Page "Stayman convention" Paragraph 21

Partnerships who had not used Stayman but choose to adopt Stayman will need to adjust their use of normal level 2 responses after a 1 NT opening, because the availability of this convention changes the nature of what had been normal 1 NT responses.

When the notrump bidder's partner does not invoke Stayman but instead calls 2 Hearts or 2 Spades, it is a sign of relative weakness ( since if responder held 8 HCP or more, he'd have invoked Stayman ).

These bids are commonly referred to as " drop dead bids ", as the opening NT bidder is requested to withdraw from the auction.

If opener has maximum values, a fit, and strong support, he may raise to level 3, but under no circumstances may he take any other action.

This provides the partnership with an advantage that the non-Stayman partnership doesn't enjoy.

For example, a responder may have no honors at all ; that is, a total of zero HCP.

His partner is likely to be set if he passes.

A non-Stayman responder would have to pass, because to bid would provoke a rebid.

But a Stayman responder can respond to his partner's 1 NT opening at level 2 if he has a 6 card non-club suit.

The responder with 3 HCP and a singleton can make a similar call with a 5 card non-club suit.

This gives the partnership a better than even chance of success in making the contract, whereas without a response ( and without Stayman ), the contract would likely be set.