Czuch Chuckers: Up 6-0 in a 7 point match, you will be playing the Crawford game where no double is allowed (http://brainking.com/en/GameRules?tp=23). Assuming that the trailer wins the Crawford game, it will be 6-1. Here's where it gets tricky.

Post-Crawford doubling strategy

Leader's strategy:

As the leader, you must assume that the trailer will double at every opportunity. Therefore, the trailer needs only three wins to take the match. When you are leading by an odd number of points, you have one "free drop." This means that if you drop a double at 6-1 making the score 6-2, the trailer must still win three games to win the match.

You should not drop a post-Crawford double when you are leading the current game or when the game is even. You probably should drop the first post-Crawford double that occurs when you are behind in the game (you may not get another opportunity).

You should not drop a post-Crawford double when you are leading by an even number of points, even though you are behind in the game, unless you think you are going to be gammoned. For example, suppose the score is 6-2 and your opponent doubles. You are significantly behind in the pip count but you don't expect to be gammoned. If you drop, the score will be 6-3 and the opponent will need only two more (doubled) wins to win the match. If you take and lose, the score will be 6-4 and the opponent will still need two more wins for the match. In other words, you are no worse off after taking than after dropping, and by taking you have a chance to come back and win the game and match.

Trailer's strategy:

If you are trailing by an odd number of points, you should double as soon as possible. If you wait until after you are ahead in the game, your opponent will use his free drop and you will have wasted a win. If you are trailing by an even number of points, many players will wait until an opportune moment to double. For example, you may double at a time when a good roll will put you in position to win a gammon; the opponent may drop out of fear of losing 4 points, and you will have advanced one win closer to winning the match. Or you may wait to double until you have taken a significant lead in the game, hoping that your opponent will make a mistake and drop.