Source: acblunit391.org

Amit Chakrabarti is a Bridge Theorist with a particular interest in high level bidding systems development. 

Marshall Miles, an ACBL Hall of Fame member, stresses this point in the introduction of his excellent book “Inferences at Bridge” with the following example.

What action do you take holding: spade 83 heart A diamond 653 club AKQ9754

LHO Partner RHO You
3spade Pass Pass ?

and opponents are vulnerable and you are not.

Here I quote from Marshall Miles’ book: “At least nine players out of ten would bid 4club.

They would do so either because they lack imagination or because they are unwilling to gamble, even when the odds are in their favor. Think about it. At favorable vulnerability would LHO open 3spade with a solid spde suit? No; he could miss a game since with a singleton or void in spades, his partner would pass holding 15 or 16 high card points (hcp). ….. Then what about RHO? Would he pass with spadeKxx or spadeAxx ? No again.

Do you see where I am going? I think the odds favor a 3NT bid.” The real reason I think most players would not bid 3NT with this hand is that they are afraid of the post-mortem. If the opponents take the first 7 tricks, everyone will hear about how you thought of your doubleton 8 as a stopper.

Yes, there are some cruel bridge players in this world who, instead of protecting their partner’s emotional well-being, would rather tell everyone in the room how “dumb” their partner is.

But as I always said, post-mortems are not where battles are won.