 and wins the game, he wins the match. If White takes the 2 cube and wins the game, he does not win the match. So White should redouble immediately so that whoever wins the game wins the match.
Now, let's look at this position from white's standpoint. If offered a double in this position he has two choices: he can drop, and the score goes to 4-1 Crawford, or he can take, recube, and whoever wins the game wins the match.
So if he drops, he is 19%. The question is, does he win this game more than 19%? If he does, then he should take, and if he does not, he should drop. As you can see from the Snowie evaluation, he wins 35% of the time, so it's about twice as good to take and recube as it would be to drop.
Therefore, a good player must be able to estimate games and weigh the win/loss and gammon risks against the match equity for all variations.
If you would like a copy of the latest match equity table, you can email me at firstname.lastname@example.org and I'll send it to you.