[NickRW]

Cascade, on Jul 17 2009, 02:57 AM, said:

NickRW, on Jul 17 2009, 01:07 PM, said:

I've done a lot of simulations of different specific combinations of distributions in both hands.  I came up with 4333 being about a quarter of a point worse than 4432 and about half a point worse than 5332 (and about a point worse than something with a 6 carder) specifically for NT contracts.  A 2 point downgrade is way way over the top.

4333 is worth about a point worse than 4432 for suit contracts with 5332 only very slightly better still.

Nick

Double dummy?

Yes, those were DD results. I've since used what I learnt at the table - I am not dissatisfied with the results - but counting in quarters or whatever isn't going to appeal to many.

Nick

[dellache]

1. Using DD simulations and SD checks, here are the results I came up with facing a 13-15HCP no trump :
- RED, always bid 3NT with 11+, never invite with less (never play 2NT)
- WHITE, always bid 3NT with 12+, usually invite with 11.

2. Downgrading 4333 by 2 points is way too much.
We have very good results downgrading them -1 (relatively to 4432 with no isolated quacks).

3. BTW, it seems that the fate of bad 3NT contacts that involve a 4333 depends more often than not of the strength of the oppos. So I will tend to relatively overbid when playing against not so good defense, or against tired experts.
--
FD
Codesigner of the Spider system.

[cherdanno]

Even a one point downgrade is too much.

[nigel_k]

Simulating two balanced hands of approximately equal strength and no 8 card major fit, I get:

Combined 24 HCP: less than 8 tricks 24.40%, 8 tricks 39.58%, more than 8 tricks 36.02%
Combined 25 HCP: less than 8 tricks 12.41%, 8 tricks 31.94%, more than 8 tricks 55.65%

Bidding 3NT with 24 combined HCP therefore has a gain of 0.5 IMPs per board when vul. To avoid underbidding you have to take into account the times you only lose 3 IMPs because 2NT doesn't make.

Non-vul you lose 0.3 IMPs per board bidding game with 24 HCP but gain 1.5 when holding 25 HCP. So this suggests bidding game any time you have a better than average 24. Plus, they always find the right lead double dummy but not in real life, especially after 1NT-3NT. So a good rule of thumb is probably that 24 HCP is enough for 3NT.

Regarding the 4333 shape, I wouldn't adjust it at all for NT bidding. For example I simulated KJ92 A32 32 KQ32 and KJ92 A32 432 KQ2 opposite a balanced 11 and they came out almost identical. Certainly an extra nine (maybe even an eight) would more than compensate for the difference between 4333 and 4432.

Obviously it's different at pairs because you want a higher chance of making and would like to stay with the field (to the extent you can when playing a 13-15 NT).

[WesleyC]

I did a simulation a while back and the results agree with Nigel_k. The setup was:

- North is 11-19
- South is semi-balanced with enough points to give the partnership a total between 20 and 30.
- 10,000 simulations each for North being 4333, 4432 and 5332.

Double dummy analysis suggested the average number of tricks when North's shape is 4333 is actually slightly HIGHER than when he holds 4432 or 5332. This unexpected results is likely caused by the limitations of double dummy analysis. "Cloud 3NT" contracts (as Kenrexford calls them) are aided by double dummy declarer play and occur more frequently when opener is 4333.

However, the underlying message is clear - 4333 hands should not be significantly devalued for declaring NT. I believe upgrading hands with Aces and interior texture, while downgrading hands with Queens and Jacks is a better way to split the marginal hands when considering a No-Trump invite.

[Apollo81]

cherdanno, on Jul 19 2009, 09:17 AM, said:

Even a one point downgrade is too much.

Agree, I think half a point is about right.

[TimG]

WesleyC, on Jul 22 2009, 01:10 PM, said:

- North is 11-19
- South is semi-balanced with enough points to give the partnership a total between 20 and 30.
- 10,000 simulations each for North being 4333, 4432 and 5332.

Double dummy analysis suggested the average number of tricks when North's shape is 4333 is actually slightly HIGHER than when he holds 4432 or 5332.

A while back, I did something similar (without 5332 hands) and found that two factors where important when counting tricks at NT:

1) the more suits in which there is four-card length in at least one hand the more tricks; and

2) 3-2 and especially 2-2 holdings reduced the number of tricks.

If north is 4=4=3=2, it is better for south to be 3=3=4=3 than 4=3=3=3 because in the former case there are three suits with at least one four-card suit (♠, ♥, ♦) whereas in the latter case there are only two such suits (♠ and ♥).

It was also better to have 4=4=3=2 facing 3=3=3=4 than 3=3=4=3 -- a 3-3 and a 4-2 is better than a 4-3 and a 3-2. 2-2s are even worse than 3-2s.

So, it does not surprise me that 4333 might have a higher value than 4432 or 5332 when facing a semi-balanced hand -- no possible 2-2 suits.

I suspect strongly that if you give south a 4333 13 count and north 1) 4432 13 count or 2) 4333 13 count, on average the 4333+4432 combination will take more tricks at NT than the 4333+4333 combination.

[WesleyC]

TimG, on Jul 22 2009, 01:50 PM, said:

I suspect strongly that if you give south a 4333 13 count and north 1) 4432 13 count or 2) 4333 13 count, on average the 4333+4432 combination will take more tricks at NT than the 4333+4333 combination.

I ran a quick simulation (10000 deals) of exactly the situation you suggest.

With 13 opposite 13 both 4-3-3-3 average (double dummy) tricks was 8.99.
With 13 (4333) opposite 13 (4432) the average total was 9.03.

So you're spot on.

[pooltuna]

mtvesuvius, on Jul 16 2009, 01:46 PM, said:

What are the statistics for 4333 hands, and how much should I downgrade them over 1NT (13-15)?

Axxx AQx Qxx xxx

3NT

AJT Qxx Axx xxxx

2NT if invitational

xxx QJx ATx KTxx

pass

xxx Kxx AJxx Kxxx

Director!!! I have 14 cards [2NT invitational]

How would you treat these hands?

My partner thinks that even at IMPs, we should be downgrading these hands a good 2 points. I disagree, since I think we should be in any games that have a prayer. Something such as Kxx Jxx Kxxx AJx he suggests we should invite. What are your thoughts on this, and how much should we be downgrading here? Or has he just gone mad?

Don't downgrade! the game going point count total is better as a decision process than you are trying to figure out if you should be in game because you don't see your partner's half of the points or his distribution.