How would you invite to game?

[cherdano]

I would pass.

 

I expect partner to bid drury with a good 9-count and with all 10-counts. That doesn't mean game can't make but passing seems to be with the odds.

Just a question, not trying to start a fight. Does your partner place those same restrictions on your bidding, i.e., are you not allowed to exercise judgement about bad, fair, good, and excellent 10 counts and alter your bid based on your judgement?

Han would never dare to do that, as we recently agreed that good versus bad 9 counts is about the cutoff we use for drury versus 2S. (Of course, in case you are now going to post a 4333 hand with 3 queens and 4 jacks, including Jxx of trumps and Jxxx in a side suit, then we will just make fun of you as a point-counter.)

[han]

Of course we can't both have the king of spades....

 

♠QJ9xx

♥KQJx

♦Axx

♣x

 

You start drinking again? :(

Correction: we both can have the king of spades but we can't both have the king of hearts.

 

All of a sudden, Kxx, Kxxx, xx, xxxx looks to be a pretty good hand.

[han]

Some double dummy results with partner having 6-9 pts and 3-card support or 5-8 points with 4-card support, no shortness, out of 400 deals:

 

6 tricks: 9 times

7 tricks: 58 times

8 tricks: 123 times

9 tricks: 160 times

10 tricks: 43 times

11 tricks: 7 times

 

That should add up to about 400.

 

Game makes on 13% of those hands, 3S goes down on 47% of the hands.

 

If you play constructive raises then your expectations should be considerably better, if you play drury like we do then your expectations should be slightly worse. I expect double dummy results to favor the defense here by a small amount.

[H_KARLUK]

3H natural, We play 1M>2M "8-10 HCP" ; 1M>1N, 2x>back to 2 Opening Major "6-10 HCP" and does not guarantee 3 cards support

 

♠QJ9xx

♥KQJx

♦Axx

♣x

 

With his minimum best 8 HCP does not worth a try? At worst we have chance to run for 9 tricks. Easy to abort game. Isn't it?

[Winstonm]

I'm not sure what restrictions you are talking about.

 

I meant this:

 

I expect partner to bid drury with a good 9-count and with all 10-counts.

 

All 10 counts. That says to me he cannot make a judgement as to whether some 10-counts aren't good enough.

[han]

When I started posting on the forums I would often write things like "1NT = 15-17 HCP, or a decent 14-count with a nice 5-card suit or an bad 18-count with 4333-shape".

 

Once I passed 8000 posts I made two changes. I stopped downgrading 18-counts and I started writing "15-17 points" for the above, hoping that the rest was common sense.

[Winstonm]

Some double dummy results with partner having 6-9 pts and 3-card support or 5-8 points with 4-card support, no shortness, out of 400 deals:

 

6 tricks: 9 times

7 tricks: 58 times

8 tricks: 123 times

9 tricks: 160 times

10 tricks: 43 times

11 tricks: 7 times

 

That should add up to about 400.

 

Game makes on 13% of those hands, 3S goes down on 47% of the hands.

 

If you play constructive raises then your expectations should be considerably better, if you play drury like we do then your expectations should be slightly worse. I expect double dummy results to favor the defense here by a small amount.

Thanks. That's good. So under the parameters you set up, the hand makes 10 or 11 tricks 50 times and makes exactly 8 tricks 123 times. So the gain there would be 40.7% which should justify bidding game.

 

Now, I don't know if that is mathematically correct to compare only the times the hand makes exactly 8 tricks to the game hands - but if you are going down in 2 I don't think it will matter greatly if you go down in 3 - unless doubled.

[Winstonm]

When I started posting on the forums I would often write things like "1NT = 15-17 HCP, or a decent 14-count with a nice 5-card suit or an bad 18-count with 4333-shape".

 

Once I passed 8000 posts I made two changes. I stopped downgrading 18-counts and I started writing "15-17 points" for the above, hoping that the rest was common sense.

Han,

 

You should know by this time there is nothing common about common sense.

[han]

Some double dummy results with partner having 6-9 pts and 3-card support or 5-8 points with 4-card support, no shortness, out of 400 deals:

 

6 tricks: 9 times

7 tricks: 58 times

8 tricks: 123 times

9 tricks: 160 times

10 tricks: 43 times

11 tricks: 7 times

 

That should add up to about 400.

 

Game makes on 13% of those hands, 3S goes down on 47% of the hands.

 

If you play constructive raises then your expectations should be considerably better, if you play drury like we do then your expectations should be slightly worse. I expect double dummy results to favor the defense here by a small amount.

Thanks. That's good. So under the parameters you set up, the hand makes 10 or 11 tricks 50 times and makes exactly 8 tricks 123 times. So the gain there would be 40.7% which should justify bidding game.

 

Now, I don't know if that is mathematically correct to compare only the times the hand makes exactly 8 tricks to the game hands - but if you are going down in 2 I don't think it will matter greatly if you go down in 3 - unless doubled.

If you compare the numbers 100 and 200 then you could say that they differ by 50% or you could say that they differ by 100%, and both could be correct, depending on your viewpoint. But if you are talking about these things with someone else, it is a good idea to make sure that you have the same viewpoint otherwise it can lead to confusion.

 

If we ignore the hands where you have 6, 7 or 9 tricks then there are 173 hands left and 50 of those make game. My calculator says that is about 29% of those hands, not enough to make trying for game a good idea.

 

But you shouldn't ignore the hands with 6 or 7 tricks, because with those hands you score less well when you try for game. And you also shouldn't ignore the 9-trick hands, because no matter how accurate your invitations are, you will be in game on some of those hands and you will be in 3 when you actually should be in 4. Also, you will get to game on some hands where you only have 8 tricks, and then you will be down 2, and the usual odds needed to be in game don't apply.

 

If these numbers are close to accurate than it is really clear to pass. We can argue about whether the odds this simulation gives are accurate or not but we cannot argue about what they suggest if they are accurate.

[Winstonm]

Some double dummy results with partner having 6-9 pts and 3-card support or 5-8 points with 4-card support, no shortness, out of 400 deals:

 

6 tricks: 9 times

7 tricks: 58 times

8 tricks: 123 times

9 tricks: 160 times

10 tricks: 43 times

11 tricks: 7 times

 

That should add up to about 400.

 

Game makes on 13% of those hands, 3S goes down on 47% of the hands.

 

If you play constructive raises then your expectations should be considerably better, if you play drury like we do then your expectations should be slightly worse. I expect double dummy results to favor the defense here by a small amount.

Thanks. That's good. So under the parameters you set up, the hand makes 10 or 11 tricks 50 times and makes exactly 8 tricks 123 times. So the gain there would be 40.7% which should justify bidding game.

 

Now, I don't know if that is mathematically correct to compare only the times the hand makes exactly 8 tricks to the game hands - but if you are going down in 2 I don't think it will matter greatly if you go down in 3 - unless doubled.

If you compare the numbers 100 and 200 then you could say that they differ by 50% or you could say that they differ by 100%, and both could be correct, depending on your viewpoint. But if you are talking about these things with someone else, it is a good idea to make sure that you have the same viewpoint otherwise it can lead to confusion.

 

If we ignore the hands where you have 6, 7 or 9 tricks then there are 173 hands left and 50 of those make game. My calculator says that is about 29% of those hands, not enough to make trying for game a good idea.

 

But you shouldn't ignore the hands with 6 or 7 tricks, because with those hands you score less well when you try for game. And you also shouldn't ignore the 9-trick hands, because no matter how accurate your invitations are, you will be in game on some of those hands and you will be in 3 when you actually should be in 4. Also, you will get to game on some hands where you only have 8 tricks, and then you will be down 2, and the usual odds needed to be in game don't apply.

 

If these numbers are close to accurate than it is really clear to pass. We can argue about whether the odds this simulation gives are accurate or not but we cannot argue about what they suggest if they are accurate.

 

I certainly do not argue your mathematics skills. I am not mathematically inclined.

I am looking at this this way. The auction is 1S-2S. We are at 2 already so the only thing that matters is what happens if I make a game try - now a game try can get to 4 or stop in 3.

 

Of the times we bid on, only 50 times will we make game and 160 times we will be limited to 9 tricks - that is 31.2% - not enough reward.

 

Well done. Thanks for running the simulations.

[cherdano]

Lets say we are vulnerable at IMPs. The gains for a game try are easy to compute:

50 hands make game for a gain of 50*11 = 550 IMPs.

 

123 hands make 8 tricks for a loss of 123*5=615 IMPs.

67 hands make less than 8 tricks for a loss of 67*3 = 201 IMPs.

 

I hope this s clarifies how wrong it is to ignore the hands where 2S is down...

[maggieb]

That calculation assumes that you always get to game on the hands where you have 10+ tricks and always stop in 3 with the hands where you have at most 9 tricks. So the odds are actually larger than 816 vs 550. (adding... getting old! :) :))

 

Of course Arend's calculation is enough to see that inviting (at these odds) can't win.

 

I'm not sure I trust double dummy results in such a contract though.

[han]

Following rogerclee's suggestion I reran the simulation with a similar but better hand: KJ9xx KQJx Axx x. We both think that this is a clear invite so hopefully the simulation would support that. If not, perhaps the results shouldn't be taken seriously.

 

Out of 400 hands:

 

6 tricks: 3

7 tricks: 20

8 tricks: 100

9 tricks: 166

10 tricks: 99

11 tricks: 9

12 tricks: 3

 

So now if we assume that our inviting is perfect and we get to game on all hands with 10+ tricks and stop in 3S on all others then our results are:

 

111 times win 11: +1221 IMPs

100 times lose 5: -500 IMPs

23 times lose 3: -69 IMPs

 

This gives a total of +660 IMPs, overwhelming odds in favor of trying for game.

 

Of course the assumptions here are a little too rosy but these same assumptions said we should pass with the previous hand.

 

What a difference 1 HCP can make.. as expected?

[655321]

Thanks for these sims, Han, they are interesting.

 

BTW, it doesn't affect the results in any way but a vulnerable game is worth 10 IMPs not 11. :)

 

I have probably asked this question before, but what do people use to do the double dummy analysis of generated hands?

[Fluffy]

I had assumed 2♠ showed 8-10 (bad 10)

 

the hand Han posted (Kxx Axxx xx xxxx) althou I would also raise with it, is far from ideal then.

 

Trying for game when partner has shown a 6-9 raise is nuts.

[Fluffy]

What a difference 1 HCP can make.. as expected?

Double dummy analysys, so KJ9xx will play the trump suit so good catching the queen almost anywhere.

 

you also get perfect defence of course and opponents ruffing or removing dummy's trumps in time, but those are also present when you have QJ9xx.

[jdonn]

Fluffy has a very good point. Even though I agree with your point han, you have to admit a trump suit of KJ9xx will be overstated in the double dummy analysis, as its queen-catching abilities will be outstanding :)

[Winstonm]

Following rogerclee's suggestion I reran the simulation with a similar but better hand: KJ9xx KQJx Axx x. We both think that this is a clear invite so hopefully the simulation would support that. If not, perhaps the results shouldn't be taken seriously.

 

Out of 400 hands:

 

6 tricks: 3

7 tricks: 20

8 tricks: 100

9 tricks: 166

10 tricks: 99

11 tricks: 9

12 tricks: 3

 

So now if we assume that our inviting is perfect and we get to game on all hands with 10+ tricks and stop in 3S on all others then our results are:

 

111 times win 11: +1221 IMPs

100 times lose 5: -500 IMPs

23 times lose 3: -69 IMPs

 

This gives a total of +660 IMPs, overwhelming odds in favor of trying for game.

 

Of course the assumptions here are a little too rosy but these same assumptions said we should pass with the previous hand.

 

What a difference 1 HCP can make.. as expected?

That's pretty eye-opening. I would not have thought that there was that big of difference between QJ9xx and KJ9xx, all else being equal.

 

I suppose, those, it should, as those times that partner does have the Ace the chances of escaping for zero losers goes from virtually nil to decent.

 

I don't know if it can be done, but it would be interesting to see if it isn't this ability to capture the missing Queen that creates the disparity.

 

Thanks again, Han.

[Winstonm]

Fluffy has a very good point. Even though I agree with your point han, you have to admit a trump suit of KJ9xx will be overstated in the double dummy analysis, as its queen-catching abilities will be outstanding :P

It would be interesting (to me, anyway) to see how must change there would be with these 3 suits: QJ9xx, KJ9xx, and KJ109x.

[Cascade]

Lets say we are vulnerable at IMPs. The gains for a game try are easy to compute:

50 hands make game for a gain of 50*11 = 550 IMPs.

 

123 hands make 8 tricks for a loss of 123*5=615 IMPs.

67 hands make less than 8 tricks for a loss of 67*3 = 201 IMPs.

 

I hope this s clarifies how wrong it is to ignore the hands where 2S is down...

... and sometimes (especially when 2♠ was already down) we might get doubled at a higher level and lose a bunch more.

[han]

Fluffy has a very good point. Even though I agree with your point han, you have to admit a trump suit of KJ9xx will be overstated in the double dummy analysis, as its queen-catching abilities will be outstanding :)

I didn't make a point, nor did I try to make a point.

[jdonn]

Fluffy has a very good point. Even though I agree with your point han, you have to admit a trump suit of KJ9xx will be overstated in the double dummy analysis, as its queen-catching abilities will be outstanding :)

I didn't make a point, nor did I try to make a point.

What a difference 1 HCP can make

That's not a point? Sorry for the apparant mislabeling, next time I'll choose between phrase, clause, or parenthetical aside.

[han]

Whatever Josh, the simulation results were very different after changing a queen to a king. I pointed out that there was a big difference, this does not mean that I was making a point. I did not claim that the first simulation said we should pass nor did I claim that the second simulation says that we should invite with that hand.

 

In fact, I pointed out some factors why these simulations should be regarded somewhat skeptically. Fluffy pointed out one factor of why the results of the second simulation might be so different from the first simulation, I agree that that was a very good observation.

 

Also, I didn't run the second simulation to make a point, I ran it because (a) Roger asked me to run the same simulation for that exact hand, and (:) I thought that perhaps the first simulation results were more negative than they should be. Running the same search for a hand where my intuition says we should clearly invite can be a helpful: if the simulation results again suggested that one should pass then that would be reason to be even more skeptical about the first simulation. It turned out that this was not the case but that doesn't mean that either simulation should be accepted as enough evidence for the best call at the table, and I certainly didn't say they should.

 

It remains an interesting question how closely simulation results match real world results. I've read some work that was done in this direction but I never found what I was looking for. There is data suggesting that for large sets of hands (i.e. different hands dealt to us), the average number of tricks a double dummy simulation gives is quite close to the average number of tricks taken in real life, and that in real life, declarer tends to take more tricks in partscore contracts, fewer tricks in slams and about the same number of tricks in games, and for each of these situations the margin is not very large.

 

But that does not mean that for any specific hand the double dummy results will be close to the at-the-table results, it is easily possible that for some hands the real life results tend to be much more in favor of the defense while on others the results tend to be much more in favor of declarer. So I remain very skeptical about double dummy simulations.

 

I think perhaps the best use of simulations is as feedback for your intuition. I first try to guess how likely game or slam is and then I run a double dummy simulation to see if it agrees with my intuition. If not, I will look at few dozen hands manually to see if I can learn something. Sometimes the hands dealt to partner are very unrealistic and I will have to adjust the specifications. More often I notice some factors I didn't consider before, and hopefully I will have learned something.

[jdonn]

I think you are getting awfully nitpicky...

 

Of course no one believes double dummy will mirror real life, I was just agreeing with fluffy that a trump suit with a likely guess for a queen will in particular be very different between double dummy and real life. I think in fact it would be interesting to run it for trump suits of exactly Axxxx and Kxxxx and otherwise the same hand. I rather expect the difference between them to be smaller than the difference between KJ9xx and QJ9xx, but maybe I would become illuminated.

[Hanoi5]

This discussion went away from its original idea. If you invite with that hand or not wasn't exactly what I wanted to know (although I agree that it is a little too much). The is what try wouldyou use. My partner at the table used 2NT and I agree with whoever said that responder should/could bid the suit where he had 'help'. I failed to see this (I as responder would have bid 3♣ and my partner would have passed) but I think partner should have bid 3♦ (asking for help) or 3♥ (if it shows 4 cards, giving the choice between 4♥ and 4♠).