2NT or 3NT

[SimonFa]

I hate these decisions..

 

WvR, MPs

 

♠AQ532

♥K6

♦832

♣432

 

1NT (p) 2H (p)

2S (p) ?

 

Now what?

 

We play a style that never upgrades or downgrades into NT so 15-17 HCP is honest.

 

Normally on 9HCP and this vulnerability I would look to go to 3NT with 9HCP but all those little cards aren't very promising, even the 5 card spade suit doesn't fill me with enthusiasm.

 

In the end I took the 2NT route but in the knowledge that partner doesn't take much to accept an invite. With T98's I would have gone straight to 3NT

 

So a cowardly bid or pragmatic?

 

As a matter of interest, I've not seen anything on the distribution probability of HCP; what is the probability of partner having 15, 16 or17 HCP? Is it more likely that they will have 15 rather than 16 or 17? Or put another way, do the odds favour bidding 3NT with 9HCP?

 

 

 

Partner went to 3NT and made the contract - she had ♣AKQJT! - and made 10 tricks for 13/15

 

 

[Porreankel]

I think you did fine!

You have othing more than promised with a 2nt bid - and you rp can easily decide whats best from here.

Not even in IMP would I have bid different - so well done.

 

http://bridgetime.org/

[hrothgar]

 

As a matter of interest, I've not seen anything on the distribution probability of HCP; what is the probability of partner having 15, 16 or17 HCP? Is it more likely that they will have 15 rather than 16 or 17? Or put another way, do the odds favour bidding 3NT with 9HCP?

 

 

I consider bidding 3N clear cut.

 

With respect to the PDF of partner's HCPs. Here's what I came up with using a quick monte carlo sim

 

Partner is always much more likely to have 15 HCPs than 16; however, when you hold 9 HCPs the odds are even more skewed towards partner holding a 15 count.

 

 

    Points    Unconstrained    Constrained
    0        0.00359          0.00084    
    1        0.00759          0.00338    
    2        0.01363          0.00717    
    3        0.02414          0.01465    
    4        0.03905          0.02542    
    5        0.05187          0.03912    
    6        0.06586          0.05503    
    7        0.08084          0.07007    
    8        0.08861           0.0849    
    9        0.09319           0.0959    
   10         0.0954          0.10055    
   11        0.09017          0.09698    
   12        0.08004          0.09214    
   13        0.06724          0.08049    
   14        0.05687          0.06816    
   15        0.04461           0.0548    
   16        0.03307          0.03928    
   17        0.02367           0.0281    
   18          0.016          0.01847    
   19        0.01026          0.01148    
   20        0.00628          0.00655    
   21        0.00403          0.00363    
   22        0.00217           0.0017    
   23        0.00085          0.00066    
   24        0.00055          0.00037    
   25        0.00029          0.00011    
   26         7e-005           3e-005    
   27         2e-005           1e-005    
   28         1e-005           1e-005    
   29         3e-005                0    
   30              0                0    
   31              0                0    
   32              0                0    
   33              0                0    
   34              0                0    
   35              0                0    
   36              0                0    
   37              0                0    
   38              0                0    
   39              0                0    
   40              0                0    


Points = zeros(39,1);
Points(1:3) = 4;
Points(4:6) = 3;
Points(7:9) = 2;
Points(10:14) = 1;

%% shuffle

simlength = 100000

MC_Result = zeros(simlength, 1);

for i = 1:simlength
   
   index = randperm(39);
   Points = Points(index);
   MC_Result(i) = sum(Points(1:13));
   
end
   
mean(MC_Result)   

Output = 0:40;
Output = Output';

for i = 1:41

   Output(i,2) = length(MC_Result(MC_Result == i-1));
   
end

Output

[aguahombre]

Forum posters who have opened 1NT (15-17) have pretty much agreed in the past that they (we) accept invites on the vast majority of 16's and even some 15's. If playing with a forum poster, the invite was fine.

 

The important thing about charting the probabilities on whether partner has a good 1NT opener or a bad one is this: she gets to look at her hand when invited, so we don't have to guess whether to bid game all by ourselves.

[mgoetze]

WvR, MPs

 

[...]

 

Normally on 9HCP and this vulnerability I would look to go to 3NT with 9HCP

 

I don't quite understand... white at Matchpoints is not the situation where you need to look for games very aggressively! I think 2NT is perfectly normal.

 

As a matter of interest, I've not seen anything on the distribution probability of HCP; what is the probability of partner having 15, 16 or17 HCP? Is it more likely that they will have 15 rather than 16 or 17?

 

15 HCP 44%

16 HCP 33%

17 HCP 23%

 

(100,000 simulations, no 5-card majors in 1NT)

[mgoetze]

In case anyone cares, I suppose I'll show my work too

 

source /usr/share/deal/format/none

south is "AQ532 K6 832 432"

set fifteen 0
set sixteen 0
set seventeen 0

main {
if {![balanced north]} {reject}
if {[hcp north] == 15} {
	set fifteen [expr $fifteen + 1]
	accept
}
if {[hcp north] == 16} {
	set sixteen [expr $sixteen + 1]
	accept
}
if {[hcp north] == 17} {
	set seventeen [expr $seventeen + 1]
	accept
}
reject
}

deal_finished {
puts "15 HCP: $fifteen"
puts "16 HCP: $sixteen"
puts "17 HCP: $seventeen"
}

 

% deal -i hcp.tcl 100000
15 HCP: 44138
16 HCP: 32855
17 HCP: 23007

[pooltuna]

invite at MP go to game if V at IMPS

[hrothgar]

In case anyone cares, I suppose I'll show my work too

 

I, for one, think its useful to show the scripts that people use to generate sims.

 

Its the easiest way to check assumptions and for correctness.

And who knows, it might help inspire folks to learn a new skill.

 

FWIW, I reran my sim (generating a million hands)

 

My estimates for the relative frequency of 15:17 was essentially identical to Michael's

 

15 HCP = .4426

16 HCP = .3282

17 HCP = .2292

 

Going back to the real question:

 

I still think that bidding 3N is pretty clear.

I'll be interested to see whether the consensus changes once Justin gets dragged in.

[gwnn]

Looks like a clear 3N. Prime 9 count. Yes, there's not so many intermediates, but what can you do..

[Free]

but what can you do..

Invite :P

 

Personally I don't have strong feelings about this decision. If you know your partner will accept light, then 2NT seems fine to me.

[billw55]

Interesting. To my eye this is an open and shut invite, I did not expect anyone to advocate a direct 3NT. And yet there they are.

 

The biggest consideration to me:

 

The important thing about charting the probabilities on whether partner has a good 1NT opener or a bad one is this: she gets to look at her hand when invited, so we don't have to guess whether to bid game all by ourselves.

Right. Why on earth would I care what the probabilities are of 15 v. 16 v. 17? My partner already knows what he holds. I expect him to accept with any 17; or with 16 and any bonus feature (such as a five card suit, working ten, Hx of spades, high honor quality); or even with an exceptional 15.

 

Bidding 3NT myself is just anti partnership.

[SimonFa]

I don't quite understand... white at Matchpoints is not the situation where you need to look for games very aggressively!

 

That's where I'm going wrong.

[ggwhiz]

A lot depends on the rest of your methods.

 

We super accept the transfer aggressively with either 2nt or 3♠ so bidding 2nt here is plenty for us.

 

That invitation is also accepted aggresively by opener so 3nt would be a hang job.

 

Note: Just looked at the spoiler and at these colours and with those clubs we might open 1nt with some real cheese in the other suits.

[aguahombre]

Note: Just looked at the spoiler and at these colours and with those clubs we might open 1nt with some real cheese in the other suits.

But, I bet you would accept an invite with that; I would, and it would just make partner's blast to 3NT on his hand irrelevant and also annoying whether it makes or not.

[gwnn]

Anti partnership and annoying? I invite when I think I have an invite and I force to game when I think I have a game force. I don't see where the problem is. I admit I am somewhat biased against inviting, I tend to try to either stop low or force to game, but I am not doing this because I disrespect my partner or I try to annoy him. I just don't like declaring/being dummy in 2NT, the odds are against us.

 

This is not to say I never invite. I do invite when I think invitation is the best course of action. I don't think 3NT is clear here at all, it's just that I would bid 3NT.

[gwnn]

To the OP:

I hate these decisions..

you shouldn't hate these decisions. They don't matter in the long run. You can bid 2 or 3 NT and if you think it's very close, you can bid whichever you feel like. It really isn't a big deal.

[VM1973]

In my opinion this is a clear invite. In a plurality of cases your partner will have 15 HCPs. If he has more, he'll go.

[MrAce]

Imo you should ignore any reply that makes a long analysis and ends up saying this hand is CLEAR 2 NT or clear 3 NT. You know, i know and everyone else here knows the outcome of your decision in the long run will have very less to do with mastermind analysis of a 9 count 5332 hand vs a NT opener at mp. At imps you should bid game if you are not sure whether to bid game or invite by default.

[MickyB]

There is one non-obvious factor to take into consideration - for most, bidding 3NT will end the auction opposite a 3(433), but bidding 2NT will lead to 3S or 4S.

[Phil]

I'd invite.

 

The spotless spades are of questionable value if partner does not fit them. Do you really want to be in game with 15 (or even the upgraded 14) opposite a hand with a doubleton?

 

However if pard does take preference back to 3♠ then I will try 3N which I expect pard will sit for unless he has a ruffing value or maybe an open suit.

 

If I were to blast game I would have just bid 3N the 1st time which I expect to make a lot. I also think a spade lead is quite possible on this auction. Its great when this rides over to pard's Jx.

 

As an aside I play 1N - 2♣ - 2x - 2♠ as a weak invite so 2N shows a good invite which is exactly what this hand is.

[aguahombre]

There is one non-obvious factor to take into consideration - for most, bidding 3NT will end the auction opposite a 3(433), but bidding 2NT will lead to 3S or 4S.

That is an interesting point. What it does mean on this hand (to me) is that, while opener might well be 4x3, responder has asked opener whether he is min/max and whether the partner does or does not have a spade fit. If opener decides to accept the invite and bid 3NT with a flat hand including spade support, I would think he is playing Bridge from one side of the table just as much as responder would have been doing if he blasted to 3NT. Responder showed five spades as something more than a knee-jerk drill; if opener isn't going to agree spades with a flat hand, responder was wasting his effort and might as well have kept the opponents in the dark. (Those who disagree with this will hopefully do so in reasoned debate.)

 

Would he also pass 2NT with a minimum and 3-card support? Maybe responder has one of those hands where he will decide to continue to game because of the spade fit. Maybe this is one of those hands.

[Porreankel]

MP is NOT about gambling on game!

Let the poor people bid 3Nt here - and bid 2NT if you want to play healthy - telling your partner exactly what you have, and let him decide. It is called bridge :-)

 

Yes sometimes you will stand in 2NT winning 9 tricks - so be it....

Decisions, not results!!

 

Read this post if you want more info:

 

http://bridgetime.org/decisions-not-results/

[jjbrr]

With 9 points and a 5-card suit I always force to game opposite a 1NT opener

[Porreankel]

With 9 points and a 5-card suit I always force to game opposite a 1NT opener

 

Why ???

 

After having made the Jacoby 2h bid, and then the 2NT bid, your partner already know you have 5 spades and 9~ish points.

Let him be the captain now.

[jjbrr]

Because I make game often enough that I think it's +EV

 

9HCP with a 5-card suit is kind of like 10HCP anyway