Jacoby 2NT Revisited
A Match Point Strategy
I am concerned the the traditional responses to a Jacoby 2NT inquiry foreclose the possibility of playing in 3NT at MatchPoints when Opener has a balanced minimum. I let Bridge Baron's deal generator run overnight. I now have 982 Jacoby 2NT deals to play with. Unfortunately, the evaluation of contract performance (although automated) can not be done in a batch mode with Bridge Baron. So, I evaluated a bunch of hands individually.
My initial parameters were for Opener to have a hand suitable for a One Spade opening, with Spade suit of at least 5 cards and no singletons or voids. Responder had a hand suitable for a Jacoby 2NT reponse, with at least 4 spades, and no singletons or voids. Responder was also prevented from having a side suit of 5 cards or longer.
Through 52 hands meeting these parameters, NT was a superior contract to Spades by the result of 28-22-2. This would indicate that a Match Point strategy which left open the possibility of a contract in NT after a Jacoby 2NT response would be advantageous.
On the other hand, due to the fact that 8 hands made game at Spades which were set at 3NT (versus 2 hands which made at 3NT and set at 4S), it would not be prudent to inquire about NT when playing at IMPs.
Interestingly, there were 8 hands which made slam at NT but not at Spades, versus 2 hands which made slam at Spades but not NT. As a general rule, as the hands become stronger, it became more advantageous to play at NT with these shapes. It would seem that hands which meet these parameters and which go to slam should be bid at 6NT rather than 6S regardless of the method of scoring.
An additional parameter could be added that each hand have hcp in at least two of the three side suits. This would eliminate 7 of the 52 hands, and adjust the score to 25-18-2 in favor of NT. This parameter also eliminates two of the 8 costly hands which made game at spades but not NT, but none of the hands which made game at NT but not spades.
As an aside, the number of spades held by repsonder did not seem to be a significant factor. Hands where responder held 5 or 6 card spade support seemed to play as well at NT as Spades provided the above parameters were met. Nonetheless, I'd still be inclined to play these at Spades over NT.
I suggest that we stick to our structure of;
-New Suit at 3 level: shortness, minimum
-Bid Suit at 3 level: balanced, minimum (except 1H-2NT-3S which is ambiguous as to strength)
-3NT: balanced maximum
-New Suit at the 4 level: shortness, maximum
but add the following treatment:
If Responder has a hand which meets the NT parameters, he bids 3NT over a 3-Agreed Major reply to the Jacoby 2NT. If Opener has a hand which has hcp in at least two of the side suits and no five card side suit, he will Pass, else correct to 4 of the agreed major.
If Responder has a hand which meets the NT parameters, but does not wish to inquire about Slam after a 3NT follow-up by opener, he may Pass the 3NT follow-up.
I realize that there is a chance that Opener does not meet the "hcp in at least two side suits parameter", however, that chance is diminished given that he has shown a maximum. Also, the %s were still in favor of 3NT even without this parameter, so I'm inclined to take this risk at MatchPoints.