[whereagles]

lmilne, on Apr 30 2010, 01:12 AM, said:

Jlall, on Apr 29 2010, 09:16 AM, said:

It's like saying if someone bets the river it is never right to call if raise and fold are both available options.

jlall, master of analogy

I hate analogies because it usually boils dow to taking something out of context to make a point on a completely different situation. It's manipulative. One should be able to argue on one's own.

[whereagles]

pooltuna, on Apr 29 2010, 02:02 PM, said:

bidding again is anti-partnership. When you make partner captain it is rarely correct to bid again

That would be true if you're playing that a michaels always shows a 5-5. When it can be some assorted defensive 5-4 junk, it's not so clear. You'll have to take full blame if 5♥ turns out wrong, but it can EASILY be the right bid and you win by making those.

Actually, I think it's even debatable that pard is totally the captain here. I agree he's captain with respect to suit. As to level, I wouldn't be so sure. Especially when your ODR is a superb as this.

[helene_t]

whereagles, on Apr 30 2010, 01:00 PM, said:

lmilne, on Apr 30 2010, 01:12 AM, said:

Jlall, on Apr 29 2010, 09:16 AM, said:

It's like saying if someone bets the river it is never right to call if raise and fold are both available options.

jlall, master of analogy

I hate analogies because it usually boils dow to taking something out of context to make a point on a completely different situation. It's manipulative. One should be able to argue on one's own.

Yeah but in this case it's a good analogy. If you know poker terminology it is easy to follow the reasoning in the (simpler) poker case, and then it's easy to see why the same argument applies to bidding decisions in bridge.

Not that it is so difficult to argue the point without an analogy. Phasing three alternatives A, B and C, where you know that either A or C would be optimal if you had full information, it is easy to imagine that B, the sure second-best bet, is the optimal choice in the absence of full information.

[cherdanno]

Mbodell in your long post you make a much more elaborate analysis of the payout matrix at poker than the one at bridge - and the one at bridge is just waaay too simplistic.

Mbodell, on Apr 30 2010, 04:36 AM, said:

Even comparing just one to the other, if you think pass is better than X you are saying you think they are more than 50% likely to make their contract.  If you think pass is better than 5♥ you are saying that more than 50% of the times either both contracts are down OR (5♣ makes and 5♥ is down 3+ tricks).

If you think they have a 55% chance to make, and that you will be down 2 in 5♥, and that there will be some -150/-130 or -100 or -200 scores in the field, then pass beats both double and 5H.

Anyway, there is a good reason to believe 5C will be making - partner didn't double and he knows our type of hand very well. There is also a good reason to believe 5H won't be a good sacrifice - partner didn't bid it and he knows our hand very well.

[jdonn]

The whole analysis is a waste. We promised a specific type of hand and partner did not. Therefore it is his decision to make. We could overrule his decision if we had anything but exactly what we promised, but that is what we have, so....

[bluecalm]

Quote

In this case, unlike poker, the only place where pass beats both X and 5♥ is if ♣ make at least 5 and ♥ is down at least 3. Maybe it is the case that both 5♣ makes at least 11 tricks and 5♥X makes no more than 8 tricks at least 50% of the time, but if not, then it is hard for pass to be the right bid (even if figuring out what is the right bid between X and 5♥ is hard).

JLall's analogy was right.
Your analysis assumes you know your opponents "cards" so if your hand is better you should raise (because maybe he will call with his weaker hand) and if your hand is worse you should fold (obviously).

Back to bridge terms, you assume that you are either down 3 in 5♥dbl or you are not and that they are making or not. Obviously you don't know that when making your decision.
Very simple example is this:
-they are always making
-you are down 3 in 40% of cases
-you are down 2 in 60% of cases.

Let's compute EV of passing versus going to 5♥ doubled.

in 40% of cases 5♥ loses 5imps (800 - 620 = 180 = 5imps)
in 60% of cases 5♥ wins 3imps (620 - 500 = 120 = 3imps)

So EV of going to 5♥ is -40% * 5imps + 60% * 3imps = -0.2imps.

So 5♥ is correct most of the time but passing is right action (and if they are sometimes losing 4♠ the EV difference will be much bigger)
This example is very simplistic but good enough to discard your analysis I think.

[gwnn]

you gotta be a little more careful, it's matchpoints.

[bluecalm]

Quote

you gotta be a little more careful, it's matchpoints.

Yeah right. It's easy to construct similar example for matchpoints though.
For example it's enough if going from +100 to +200 will be worth 30% (from 70% to 100%) and going from - 620 to -790 will be worth 50% (from say 50% to 0%)

[aguahombre]

Actually -950 or 1400 (if xx), but same zero.

Unless they only make 5, then it is the same zero, too.

[Jlall]

bluecalm, on Apr 30 2010, 10:30 AM, said:

Quote

In this case, unlike poker, the only place where pass beats both X and 5♥ is if ♣ make at least 5 and ♥ is down at least 3. Maybe it is the case that both 5♣ makes at least 11 tricks and 5♥X makes no more than 8 tricks at least 50% of the time, but if not, then it is hard for pass to be the right bid (even if figuring out what is the right bid between X and 5♥ is hard).

JLall's analogy was right.
Your analysis assumes you know your opponents "cards" so if your hand is better you should raise (because maybe he will call with his weaker hand) and if your hand is worse you should fold (obviously).

Back to bridge terms, you assume that you are either down 3 in 5♥dbl or you are not and that they are making or not. Obviously you don't know that when making your decision.
Very simple example is this:
-they are always making
-you are down 3 in 40% of cases
-you are down 2 in 60% of cases.

Let's compute EV of passing versus going to 5♥ doubled.

in 40% of cases 5♥ loses 5imps (800 - 620 = 180 = 5imps)
in 60% of cases 5♥ wins 3imps (620 - 500 = 120 = 3imps)

So EV of going to 5♥ is -40% * 5imps + 60% * 3imps = -0.2imps.

So 5♥ is correct most of the time but passing is right action (and if they are sometimes losing 4♠ the EV difference will be much bigger)
This example is very simplistic but good enough to discard your analysis I think.

There was a thread once where I made a post similar to this. At MP it's a little more complicated, but the same point applies.

Mbodell:

There are going to be a ton of decisions where you're not sure who has what, and what their chances are of making or what you could have made. In those times of uncertainty, it is my view that it is very wrong to force yourself to commit one way or the other to "they are making too often" or "they are going down too often."

Not only can you come up with a (albeit contrived) mathematical model where the percentages of everything break down such that it's right to pass, it just seems like common sense and "bridge" to me to accept that you don't have perfect information, and on this hand you have bits and pieces of defense but not enough to warrant making a strong view about your chances. The times when it's best to pass are the times when things are most uncertain.

This hand is a good example. Are they making? Who knows, it was a pretty random auction, our stiff queen might add a trump trick somewhere, our SK might be a trick, and we have no idea what their hands look like. Saving is a complete gamble to me (that would be my choice over X if I had to pick one).