Backgammon: Odds or MCV?

Look at the backgammon position below, it is a money game (or early in a match) and White is on roll. Should White double? If White doubles, should Black take?

The doubling cube is often a complex consideration, and the above position is not a simple one. The correct answer is that White should double and Black should take.

But don’t feel bad if you got it wrong…many very fine players will not think this is a double, but I do believe most good players would get the take correctly.

Why Double?

At first glance, this backgammon position does not look like a double. The race is even; Black has only one checker back and White has two back. And Black has only one blot to attack on the entire board.

The key consideration in this, and in most other doubling decisions, is to try to determine the “Most Common Variation,” or MCV. By that I mean, what is most likely to occur in the next one, or two, or even three rolls? In this case, If White simply has a lot of excellent rolls and likely sequences for the next couple of rolls so that if he does not double, now he would “lose his market.” That means that if he does roll well, and then doubles, he will get a drop.

Now, it’s not such a bad thing to get a drop…it means you win a point. But it’s not so hot to win a point if you have a very good chance to win 2 points, or maybe 4 points if you win a gammon.

What's the Next Roll?

Take a good look again at White’s position and think about his next roll. If he rolls any 6 or 9 he should hit Black. Now, there is some risk getting hit back, but if he gets hit back it’s not the end of the game and White still has a decent position. But the odds are pretty good that he won’t get hit back, and in that case has a great chance to contain Black’s checker and maybe even win a gammon.

What if White doesn’t rolls a 6 or 9? Black is still behind a 5-prime and can only get out with a 5, and even then, unless it’s double-5, White gets a shot at that checker. So if White doesn’t roll a 6 and Black doesn’t roll a 5, it’s also very likely that on the next roll White will have even more checkers in place to attack Black’s checker.

Backgammon is not all about Odds

So again, the MCV here is that White attacks Black within the next roll or two and gets to a very, very strong position. Yes, sometimes it will not work and White will be sorry he doubled, and he would lose 2 points instead of 1 if he hadn’t doubled. But backgammon is all about odds, and the odds here favor White enough that he should be happy to play for twice as many points and happy to take some chances because of the possibility of greater rewards.

For your reference, below is Snowie’s evaluation of this cube. It shows that White does win this game 64% of the time, and 23% of the time those will be gammons. That’s more than enough to want to double the stakes.
snowie evaluation