Open BAM, opening lead

[sathyab]

[hv=d=s&v=e&s=saj54hj864d974c86]133|100|Scoring: BAM

1d-1h

2n-3n[/hv]

 

Opener does not deny four ♠s; responder could have checked back for 5-3 ♥ fit or 4-4 ♠ fit if he wanted to.

[xcurt]

I'll lead the spade. I really hate xx, there are just so many holdings it can pick up especially where RHO is likely to otherwise play me for any club honor. Of course the AJ-empty is unappealing too, but

 

* Even if partner has the Q I might get the trick back by cashing the 13th spade.

* If the opponents have the KQ but not the T, I could catch Hx on the left or HHx(x) on the right. Partner should have enough stuff to get in if we have deep spade tricks.

* Other things being close, the spade lead is easier for partner to read.

[lmilne]

I would lead a small spade without much thought.

[eyhung]

Taking it to the masses after you weren't satisfied with my spade answer, eh, Sathya?

 

I ran a sim of 1000 deals, with the following constraints:

 

RHO has 18-19 HCP semi-balanced with 2-4 spades, 2-3 hearts, and a 1D opener in shape (at least 4 diamonds, and diamonds are longest or tied for longest). No 4-4 minor-suit holdings are rejected.

 

LHO has 7-13 HCP with exactly 4 hearts, 0-3 spades, and 0-5 diamonds. He also would not have long clubs and game-forcing values.

 

Average # of tricks double-dummy on spade lead: 10.252

Average # of tricks double-dummy on club lead: 10.502

 

Make of that what you will.

[sathyab]

Taking it to the masses after you weren't satisfied with my spade answer, eh, Sathya?

 

I ran a sim of 1000 deals, with the following constraints:

 

RHO has 18-19 HCP semi-balanced with 2-4 spades, 2-3 hearts, and a 1D opener in shape (at least 4 diamonds, and diamonds are longest or tied for longest).  No 4-4 minor-suit holdings are rejected.

 

LHO has 7-13 HCP with exactly 4 hearts, 0-3 spades, and 0-5 diamonds.  He also would not have long clubs and game-forcing values. 

 

Average # of tricks double-dummy on spade lead: 10.252

Average # of tricks double-dummy on club lead: 10.502

 

Make of that what you will.

Actually I was thinking of posting this even earlier. In my private score sheet I had charged myself a half-board for this hand There appeared to be conflicting considerations here, so it seemed like a good candidate for a poll. It's just a coincidence that we exchanged notes about it earlier today.

 

I'll wait for a bit and post the full lay-out and also the results at other tables.

[gwnn]

spade lead.

 

Eugene, average # of tricks double dummy doesn't really help here does it? It would be better to know how many times they take less than 9 tricks. I think the two figures rate to be similar usually (lower # of average tricks means higher % of going down) but not always, especially with so low a difference (10.5 vs 10.2)

[eyhung]

The scoring is BAM, and the contract figures to be normal. I think avg # of tricks is much more relevant.

[gwnn]

right. next time I'll read the thread title :P

[gnasher]

I think that the most relevant figure is

 

sum(sign(tricks_on_spade_lead - tricks_on_club_lead))

[Jlall]

Taking it to the masses after you weren't satisfied with my spade answer, eh, Sathya?

 

I ran a sim of 1000 deals, with the following constraints:

 

RHO has 18-19 HCP semi-balanced with 2-4 spades, 2-3 hearts, and a 1D opener in shape (at least 4 diamonds, and diamonds are longest or tied for longest).  No 4-4 minor-suit holdings are rejected.

 

LHO has 7-13 HCP with exactly 4 hearts, 0-3 spades, and 0-5 diamonds.  He also would not have long clubs and game-forcing values. 

 

Average # of tricks double-dummy on spade lead: 10.252

Average # of tricks double-dummy on club lead: 10.502

 

Make of that what you will.

Did you simulate this with a diamond lead? I would lead a diamond over a club for sure, not sure about a spade vs a diamond. Wouldn't lead a heart.

[Fluffy]

its double dummy, some club leads latter require a spade back from partner, however when spade is right the defence is much easier.

[pooltuna]

Taking it to the masses after you weren't satisfied with my spade answer, eh, Sathya?

 

I ran a sim of 1000 deals, with the following constraints:

 

RHO has 18-19 HCP semi-balanced with 2-4 spades, 2-3 hearts, and a 1D opener in shape (at least 4 diamonds, and diamonds are longest or tied for longest).  No 4-4 minor-suit holdings are rejected.

 

LHO has 7-13 HCP with exactly 4 hearts, 0-3 spades, and 0-5 diamonds.  He also would not have long clubs and game-forcing values. 

 

Average # of tricks double-dummy on spade lead: 10.252

Average # of tricks double-dummy on club lead: 10.502

 

Make of that what you will.

see RGB

 

What is the MOE? Which could make the answer even fuzzier :)

[eyhung]

New 10000-hand sim to add in diamond analysis and 99% confidence MOE:

 

Spade lead = 10.1931

SD = 1.513

(t 99% for 10000 is 2.5763)

MOE = .0390

 

Diamond lead = 10.4881

SD = 1.312

MOE = .0338

 

Club lead = 10.4455

SD = 1.380

MOE = .0356

 

 

So with 99% confidence we can say that a spade is better than a club or a diamond double-dummy, but a club and diamond are close.

[eyhung]

Separate post for single-dummy analysis.

 

It would not surprise me if a diamond > club single-dummy. If declarer is going to pick up a suit without my help, he's more likely to correctly play partner for diamond honors because his diamonds rate to be longer than dummy's (such KTx opposite AJxxx). In contrast the opponent's club suit on this auction is biased towards length in dummy, something like AJ9x opposite KTx,and now your lead will fish out partner's queen when it was more likely to score. A positive for the club lead is that the lead may help set up partner's long suit, but as we can see from the DD analysis, it doesn't help as much as a spade.

 

I empathize with the people who do not like to lead spades because in a simulation Evan Bailey once ran, AJxx was the most dangerous holding to lead from vs. notrump from a top of suit perspective. KTxx (another 3 gap) was not far behind. In general I do not like to lead from such combinations, but sometimes you just gotta do it.

[gnasher]

One disadvantage of a diamond over a club is that a diamond may cost a trick by force, whereas a club can't. For example:

 

           108

  974               QJ43

            AK62

or

            K103

  974               AJ4

            Q862

[Jlall]

One disadvantage of a diamond over a club is that a diamond may cost a trick by force, whereas a club can't.  For example:

 

           108

  974               QJ43

            AK62

or

            K103

  974               AJ4

            Q862

I would guess that in practice a club blows a trick way way way more often which is not represented by double dummy, like when partner has Jxxx etc. Double dummy analysis does not account for a club lead picking off partner all the time because it plays...double dummy.

 

Also, if the entry position is tenuous in dummy, and you lead dummy's long suit, you may blow tricks by force in that layout, like dummy having QTxxx of clubs and one entry, and partner having KJx, or dummy having A9xxx of clubs and 1 entry, and declarer having Qx(x) etc.

 

The fact that double dummy likes a diamond better than a club shows in my mind that a diamond is going to be much better lead (which also backs my initial judgment that a diamond is much better than a club).

 

Then there is the fact that I think leading either minor will get your jacks picked off very often against a good opponent since a doubleton club and a diamond are so bizarre. Of course double dummy doesn't notice this :) This is a big mark for leading a spade.

 

edit: Somehow I didn't see Eugenes post above Gnasher, apologize for basically saying what he did.

[Jlall]

The sim constraints you are running are very biased towards a spade lead fwiw. They do not contain any hands where LHO is 4-4 majors. They also don't consider 5332 with 5 hearts. Of course this will vary widely based on who your opp is, but I often bid 3N with either 4-4 majors or 5332 majors (well, I have a bid that shows 5332 in my preferred methods without info leakage, but not playing that I often bid 3N). A spade is gonna cost a lot more when LHO has 4.

 

Still, looks like a spade is best.

[hanp]

I have often done double dummy simulations for opening lead problems. They tend to favor passive leads in a ridiculous way, I think they are completely useless.

[bluecalm]

I have often done double dummy simulations for opening lead problems. They tend to favor passive leads in a ridiculous way, I think they are completely useless.

 

This is opposite to what I noticed. Usually best double dummy lead = best lead in my opinion but I didn't run that many simuls (for sure less than a hundred).

[fred]

Spade lead has extra appeal at BAM because it looks so normal to lead a spade. At BAM you really don't want to put team in a position whereby the win or loss of a board could well be decided by how well a "weird" opening lead randomly happens to work out.

 

Fred Gitelman

Bridge Base Inc.

www.bridgebase.com

[TimG]

I have often done double dummy simulations for opening lead problems. They tend to favor passive leads in a ridiculous way, I think they are completely useless.

When comparing double dummy results to real world results, I found that the opening lead was all of declarer's advantage and in fact that the defense performed better vs double-dummy after the opening lead was made.

 

I was looking at average tricks taken (in various NT contracts played at IMPs), rather than frequency of one lead being better than another. So, it's quite possible that the passive lead produces:

 

9, 9, 9, 9, 9, 9, 9, 9, 9, 9 = average of 9 tricks

 

while the more aggressive lead produces

 

8, 8, 8, 8, 9, 9, 9, 10, 11, 11 = average of 9.1 tricks

 

but that you would want to pick the aggressive lead because it wins with higher frequency (at MP) or wins more IMPs.

 

It's quite possible that the real worlds results suffer from people sometimes choosing the passive lead, I made no attempt to classify any leads as passive or aggressive, standard or non-standard, etc.

[Mbodell]

When comparing double dummy results to real world results, I found that the opening lead was all of declarer's advantage and in fact that the defense performed better vs double-dummy after the opening lead was made.

That isn't that surprising when I think about it. In general, the declarer has more control and more decisions and hence more chances to vary from DD correct play. The defense have fewer opportunities (although they may be more important) after the opening lead which is their big advantage on most hands (if they get it right) and big disadvantage (if they get it wrong). Plus the opening leader is the only person who makes a play decision looking at only 13 cards instead of 27+ (hand+dummy+played cards).

[eyhung]

The fact that double dummy likes a diamond better than a club shows in my mind that a diamond is going to be much better lead (which also backs my initial judgment that a diamond is much better than a club).

Actually, the sim results say the opposite : a diamond (10.49) is slightly worse on average than a club (10.45) DD, but the margin of error is significant enough that it's possible a diamond is better. (Higher avg # of tricks is bad for the defense, not good.) I took the position, unsupported by the statistics, that a diamond is better than a club, single-dummy.

 

If you want to give me constraints where LHO holds 4 spades or 5332, I'd be happy to add that to the simulation. But I believe that most people will investigate for their 4-4 or 5-3 major suit fit unless they know the combined count is at least 28 HCP -- and some always investigate. Even in the Blue Ribbons, I was cussed out by an opponent sotto voce when I raised 2NT to 3NT with a 4-card major (and a combined count of 28) and she led my major, giving us an extra trick over the field in 4M.

 

I can also try to rerun the sim using gnasher and TimG's statistic -- frequency of win is important and can be lost in the averaging.

[Jlall]

The fact that double dummy likes a diamond better than a club shows in my mind that a diamond is going to be much better lead (which also backs my initial judgment that a diamond is much better than a club).

Actually, the sim results say the opposite : a diamond (10.49) is slightly worse on average than a club (10.45) DD, but the margin of error is significant enough that it's possible a diamond is better. (Higher avg # of tricks is bad for the defense, not good.)

Misread this, thanks, I was actually quite surprised that a diamond lead came up better double dummy, so this makes sense :)

[Phil]

I had two similar opening lead problems over the last week, except the suit was Axxx instead of AJxx.

 

I'd be curious to know how much the presence of the J makes (my guess is a LOT).