1. S: 963
H: 9
D: K7654
C: AKQ3
S: AKT2 S: J84
H: K53 H: QJT842
D: AQT2 D: 9
C: 52 C: JT6
S: Q75
H: A76
D: J83
C: 9874
North opened 1
, I overcalled 3
as East and partner bid 3NT to play. Oppo started off with a couple of rounds of clubs but then got bored and switched and partner wound up with an overtrick. You may not agree with my choice of overcall, but give me an extra heart and it makes no difference to the outcome — 4 is substantially the better contract.
2. S: KJ98765
H: 9
D: 42
C: 743
S: A S: 42
H: KJT852 H: Q74
D: Q6 D: KJT983
C: T952 C: AK
S: QT3
H: A63
D: A75
C: QJ86
At our team-mates' table, North opened 3
in first, East passed and South tried 3NT. Not a great success as you can see. 4 has no chance either but it's a lot fewer undertricks.
3. S: 9743
H: AJ98752
D: K
C: 9
S: A8 S: QT52
H: 43 H:
D: A9642 D: QJT5
C: Q652 C: KJ843
S: KJ6
H: KQT6
D: 873
C: AT7
At a friend's table, North opened 3
in first, East passed and South tried 3NT rather than the raise. It worked out fine on a low diamond lead, but could have gone horribly wrong with 4 excellent.Bad luck or bad judgement? Let's give our partners some likely hands for their preempts and simulate how the two strains compare.
On the first hand, with LHO opening 1
and partner overcalling 3, I ran 1000 tests. On 498 of those, both contracts failed or both contracts made. However, on every single one of the remaining 502 deals, 3NT went off with the major game making. Never was 3NT better. In terms of IMPs (and I assumed that we were vulnerable for all tests and never doubled), playing in hearts scores you a whopping 7.4 IMPs/board. The reasoning, I suppose, goes as follows: if partner has good enough hearts to run then it's highly unlikely that he's able to stop the club suit.Next, the spade preempt and again 1000 tests were carried out. This was a lot closer. In fact, the raise to 4
won by only a single case. On 187 occasions the major game was making with 3NT failing, while on 186 the reverse occurred. The rest of the time, both contracts made or both went off. The IMPs score was more favourable to those playing in suit contracts, though, with an average gain of 1.9 IMPs/board. This reflects that, while it's fairly even in terms of purely making your contract, 3NT is likely to go off more and those vulnerable undertricks can add up.And finally, the other heart preempt when we had that four-card support. This time, of the 1000 tests, 40 resulted in a game swing for 3NT, 330 for raising to the heart game, while the other 630 were more neutral. In all, you gain an average of 5.5 IMPs/board by playing in hearts.
Obviously, the oppo may well have a blind lead. On hand 1, a club lead might not be obvious from a lot of North's holdings and 3NT will sneak home. Nevertheless, I think that a figure of 7.4 IMPs/board is pretty convincing, as is 5.5 IMPs/board for hand 3. Hand 2 is much closer.
Generalisations to follow. Some day. If you're lucky.
4 comments:
Interesting post, Michael.
When you set up the simulation - what did you use to set up the preempting hand. I.e. what range, shape etc.? Obviously it occured to me that there might be general rules that you could go by on position and vulnerability of preempt. Your results of the simulation are clear that raising is best (in terms of expected imps which is important) but I wonder if that is consistent across preempting positions.
Chris C
Yes, I should probably have clarified this as it's obviously vastly different if you're opening third at green or second at red. The criteria I used were:
* 3-9 HCPs
* 7 card suit
* 5.5 losers or worse (a better hand would open 4S)
* 2+ points in the suit (so Qxxxxxx or better)
This is actually the same criteria I used when judging an opposition preempt earlier. Of course, when it's my own partner I should be able to make this a lot tighter and adjust for position and vulnerability but I still think it's a good enough indication. For every hand which we deal which you wouldn't have opened or hand which you'd open but we didn't deal, there will be dozens of normal hands such as:
KJ98765
K8
J
932
A987542
Q
J9
953
KJ97642
QJ
JT
T5
AJ97654
42
Q98
2
etc. etc.
If I do some more work on this topic then I'll tighten up our idea of a preempt first.
Hi,
"The reasoning, I suppose, goes as follows: if partner has good enough hearts to run then it's highly unlikely that he's able to stop the club suit."
I don't think that's quite it. The problem with the West hand in the first example is that it's too good. If you bid 3NT you're hoping you have precisely nine tricks to run. But on this hand if the hearts do run you surely have at least ten tricks playing in hearts. So there's just no advantage to playing in NT.
That contrasts with the second hand where it's easy to imagine having four losers playing in hearts even if the hearts run.
Thanks for this blog. I have done some mini-simulations using deal but no double dummy engine so had to go through the results by hand and did far fewer.
The one I remember was caused by a hand where I held a 4144 hand with 10 pts at green. I passed and LHO opened 4h. Partner and RHO passed and I doubled for takeout which partner then passed out. We took them one off for a top since everyone else had played in 4h undoubled. My LHO complained locally about my random bidding but I thought it was a clear action. I ran a simulation of 200 deals where I had takeout double shape and 9-11 points and LHO had a standard 4h opener. It was almost always right at pairs or teams to double. If we didn't have some good escape then frequently 4h failed.
Maybe I'll go and buy GIB to do this properly as you do.
By the way it would be useful to create a library of deal definitions.
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