[pescetom]

IMP pairs.

---

How does your partnership bid (assuming opponents stay silent) and to what contract?
Would anything change if the tournament was MPs instead?

[Tramticket]

We would likely play in 2H after a 1NT opening and a transfer.

[apollo1201]

We’d have some Drury sequence ending in 3S I guess.

P - 1S
2C! - 2D! (ambiguous, 2S promises 6 in our style)
2S - 2NT (not giving up yet cuz it’s IMP!)
3H (cuz it’s IMP) - 3S (definitely not), or 3S directly (I’ve done all I could, p), respected (me too, please pray that I can make it)

In MP, easy pass after 2S.

[mikeh]

where one ends up depends on methods.

Here, in all my partnerships, we play a strong 1N (14-16 in my regular, 15-17 otherwise) so it is trivial to open 1S.

Then South 'could' try a semi-forcing 1N, in my 14-16 partnership, or a non-forcing 1N in my others. However, even though 1N has a lot going for it, I think that the normal action is a drury call, that gets 2S by north who has a terrible hand. Yes, I see the controls, but I also see scattered values with hcp in short suits and a weak trump suit.

Now, 1N has upsides. We have enough values that we expect to make, especially as we rate to run spades. Our minor minor (sorry, I couldn't resist) honours are the sort of cards one wants in hand rather than in dummy, and rate to mesh well with partner should he pass 1N.

Of course the biggest upside is getting to hearts should partner have 4 of them. Now our hand grows up: not enough to force to game but definitely to invite.

The main downside is that if partner bids 2m, 3S by us is not only anti-systemic but is a huge overbid, but 2S may well miss a game. Meanwhile, if he rebids spades, do we raise? And if so, can he have much chance of getting it right?

At imps, I think drury is clear. At mps, one of these days I'd like to try 1N, but not today.

[nekthen]

1N 12-14
pass

simples

[pescetom]

Thanks to those who replied so far.
We stopped in 2♠, but many others were in 3♠ (which makes) or even 4♠, while nobody was in 1NT or 3NT (which makes).
I'd be comfortable with 2♠ at MPs, but wondered if it was an underbid at IMPs, even non-vulnerable.
I also wondered how many systems might lead to NT rather than spades (mikeh and nekthen outline two).

[mikeh]

pescetom, on 2019-March-07, 07:29, said:

Thanks to those who replied so far.
We stopped in 2♠, but many others were in 3♠ (which makes) or even 4♠, while nobody was in 1NT or 3NT (which makes).
I'd be comfortable with 2♠ at MPs, but wondered if it was an underbid at IMPs, even non-vulnerable.
I also wondered how many systems might lead to NT rather than spades (mikeh and nekthen outline two).

One should never analyze how to bid hands based on the result of any one hand or, indeed, any small sample of hands. Bridge is all about probabilities. Lest you have any doubt, run these two hands through a double-dummy analyzer and I am sure that you will find that game rarely makes, to the point that one would not want to be there even red at imps.

Note, by the way, what a difference it would make were North's middle club the 10. By itself that change, which to many people would not materially change the way they value the north hand, is worth nearly half trick.

[etha]

I can dbl dummy them back in a bit

[etha]

ok game in 3nt par 31/100 4♠ 30/100 rest part scores opps never had a successful sacrifice vs game. Hearts was better than spades twice.

once 4d dbled was par no idea if this beat 3nt or not though.

[mikeh]

etha, on 2019-March-07, 10:27, said:

I can dbl dummy them back in a bit

You're of course welcome to do so. However, one does not need double-dummy to know that this is a bad contract. Unless the opps are hopeless, one has to lose at least 1 diamond, 1 club and 1 heart. So one needs to be able to hold the club losers to 1. This can happen if the suit lies favourably for us, and can also happen if the defence breaks the suit and makes an error. We can also hope to jilt a club on a diamond if we can score 2 tricks. We do need them to break the suit or have a fortunate lie of the cards: we need KQ onside or a diamond lead.

We can also hope to establish hearts, but we need the suit to break and the hand to time out well. We have entry problems even with a 3-3 split.

And of course we are down on most 4-1 trump breaks.

BTW, double dummy analysis is particularly poor on these sorts of hands. For example, say opening leader against 4S has KQ9x in diamonds. In the real world many players would choose to lead that suit (although one needs to know the rest of the hand to be sure) but a double-dummy analysis will almost always assume a non-diamond lead, since the lead costs a trick immediately.

I don't use dd analysis in my system design or in valuation of bids for these reasons, but it can be useful if one has a large enough sample (I am no statistician but would want at least 1,000 hands) and is aware of the flaws.

[etha]

I can run another 900 hands if you want but i'm pretty sure the result won't change.


and you have to lead something.



I only did it dbl dummy because I was pretty sure your statement was wrong.

I can run them single dummy and I'm again pretty sure game is good. Admittedly the defense won't be as good as the declarer play.

[pescetom]

Here is the full deal as it turned out:

---

Spades and diamonds are benevolent.
Some even made 4♠ with a diamond lead, although I don't think it should be possible against competent defence, unlike 3NT.

[kuhchung]

come on guys you can't seriously be suggesting that we reach 3N on this type of deal, give me a break. double dummy simulations don't change that.

[pescetom]

mikeh, on 2019-March-07, 10:19, said:

One should never analyze how to bid hands based on the result of any one hand or, indeed, any small sample of hands. Bridge is all about probabilities. Lest you have any doubt, run these two hands through a double-dummy analyzer and I am sure that you will find that game rarely makes, to the point that one would not want to be there even red at imps.

Sure. I wasn't looking for a rule, just a sanity check having found that I was out of line with the field and that the hand played better than expected. I don't have the same assurance that I would have had it been MPs.

mikeh, on 2019-March-07, 10:19, said:

Note, by the way, what a difference it would make were North's middle club the 10.

I made exactly the same comment to partner, so that at least is reassuring

[mikeh]

etha, on 2019-March-07, 11:04, said:

I can run another 900 hands if you want but i'm pretty sure the result won't change.


and you have to lead something.



I only did it dbl dummy because I was pretty sure your statement was wrong.

I can run them single dummy and I'm again pretty sure game is good. Admittedly the defense won't be as good as the declarer play.

My statement was the effect that game was so unlikely to make that one would not want to be there even vulnerable at imps. Different people have slightly different numbers for that threshold, but I know of no competent player who thinks that one should bid 30% games.

The imp odds are that by staying low, one will usually win 6 imps when game fails, by being a net +240 (but this assumes no double and only 1 undertrick) while bidding and making game while the other table is +170 is 10 imps, so one needs 6/16 odds or 37.5%

However, often the reason the close game fails is bad breaks and on some of them they double. Moreover, on really bad days, 4S is down 2 while 3S is down 1, and one usually doesn't get doubled in 3S for a 1 trick set, so sometimes one goes for 500 against 100 or, in hands like these, against 110.

Against that is the reality that defence is usually harder than declarer play, which favours bidding game. My own rule of thumb is that I want to feel about a 40-45% chance to bid game, but (since one can rarely estimate this precisely) I tend to be aggressive on shapely hands and conservative on flat hands. North has a flat hand with poor spots.

[nullve]

mikeh, on 2019-March-07, 10:19, said:

run these two hands through a double-dummy analyzer and I am sure that you will find that game rarely makes, to the point that one would not want to be there even red at imps.

Ok, people can try

predeal south SAK2, HT9864, DJ5, CQ32
predeal north SQ9764, HA2, DAT2, CK96
action frequency (tricks(north,notrump),0,13)

here.

Here's one run:

Frequency :
    0	       0
    1	       0
    2	       0
    3	       0
    4	       0
    5	       0
    6	       0
    7	       3
    8	      16
    9	      21
   10	       0
   11	       0
   12	       0
   13	       0
Generated 40 hands
Produced 40 hands
Initial random seed 1552000326
Time needed    3.216 sec

[pescetom]

action frequency (tricks(south,notrump),0,13) is yet more prolific:


Frequency :
0 0
1 0
2 0
3 0
4 0
5 0
6 0
7 3
8 13
9 23
10 1
11 0
12 0
13 0
Generated 40 hands
Produced 40 hands
Initial random seed 1552053040
Time needed 2.654 sec

[TheoKole]

kuhchung, on 2019-March-07, 12:02, said:

come on guys you can't seriously be suggesting that we reach 3N on this type of deal, give me a break. double dummy simulations don't change that.

Reaching 3 NT is a stretch and a mistake whether it makes or not. Bidding systems are about reaching the best contracts most of the time. At the table, a very common auction would be
1 ♠ - 2 ♣ (Drury) - 2 ♦ (regular opener minimum) - 2 ♠ - P. Knowing whether partner has a particular 9 in order to fit with your 10's isn't part of any bidding system that I have read about.

[nige1]

Confirming the conclusions of Nullve and Pesceton

predeal south SAK2, HT9864, DJ5, CQ32
predeal north SQ9764, HA2, DAT2, CK96
produce 100
action frequency (tricks(south,notrump),7,10)

results

Frequency:
 7   		5
 8      	33    
 9      	62   
10   		0
Generated 100 hands
Produced 100 hands
Initial random seed 1552435945
Time needed    5.853 secs

[etha]

Just to point out mine are pretty similar too 30/100 plus 31/100 = 61/100.