[mike777]

3NT vs 4 of a major

With less than perfect information what goes into your decision?

[mikeh]

Shape, obviously. That’s by far the most important factor.

Assuming we’re discussing 4=4 or 5=3 fits (the odds of a 5=4 or 6=3 fit belonging in 3N, and being diagnosable as such are not zero but are, imo, lower than with an eight card fit). Also assuming silent opps.

Texture in the trump suit. Kxxx opposite Jxxx and you could lose three trump tricks even on a 3-2 break.

Overall hcp….to choose 3N over 4 M it’s nice to think your side has at least 26 and preferably 28 or more hcp.

Form of scoring.

There are other factors but these are the ones I’m most conscious of at the table. And other factors are close to intangible. Such as counting tricks

Here’s a simple example of counting tricks from a recent club game. Red v white you hold KJ9 K10xx KJx KJx

Partner deals and opens 3S…partner will have a decent suit and is not hyper aggressive in this seat at these colours.

4S goes down on normal defence, but 3N is impregnable as the cards lay and I think it clear to bid 3N. Partner won’t hold AQxxxxx and a side Ace…that’s a 1S bid. And he’s odds on, in first seat unfavourable, to hold AQxxxxx, given your holding.

[steve2005]

Read Matchpoints by Kit Woolsey