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I need some help with numbers/stats

#21 User is offline   akwoo 

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Posted 2026-May-22, 16:46

View Postjillybean, on 2026-May-22, 06:07, said:

Thanks, this is the general approach, some are interested in more detail
What are your rules for #2
#3 hopefully partner did make some other bid as we are playing a f1nt


Rules for #2:

3N and 4M are to play, both based on length rather than strength.

2N and 3M are strongly invitational; 3M with a 6 card suit and 2N without.

3lower is game forcing (as is 1H-1N-2S), supposedly a real suit. You may have to lie about 'real suit' if you want to game force on strength but don't have a second suit. (I prefer to put all my lying in 3C, but that requires further artificial sequences.)

2M promises 6. 2lower supposedly promises 4. If you have 6-4 or better, rebid 2M with an absolute minimum and 2lower with a little more.

This leaves all the not-highly-invitational hands that have 5 in the major and no lower 4 card suit. You should lie at the 2 level in your longest minor, clubs if equal. (It's possible to put all the lying into 2C, but that requires further artificial sequences.)
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#22 User is offline   jillybean 

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Posted 2026-May-22, 17:27

View Postpescetom, on 2026-May-22, 15:44, said:

You can also be playing 2/1 game forcing but 1NT semi-forcing, like most of Europe and a good number of top level pairs.
In which case 1NT will rarely or never have 3=card support.
There are also other ways of revealing a weak 3=card support, such as going through 1M-2♦ in a 2/1 context.

So 2♦ is not GF?
"And no matter what methods you play, it is essential, for anyone aspiring to learn to be a good player, to learn the importance of bidding shape properly. MikeH
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#23 User is offline   thepossum 

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Posted 2026-May-22, 21:11

Apologies. I am sure nobody is interested inthe following numbers but I do not have the enerrgy to summarise

I was using Beling's bdeal with 10,000 hands and tried to cover South opening 1M in 1st or 2nd seat and West not overcalling, prepempting or doubling and North having a "forcing" 1NT hand

Spoiler


Is David Kok on holidays :)
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#24 User is offline   pescetom 

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Posted 2026-May-23, 01:29

 jillybean, on 2026-May-22, 17:27, said:

So 2♦ is not GF?

It is when it is not weak :)

It asks Opener to rebid the major, which Responder will pass if weak.
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#25 User is offline   jillybean 

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Posted 2026-May-23, 06:19

View Postpescetom, on 2026-May-23, 01:29, said:

It is when it is not weak :)

It asks Opener to rebid the major, which Responder will pass if weak.

Ok, so you are not agreeing a diamond fit until the 4 level to allow for the semi forcing 1nt.
I haven’t played sf, and don’t understand the benefits.
"And no matter what methods you play, it is essential, for anyone aspiring to learn to be a good player, to learn the importance of bidding shape properly. MikeH
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#26 User is offline   DavidKok 

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Posted Yesterday, 08:54

It depends on your assumptions and system. I've taken the liberty of using my own system, in which a 1NT response is semiforcing and denies a spade fit. Conditioning on a 1♠ opening by partner, a pass by RHO (so no double or overcall) and no game force, no fit and no intermediate jump shift by responder I get the following distribution of club length, simulating 100,000 occurences of this auction:
Spoiler


The distribution of diamonds is identical (except for variance due to the Monte Carlo nature of the simulation). The number of hearts is slightly higher, because I overcall 2♥ more easily than 2m over a 1♠ opening so the negative inference of the pass places more hearts with responder on average.

View Postmikeh, on 2026-May-21, 09:36, said:

The most likely, by far, is 3 clubs. Second probably 4 clubs, third 2 and fourth 5.
In particular, while this is close it is not quite in agreement with my simulations.

If I include weak spade raises, say in the 5-8 hcp range, the frequencies shift. Here's the clubs distribution again with that assumption:
Spoiler


Including the invitational range instead (so that the direct raise is 6-9, and 10-11 goes through 1NT) shifts it less from my baseline, for the people not playing Maas:
Spoiler


View Postthepossum, on 2026-May-21, 20:45, said:

We are talking a serious sim here. I am sure there must be one somewhere :)
The above simulations take between 5.7 seconds (fastest run) and 8.6 seconds (slowest run) each.

View Postpescetom, on 2026-May-22, 15:44, said:

You can also be playing 2/1 game forcing but 1NT semi-forcing, like most of Europe and a good number of top level pairs.
In which case 1NT will rarely or never have 3=card support.
I have seen people define 'semiforcing' in multiple different ways, and some people tie it to the presence of 3-card raises in the 1NT (and prefer to call it 'not forcing', regardless of range, if the response systemically denies 3-card support). Personally I was taught that we need to refer to a not forcing 1NT response in 2/1 as 'semiforcing' regardless of the potential presence of raises, to inform the opponents of the approximate 6-11 hcp range rather than the 'standard' 6-9 range.

View Postjillybean, on 2026-May-23, 06:19, said:

I haven’t played sf, and don’t understand the benefits.
I do not play a two-way 2♦ gadget. Still I prefer the semiforcing 1NT. A major benefit is that opener's 2m rebids promise four cards in the suit, enabling better hand evaluation by responder their second round and improving the ability to find the right contract at the 2- or 3-level. Additionally, when opener passes 1NT with 12-14 (in my case 12-13) balanced, 1NT is often a good contract. However, sometimes it is not, and the main criticism of the semiforcing 1NT is that it harms the ability of responder to bid 1NT on a very wide range of shapely hands, assured of a rebid (which they would get in a F1NT style).
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#27 User is offline   mikeh 

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Posted Yesterday, 10:15

I think David and I were answering different questions. I may have misunderstood but I thought that jb wanted to know the likelihood of various club lengths in auctions that began 1S 1N 2C or 1H 1N 2C, when 1N was forcng.

Thus any calculation that caters to 0-1 club is irrelevant….opener won’t rebid 2C.

Moreover, it’s not as simple as calculating the relative frequencies of 2-6 clubs, since the 2C bid also denies various other holdings.

1S 1N 2C denies 6+ spades (technically not quite but very close), 4+ hearts and 4+ diamonds. Many hands with only 7 black cards will hold a 4+ red suit so we need to elmnate those…the only time 2C shows 2 is when opener is precisely 5=3=4=2.

And it’s a small point but David’s calculations slightly overstate the odds of having 4 clubs, since on a small number of hands opener will be 5404 or 5044, and will show the red suit.

Things are slightly trickier for 1H 1N since opener will rebid 2C with most 4=5=2=2 hands.
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#28 User is offline   DavidKok 

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Posted Yesterday, 10:19

The question at the start of the thread asked for the number of clubs held by responder, not opener.
I do not play most of opener's rebids the way you do, e.g. 1♠-1NT; 2♣ denying six spades.
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#29 User is offline   mikeh 

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Posted Yesterday, 12:39

View PostDavidKok, on 2026-May-24, 10:19, said:

The question at the start of the thread asked for the number of clubs held by responder, not opener.
I do not play most of opener's rebids the way you do, e.g. 1♠-1NT; 2♣ denying six spades.

I assumed JB was asking in the context of ‘standard’ 2/1, forcing 1N, in her area, which is (I think) western Canada at the moment. I have played that 2C doesn’t deny 6S, but that is very far from standard around these parts.
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#30 User is offline   thepossum 

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Posted Yesterday, 17:02

View PostDavidKok, on 2026-May-24, 10:19, said:

Said a lot, after I gave him the respect of mentioning him earlier
But sadly insulted me about my knowledge of sims and processing time




And his numbers are almost identical to mine - yet nobody had the decency to acknowledge them and the work and considerations I put into mine
I could post my basic script which took much longer than 8 seconds to think about and write and test - mine is just basic
When I say serious sim it would take a very long time to write all the bidding and systemic considerations

Please all of you move on from insults and disrespect - may acknowledge the effort of responding to the OP's question in detail too

My basic code is in the spoiler below to save space - some credit goes to chat GPT lol but mostly me
When I said a serious sim I was trying to be respectful to advanced players and professional sim writers :)
And there could easily be a logic error in seat configurations but I do not care - not sure there would be much difference in the stats - I did just run two separate runs to fix any alleged logic problem and the numbers are essentially identical in seat 1 or 2 :) My runs took 45 seconds - probably could be optimised :)
I am slightly embarassed at a logic error and biased stats but not really. And logic in two major hands and reverse considerations etc etc But I am sure the stats would not vary much. At least that was not a bias. It was opening one or the other
I imagine there is not much need for complex filters and sims to get a half decent estimate anyway but we need to please all the experts :)
Maybe people do not understand the anxiety associated with posting a sim on a forum like this

Spoiler

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