[rduran1216]

---

MPs

[Hanoi5]

16-18 is not a common range. If partner has the maximum we should be in game, especially if he shows up with 4 spades. If he shows 4 hearts I can invite (2NT), if he shows 4 spades I'd be tempted to drive to game right away and if he bids 2♦ I'd be tempted to pass. 2♣ for me.

[gwnn]

Oh sorry I didn't notice 16-18. Sure in that case I bid 2♣.

[mtvesuvius]

2♣ for me as well. It seems like all our normal response hands are shifted down a point. With a balanced 7, we could still choose to pass, similar to often passing balanced 8s facing a 15-17 NT.

[kenrexford]

This type of problem is why my wife and I play that...

1NT-2♣
2♥-2♠ and

1NT-2♣
2♦-2♠

...are sequences that show unbalanced hands with about this range and 4-5 spades. It seems to work well.

With the balanced hands with four spades, after the 2♥ rebid by Opener, bidding 2NT only costs when Opener has both majors and a minimum, and only if a spade contract is actually superior to the notrump contract, and only with those hands where partner with a minimum does not apply Crane's idea.

[pooltuna]

gwnn, on 2011-July-01, 07:25, said:

Oh sorry I didn't notice 16-18. Sure in that case I bid 2♣.

likewise it took me a while to find 16-18 and likewise I would try 2♣

[jillybean]

Playing 16-18nt 2♣ is obvious.

[ArtK78]

I don't think it is so obvious to bid over 1NT.

You have a maximum of 25 HCP (with your quota of 10s and a few extra 9s) and, if you do find a 4-4 fit, it might be a very weak 4-4 fit.

Maybe vul at IMPs it might make more sense to move over 1NT, but at matchpoints 1NT is probably as good a contract as any.

I would pass 1NT.

[semeai]

ArtK78, on 2011-July-01, 10:29, said:

You have a maximum of 25 HCP

They're even teaching beginners these days that game is good on 25 points: I watched a youtube clip of Andrew Robson's "Play Modern Bridge," a series introducing rank beginners to the game it seems, and he was teaching that 25 points meant game (in NT or a major). Link to his channel (see "Clip1").

[gordontd]

semeai, on 2011-July-01, 11:05, said:

They're even teaching beginners these days that game is good on 25 points: I watched a youtube clip of Andrew Robson's "Play Modern Bridge," a series introducing rank beginners to the game it seems, and he was teaching that 25 points meant game (in NT or a major). Link to his channel (see "Clip1").

Yes, but 12 opposite 13 is better than 7 opposite 18. And some of the time that you invite with 7, you'll be in 3NT with 7 opposite 17.

[daveharty]

I agree with ArtK78. Partner is far more likely to have 16 than 18. Even if partner does have the maximum to get us to the Magic 25 threshold, 3NT might not play so well with a likely natural heart lead from either side, so we might beat all the tables where the auction starts 1m-1S-2NT.

As an aside, I always thought the "25 for game" number was based on the likelihood that a combined 25 will provide enough tricks for game about half the time. Is it based on something less abstract than this? Or is it just the "Distilled Wisdom of the Ages", and the lowering of the number from 26 (a la Goren) to today's more common 25 simply represents increased aggression in modern bidding and an acceptance that bidding a few more bad games is worth it in the long run?

[Hanoi5]

daveharty, on 2011-July-01, 11:18, said:

Partner is far more likely to have 16 than 18.

Care to elaborate?

daveharty, on 2011-July-01, 11:18, said:

Or is it just the "Distilled Wisdom of the Ages", and the lowering of the number from 26 (a la Goren) to today's more common 25 simply represents increased aggression in modern bidding and an acceptance that bidding a few more bad games is worth it in the long run?

I don't remember the exact numbers but I think a vulnerable game should be bid at a 45% rate of success. A non-vulnerable game is closer to 50%. So yes, bidding is more aggressive than during Goren's days but they're not 'bad games', they're just more edgy to get closer to the success rate.

[gordontd]

Hanoi5, on 2011-July-01, 11:24, said:

I don't remember the exact numbers but I think a vulnerable game should be bid at a 45% rate of success.

At matchpoints?

[pooltuna]

gordontd, on 2011-July-01, 11:16, said:

Yes, but 12 opposite 13 is better than 7 opposite 18. And some of the time that you invite with 7, you'll be in 3NT with 7 opposite 17.

Nevertheless you probably have to try with this hand because with a ♠ fit the value of the ♥ singleton increases

[Phil]

Hanoi5, on 2011-July-01, 11:24, said:

Care to elaborate?

For the same reason that he would more likely hold 14 than 16 but less likely to hold 20 than 18.

[semeai]

gordontd, on 2011-July-01, 11:16, said:

Yes, but 12 opposite 13 is better than 7 opposite 18. And some of the time that you invite with 7, you'll be in 3NT with 7 opposite 17.

daveharty, on 2011-July-01, 11:18, said:

I agree with ArtK78. Partner is far more likely to have 16 than 18. Even if partner does have the maximum to get us to the Magic 25 threshold, 3NT might not play so well with a likely natural heart lead from either side, so we might beat all the tables where the auction starts 1m-1S-2NT.

As an aside, I always thought the "25 for game" number was based on the likelihood that a combined 25 will provide enough tricks for game about half the time. Is it based on something less abstract than this? Or is it just the "Distilled Wisdom of the Ages", and the lowering of the number from 26 (a la Goren) to today's more common 25 simply represents increased aggression in modern bidding and an acceptance that bidding a few more bad games is worth it in the long run?

I'm sure someone's done simulations, but I don't know the results. Certainly your last phrase is how I'd think about the declining number. Note that double-dummy results apparently favor the defense slightly (i.e. declarer typically does a bit better), if taken before the opening lead. See that thread by bluecalm that awm cited in the long bidding vs play thread.

In any case, this hand is worth more than 7 given that 10 and all those 9's in 4 card suits with other honors. In fact, K&R gives it 8.4.

[gwnn]

Hanoi5, on 2011-July-01, 11:24, said:

daveharty, on 2011-July-01, 11:18, said:

Partner is far more likely to have 16 than 18.

Care to elaborate?

[hrothgar]

gwnn, on 2011-July-01, 11:41, said:

Gaussians distributions ain't discrete
They also extended from -infinity to +infinity
And they're symmetric

Oh yeah, in this case the output is constrained...
However, your basic intutition is dead on

My hand generators are back at home.
However, I was bored enough to write one in MATLAB

Points = zeros(39,1);
Points(1:3) = 4; % 3 Aces
Points(4:7) = 3; % 4 Kings
Points(8:10) = 2; % 3 Queens
Points(11:12) = 1; % 3 Jacks

%% 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(17:19,:)


ans =

          16        4141
          17        2832
          18        2050

[gwnn]

There's also
http://www.bridgehan...ability_HCP.htm

Which gives the same ratio (~33:16) in favour of 16.

Anyway, a computational chemist will tell you that everything can be described by Gaussians, provided you take enough of them

[semeai]

Admittedly it's not gaussian, but gwnn's post gets the essential point across. Kudos for the quick code, though; I'm all for actual data over heuristics.

Alternatively, you can just go to wikipedia:

p(16 hcp) = .0331
p(17 hcp) = .0236
p(18 hcp) = .0161

So 16 hcp is more than twice as likely as 18.

Of course, these numbers will change a bit for balanced hands instead of all hands, but presumably not too much.

Added: Impressively, Pavlicek gets it without simulating.