[mikl_plkcc]

As title. I would like the generic principle in both MPs and IMPs, taking consideration of vulnerability as well.

A hopeless contract can be something like a 4♥ with 4 losers which can't be disposed if the opponents can find their best line of play.

[mw64ahw]

a) Don't over-bid with/without competition
b) If the auction follows a logical progression then you won't be alone in 4♥

[awm]

Usually the answer is “take the most tricks you can.” Hopefully you will have some company in the hopeless contract.

The other option is to look for a way opponents could make a defensive mistake and play for that. Deceptive plays like this could be a whole thread though, and might be a rather advanced topic for this forum.

[P_Marlowe]

At IMPs, if you are 1 trick short in a game contract, try to go for a defensive mistake.
At MP, especially if you are red, cut down your loosers, ..., this also a good idea at IMPs in a partial.
In the end, this is a comparison between what do you risk vs. what do you gain.

[jillybean]

Minimise the damage, take as many tricks as you can. Put it out of your mind and move onto the next board.
Take the time after the game to review the board.

[shyams]

deleted

[mikl_plkcc]

In a field of varying ability, especially in a competitive auction, we have no idea where other tables will be. There are a lot of situations when we judge that we have enough strength to bid to the 3-level, but the opponents bid over us at that. We will then be tempted to bid game just for the chance that it will make, as we are never going to double the opponents' partscore into game in IMP scoring unless we hold 5 sure tricks without any bad breaks; if then they bid over our game contract I can then serve a penalty double over them.

There has been multiple situations when the opponents stopped voluntarily at the 2-level with a fit and I balanced them to 4-level doubled.

Also depending on which club I play, if I play in some other clubs with Matchpoint scoring and Acol field with weak NT, my strong and 5 system is already, by definition, an anti-field system (similarly when I play in my home club where strong and 5 is the norm, we have been outcompeted by an Acol pair where their weak 1NT opening shuts off our contract as well).

[akwoo]

Kit Woolsey wrote a whole book about these kinds of calculations at matchpoints.

For IMPs, you're judging how good your opponents are on the fly. The odds are the IMP odds, and you have to compare the IMP odds to the odds opponents will misdefend.

[mycroft]

The nice part about IMP pairs is that the calculations are much closer to field-independent.

If you are in 4♥:

• there are only 9 tricks. You're down 140+50/100 to those in 3 (lose 5 or 6 IMPs), and even with those in 4.
  
• it makes 10 tricks. You're up 620/420-170 to those in 3 (win 6 or 10 IMPs), and even with those in 4.
  
• it makes 10 tricks on an unusual and dangerous line the people in 3 won't take. You're again, +6/10 to those in 3, and are +10/12 to those in 4 that take the normal line.
  
• it makes 9 tricks on the normal line, and the dangerous one doesn't work, and makes only 8. You're now -6 or -8 to those in 3, and -2 or -3 to those in 4 that take the normal line.

So, by taking the dangerous line, you're risking 1 or two IMPs more against the players who stopped in 3, and 2 or 3 imps to those in 4 that take the safe line. When it works, though, you are 11 or 14 up against the players who stopped in 3, and 10 or 12 up against the players who take the safe line in 4.

Therefore, basically, if the dangerous line is 5-1 against NV, or 6-1 against Vul, in the long run it's worth it to try, pretty much independent of how much company you have. (similar numbers apply to those who let the opponents play 3 or 4 diamonds, say; I haven't worked out the numbers, but I've shown you how).

That basically maps with the standard IMP strategy line of "risk an extra downtrick (or two!) to make your contract."

At MPs, it is, as you say, much harder, and as akwoo says, Kit wrote a 300 page book basically running the numbers on hundreds of scenarios.

This is one of the reasons why a) I'm surprised we play MP pairs in the novice field, and b) matchpoints is such a great game - "but it's not Bridge".