All or nothing?

[gwnn]

Many a time I find myself at the crossroads...

 

MP scoring, I'm defending, my lead, like trick 2 or 3...

 

I see I have (or we have, if I see my pd's top tricks) the tricks needed to keep declarer to "="... But can we beat him? Of course, we risk overtricks too...

 

Can you give me any general-ish piece of advice on what to do... I mean, yea, I know the theory... We should aim to maximize our trick expectancy, but in defense it's far from obvious many times. The question is basically: can you mathematically determine (even roughly) whether beating it, as opposed to taking what's ours, will give us more MP's? Or is it just a matter of feeling? Or is feeling a sort of experts' intrinsic math engine working?

 

(cashing out is not just the issue here, I know, cause sometimes we have almost nothing to cash, but we just play it cool and leave declarer to give us our sure tricks)

 

Hm... This was a confused post I guess, but I hope I managed to explain myself, at least approximately. Any thoughts will be very appreciated!

[awm]

Of course it's situational, but one thing to do is try to evaluate how normal the contract is. If the contract is unusual you generally need to beat it -- if your opponents are the only pair in game then if they make you'll get a zero regardless of whether you hold down the overtrick. If your opponents are the only pair to stop just short of game, then you'll always beat the pairs defending game making, so you may as well go all-out for the set and try to tie some of the pairs who set the game. If the contract seems very normal it's often a good result to hold them to just making (although again it always depends on the odds of setting).

[pbleighton]

"Of course it's situational, but one thing to do is try to evaluate how normal the contract is. If the contract is unusual you generally need to beat it -- if your opponents are the only pair in game then if they make you'll get a zero regardless of whether you hold down the overtrick."

Agree.

 

"If your opponents are the only pair to stop just short of game, then you'll always beat the pairs defending game making, so you may as well go all-out for the set and try to tie some of the pairs who set the game."

For me at least, usually hard to tell when this happens

 

"If the contract seems very normal it's often a good result to hold them to just making (although again it always depends on the odds of setting). "

I think you may be saying play normal defense, don't risk much, try to get what's coming to you. If so, I agree.

 

Peter

[brianshark]

I saw a statistic once, it's in my MP defense book (by Jim Priebe I think). It basically gives you a run-down of where your MPs are expected to come from in a typical session.

 

To get right to the point, he said that, on average, in a typical MP session (~24 bds => ~4% of the session's MPs per board):

 

- Each overtrick is worth 1% of the MPs for the session

- Each set is worth 2%

 

That would suggest that the setting trick is worth twice as the trick that prevents an overtrick. So if you can safety play for = but try for -1 risking +1 with odds of 50-50, then you should try set the contract. In fact, you should try if the odds are as low as 33% but any lower, just cash out and play for the =.

 

Having said that, this only applies to fairly 'normal' contracts. The analysis above (which is also mentioned in the book) about the 'normality' of a contract supercedes it I think. So if opps bid a pushy 3NT where 3/4 of the field will only be in 1NT/2NT, a set should be 3% and an overtrick only half a percent now or something like that.