[smerriman]

johnu, on 2024-November-15, 22:31, said:

Matchpoints or IMPs? In my simulations, NT was clearly better at matchpoints, but worse at IMPs.

mycroft's statement was about MPs, so I was using that. But agree re IMPs.

Cyberyeti, on 2024-November-15, 13:23, said:

I would invite slam by whatever method I had, likely 4♣ which has the advantage of denying a spade control which means partner doesn't get in any way excited with Qx, KQxxx, KQx, Jxx but nor do we play in 3N-1

jillybean, on 2024-November-15, 20:37, said:

Puppet provides responder with a lot of information about openers shape and may be the start of a slam probe. Perhaps only hands with some slam aspirations should use puppet here?

Suppose after hearing 3♥ you bypass 3NT, and plan to bid slam if partner has 12-13, a spade control, appropriate keycards (2, or 1+Q), and can somehow do that without ever ending in 5♥. A simulation has you still only scoring 38% vs signing off in 3NT, simply because of all of the times you're in 4♥ losing to 3NT.

If you bypass 3NT, then peek at partner's cards and only play slam precisely when it's makeable, that maximum you can achieve is 58%. I don't think any system will come close to that.

If I have a stronger hand I suspect playing 4NT or 6NT will turn out better than Puppet for similar reasons.

[DavidKok]

johnu, on 2024-November-15, 22:23, said:

If not double dummy odds, then what???

In real life, defenders don't make perfect leads, they sometimes make bad/unfortunate opening leads. They may open up a frozen suit, expose partner's queen in a 2 way guess position, fail to lead a suit setting up a trick which allows declarer time to set up 12 tricks, etc. They may get pseudo squeezed, or discard poorly and expose partner to a squeeze.

Are double dummy odds accurate? As a gross evaluation, I think close enough. If the double dummy odds are 40%, and you need 50% to be a reasonable contract, then a reasonable interpretation is that the contract is not favorable. If the double dummy odds are 60%, then a reasonable interpretation is that the contract is favorable. If the double dummy odds are around 50%, then it's a tossup.

Richard Pavlicek did an analysis about the accuracy of double dummy simulations, and for 6 level contracts, the difference in success rates between actual play results and double dummy simulations was around one and a half percent (double dummy better). So not a big difference.

I am very familiar with those results. This is exactly why I specified that this is a case of balanced-opposite-balanced with traditionally insufficient HCP strength. This is an area where DD outperforms single dummy by a large margin. The 1.5 percentage points (not percent) you cite includes 6-suit contracts and is conditional on a dataset where the slam was actually bid at the table. That screens off most of the hands that are comparable to this situation. For 6NT in particular the advantage is 6.97 percentage points in favour of DD (73.48% single dummy versus 80.45% double dummy, though of course most of these digits arent significant), but since this is still conditional on humans bidding the 6NT it is a gross underestimate once we condition on weaker hands, where the contract hinges on a guess more often. This is also reflected in having a double dummy success percentage of well under 80%.

In general I am a fan of using double dummy simulations to gain better insight into bridge. It is a quick and powerful tool, and pretty much the only way to get sufficiently large sample sizes to do statistical analysis. However, it is important to be cautious in interpreting results. Under the exact conditions of this post I think it is naive to rely on double dummy numbers. You ask me "If not double dummy odds, then what???". I think it is better to not insert incorrect numbers, even if we do not have the correct ones.

[Cyberyeti]

smerriman, on 2024-November-16, 00:43, said:

Suppose after hearing 3♥ you bypass 3NT, and plan to bid slam if partner has 12-13, a spade control, appropriate keycards (2, or 1+Q), and can somehow do that without ever ending in 5♥. A simulation has you still only scoring 38% vs signing off in 3NT, simply because of all of the times you're in 4♥ losing to 3NT.

I disagree with this. Remember you're playing odd methods, the field will be in hearts either having passed or opened 1♥ in a strong NT context with partner's hand.

5♥ is not a disaster if 5♥ makes 11 and 3N makes 10 (or it's 12:11). The other issue is that there may be a finesse which you can take trivially in hearts, but opps have a lot of spades or diamonds to cash if it's wrong and you take it in NT.