[mikeh]

jtfanclub, on Mar 20 2007, 09:48 PM, said:

kenberg, on Mar 20 2007, 08:54 PM, said:

I'll venture a guess that if 4S can be beaten it will be by taking one diamond, one club, and two hearts.

I'd put even money that partner has a spade trick. We have a singleton, and they're certainly sititng in the right place.

I'll take you on! I ran a quick simulation of 50 deals. I excluded 3 that didn't look as if anyone would duplicate the bidding (1 held a defensive trick but had 'overcalled' on K8xxx of ♦s, which seemed unlikely, the other two held no defensive trick in trump) and the results were 15 hands on which partner held 1 or (in a couple of cases) 2 trump tricks and 32 in which he held none.

I ran it too quickly to analyze whether the save was a winning decision, and I suspect that more careful analysis would have excluded some of the 4♠ calls, but those exclusions would not have greatly changed the frequency of holding a defensive trump trick.

[jtfanclub]

mikeh, on Mar 21 2007, 03:31 PM, said:

I'll take you on! I ran a quick simulation of 50 deals. I excluded 3 that didn't look as if anyone would duplicate the bidding (1 held a defensive trick but had 'overcalled' on K8xxx of ♦s, which seemed unlikely, the other two held no defensive trick in trump) and the results were 15 hands on which partner held 1 or (in a couple of cases) 2 trump tricks and 32 in which he held none.

Really! I stand corrected.

Out of curiousity, what did you use for the range of the 2♦ bid?

[mikeh]

jtfanclub, on Mar 21 2007, 03:38 PM, said:

mikeh, on Mar 21 2007, 03:31 PM, said:

I'll take you on! I ran a quick simulation of 50 deals. I excluded 3 that didn't look as if anyone would duplicate the bidding (1 held a defensive trick but had 'overcalled' on K8xxx of ♦s, which seemed unlikely, the other two held no defensive trick in trump) and the results were 15 hands on which partner held 1 or (in a couple of cases) 2 trump tricks and 32 in which he held none.

Really! I stand corrected.

Out of curiousity, what did you use for the range of the 2♦ bid?

The constraints were:

opener: 11-20 hcp, 5+♠
overcaller 10-18 hcp, 5+♦s, no more than 4 cards in any one side suit
responder 3-9 hcp, 5+♠s

Now, one can obviously construct hands outside of these constraints that some percentage of us would bid on, but I wanted a quick and dirty sample. As it was, some hands were clearly outside what I think most would require, and I suspect that several more would be criticized to some degree. But, given that I got 50 hands to work with, and the margin was more than 2-1 against partner holding a trump trick, I'd say that the implications are clear.

Now, if we allow 4♠ calls on 4 card support (and there are some rare hand types that would, in my view, allow this.... QJxx xx x KQxxxx is one such hand), then I suspect that the odds would get closer to 50%, but not by enough to make me reconsider my bet: after all, the great majority of weak 5 card fits will blast 4♠ while only a small minority of 4 card fits would.

[jtfanclub]

I see. I guess I'm more used to people bidding 4♠ with only 4 in IMPs, especially if they have a ruffing value. Perhaps that's just where I hang out. Also, 4 card support is far more common than 5 card support, so even if a smaller % of 4 card supports go straight to 4, that doesn't mean that he's more likely to have 5 card support than 4.

[cherdano]

I would agree that 4-card support is not uncommon for the 4♠ bid.

[jtfanclub]

cherdano, on Mar 21 2007, 09:00 PM, said:

I would agree that 4-card support is not uncommon for the 4♠ bid.

Sorry to re-reply so quickly...

There's an additional factor here. If the 4♠ bid is based on 4 card support, then I think it makes 10-12 hcp unlikely for partner. If partner has 5 diamonds, 3 spades, and 10-12 hcp, he really shouldn't be bidding...2♦ isn't going to slow the opponents down much, he's likely to be on lead, it helps them play the hand, etc. etc. If partner has 6 diamonds and 3 spades (and 10-12 hcp), if he's going to bid anything, he should say 3♦, which I like and I have been assured by people in another thread is pretty normal when partner is a passed hand.

So I guess it comes down to, if the 4♠ bid is almost always 5 spades, then 5♦ is the right call. But if the 4♠ bid is just 4+ spades, are you sure you want to take that bet?

Me, this thread has convinced me to do it with 4 card support and some shape. I mean, you shouldn't be waiting for "100%" before bidding game vulnerable in IMPs. Even 40% is good enough. And who knows, maybe the opponents will be kind enough to bid 5♦.