[Trinidad]

kenrexford, on Jun 5 2009, 12:53 PM, said:

The trouble was whether 5♦ as a final contract was maniac overbidding, maniac underbidding, random nonsense, or completely legitimate for the actual deal.

I guessed wildly wrong.

In that position, I wouldn't do any guessing. I already have a 3 in 4 chance for a top by just passing! (Yes, I know, assuming that all four possibilities are equally likely, which they aren't.)

By doubling, you give the opponents a chance to compensate for maniac underbidding (by redoubling) or to correct the random nonsense to a better contract. You could convert an 85% score into a 0 or an average. If the contract is completely legitimate you will convert a 40% board into a 0% board. On top of that, there is the additional possibility that they are supposed to be in 3NT, when they have 10 tricks or they should have doubled 4♥. In either of these cases, part of the field will be there and you will turn a good board into a zero.

And what can your double win? Only if the opps were guilty of maniac overbidding, you will convert an 85% board to a 100% board. Congratulations.

Rik