Is this a psyche or cheating?

[pilowsky]

Pilowsky, on, I hope, a more constructive note, I thought I saw a remark of yours somewhere about developing a spreadsheet for the numbers of hands of certain shape(s), points, etc. If I'm not mistaken in this, I may well already have what you want and I'm happy to share it. If this of interest, please let me know.

 

Peter

 

Thank you - in fact, I had made this spreadsheet, but later discovered - that as with most of the great and useful things - it's available from multiple other sources. Playbridge, Wikipedia etc

Reconstructing it was helpful though and useful in embedding some of the probabilities.

[PeterAlan]

Thank you - in fact, I had made this spreadsheet, but later discovered - that as with most of the great and useful things - it's available from multiple other sources. Playbridge, Wikipedia etc

Reconstructing it was helpful though and useful in embedding some of the probabilities.

Beware: Wikipedia is not reliable. In particular, the statistics on the numbers of hands with X losers were hopelessly wrong when I last looked a while ago.

[pilowsky]

Beware: Wikipedia is not reliable. In particular, the statistics on the numbers of hands with X losers were hopelessly wrong when I last looked a while ago.

 

Thanks - The playbridge site also has the ACBL data. All the hands that I produce - apart from BBO and Step come from here http://www.playbridge.com/

[blackshoe]

<snip>

<snip>

 

I've always assumed that when I am explaining my own bid online, that I am explaining what the bid means, not what my partner thinks it means. Is that incorrect?

 

I've seen many players -- and I've done it myself -- explain their bid as a mis-click. In this situation (where I've mixed up two suits) I would explain the bid as a mis-click / mistake. Maybe I should just give an explanation based on our agreements, even if it's wrong.

Whoever is doing the explaining shouldn't be explaining what either player thinks the bid means or what the player who made the bid intended to convey by the bid. What should be explained is the partnership understanding as to the meaning of the bid (call, actually). Explaining that one has mis-clicked is extraneous and not required by the rules of the game or by its ethics.

 

Doing what one has seen many others do is quite common, and quite human. And quite often wrong.

[thepossum]

Defense is not my strong suit, however, on the actual auction I think that banging the spade Ace is really bad. On anything but a spade lead, the slam is going to make via the ruffing finesse. Note that even if you get a Spade lead, partner is going to signal for a club shift, and odds are that the slam will STILL make.

 

Let's assume a more normal auction (without the misbid). You'll probably see an auction like

 

1H - 2N

3C - 3D

3H - 4C

4H

 

Here, seeing the defense cash two Spades off the top is a lot more likely.

 

Thx Richard

 

It's just to me, with my fairly simple approach to things, and possibly not even noticing the implications of said alleged misleading bid I would have led my Ace anyway with that hand. But my play is certainly not up to the level of the protaganists at the table that day

 

Note, just ran a quick sim and that suggests the bid should not have changed the preferred lead (although obviously the superiority of the Ace lead is massively reduced). But my sims are not at that level either and am nervous even commenting in this company :)

[hrothgar]

 

It's just to me, with my fairly simple approach to things, and possibly not even noticing the implications of said alleged misleading bid I would have led my Ace anyway with that hand. But my play is certainly not up to the level of the protaganists at the table that day

 

 

In my experience, banging an Ace against a slam often works well. You may very well blow a temple (or worse yet lose the opportunity to cover a King), but balanced against this you get to see dummy and see whether partner is signally for an obvious shift.

 

However, banging an Ace in a suit where the opponents have shown shortness add an additional element of risk. If they have a void, you might very well see your Ace ruffed out. This happens way too often for my liking.

 

YMMV

[thepossum]

However, banging an Ace in a suit where the opponents have shown shortness add an additional element of risk. If they have a void, you might very well see your Ace ruffed out. This happens way too often for my liking.

 

 

 

Of course I appreciate that, and that risk is borne out by the Sim result. But even reducing your chance of making the Ace was not enough to totally wipe out the advantages of the Ace lead (in my veiw anyway), although depends on how you use means and confidence intervals. I should have mentioned the changes such that the CIs would now overlap with all other leads - but to me I'm still going with the estimated mean chance of defeating the contract - which is fairly slim :)

 

But as I said, my style of play is fairly basic and I was brought up with attacking rather than passive leads

 

Dislaimer - the above does not constitute professional opinion or advice in any discipline including statistics

[hrothgar]

Of course I appreciate that, and that risk is borne out by the Sim result. But even reducing your chance of making the Ace was not enough to totally wipe out the advantages of the Ace lead (in my veiw anyway), although depends on how you use means and confidence intervals. I should have mentioned the changes such that the CIs would now overlap with all other leads - but to me I'm still going with the estimated mean chance of defeating the contract - which is fairly slim :)

 

Dislaimer - the above does not constitute professional opinion or advice in any discipline including statistics

 

FWIW,in my experience if you are posting results based on simulations, it's often a good idea to post your code.

 

This gives folks a chance to understand what assumptions you are making and helps provide more confidence with respect to results.

[thepossum]

FWIW,in my experience if you are posting results based on simulations, it's often a good idea to post your code.

 

This gives folks a chance to understand what assumptions you are making and helps provide more confidence with respect to results.

 

OK will post my sim details. I need to regenerate them first. Or at least run another few thousand hands

 

Actually, as an interesting aside (maybe relating to another thread a few years back about Jacoby) I had to deal 2 million hands to get 1000 that fitted my constraints with the "misbid"

[thepossum]

On request for Richard. Note that this is still (and always will be) a draft. It is not a complete reviewed document, or anything and should never be used for any purpose other than Richard seeing my code etc

 

It was done purely as an interest exercise when I maybe should have been doing other things, with constant distractions, and also some anxiety about posting anything like this without it being properly checked and written up etc

 

Please bear with me - editing a few times to add results. It would take too long for me to format into friendly form so am just pasting Lua code (constraints) which I used with Bdeal (Beling) and the raw results with or without the 3S psych/misbid/mistake/whatever etc

 

Important note. It is a crude sim looking simply at defeating the contract or not and not making any assessment on number of tricks won/lost for matchpoint considerations etc I have a very simple approach to bridge, especially defence against a slam. I have in the past tried to work out a more sophisitcated distribution of the outcomes and how that distribution changes with different leads and the different bids. Its not much more code but could be provided if necessary. As I said it was a very simple sim :)

 

Results show mean number of tricks for declarer with each card led, with a 95% CI (I think it may be 1.96 SEs its not clear - I think the funny An symbol is +/-) but the Standard deviation and number of hands is also listed etc

 

As you can see without the 3S bid the 95% CIs do not overlap and the Ace (for me) is clearly the best lead in terms of average tricks and chance of defetaing the slam

 

With the 3S bid the difference in mean estimates is smaller and the 95% CIs do overlap. For me that doesn't affect thinking that the Ace is still a slightly superior lead etc

 

I'm not sure of the bdeal version but it was built on 27/11/18 (Australian date style)

 

Run on an HP Spectre 360X using Windows 10 etc on a sunny Friday morning somewhere in Australia

 

They are very basic scripts and assumptions. For example minium point ranges for E and W and assumption of 6+ hearts for W and 4+ hearts for E and (when used) the splinter being 0 or 1 tricks. I didn't put any other constraints on hand shapes - eg assumptions on Jacoby or number of losers in each hand etc

I didn't put any assumptions on controls etc. To make it more sophisticated I could have put in some loser and control assumptions that would lead to a 6H bid etc The configuration section has the North hand and requests bdeal to generate enough hands to get 1000 that fit the constraints.

The stats section calculates means and CIs for number of tricks and chance of declarer making slam for each possible card led

 

Note the funny copyright symbol is in the rendered HTML. It should be the letter c in parenthesies, ( c ) © "©"

 

--------------------------------------------------------------------------------------------------

--LUA Script for Bdeal v17.10.0 (Piotr Beling. http://bcalc.w8.pl/) without the 3S bid (my interpretation of point ranges etc)

--Written and run by the possum on 2nd Oct 2020

 

conf = {

N="at743.3.j962.j87",

num = 1000

}

 

function filter()

 

return W:hcp()>13 and W:hearts()>5 and E:hcp()>12 and E:hearts()>3

--and W:spades()<2

end

 

function stats()

for c in N:cards() do -- for each card c in the hand N:

local t = tricks(W, "H", c) -- tricks to take by E-W

count("E-W tricks after " .. tostring( c ), t)

count("chance to defeat after " .. tostring( c ), t < 12)

end

end

 

 

E-W tricks after C7: 12064 / 1000 = 12.064 Ań 0.0485418 (95% conf.) min: 10 max: 13 sdev: 0.782243

E-W tricks after C8: 12064 / 1000 = 12.064 Ań 0.0485418 (95% conf.) min: 10 max: 13 sdev: 0.782243

E-W tricks after CJ: 12070 / 1000 = 12.07 Ań 0.0486684 (95% conf.) min: 10 max: 13 sdev: 0.784283

E-W tricks after D2: 12066 / 1000 = 12.066 Ań 0.0479729 (95% conf.) min: 9 max: 13 sdev: 0.773074

E-W tricks after D6: 12067 / 1000 = 12.067 Ań 0.0479274 (95% conf.) min: 9 max: 13 sdev: 0.772341

E-W tricks after D9: 12073 / 1000 = 12.073 Ań 0.0480542 (95% conf.) min: 9 max: 13 sdev: 0.774384

E-W tricks after DJ: 12079 / 1000 = 12.079 Ań 0.0481777 (95% conf.) min: 9 max: 13 sdev: 0.776376

E-W tricks after H3: 12085 / 1000 = 12.085 Ań 0.0460116 (95% conf.) min: 10 max: 13 sdev: 0.741468

E-W tricks after S3: 12275 / 1000 = 12.275 Ań 0.0462453 (95% conf.) min: 10 max: 13 sdev: 0.745235

E-W tricks after S4: 12275 / 1000 = 12.275 Ań 0.0462453 (95% conf.) min: 10 max: 13 sdev: 0.745235

E-W tricks after S7: 12275 / 1000 = 12.275 Ań 0.0462453 (95% conf.) min: 10 max: 13 sdev: 0.745235

E-W tricks after SA: 11714 / 1000 = 11.714 Ań 0.0383639 (95% conf.) min: 10 max: 13 sdev: 0.618226

E-W tricks after ST: 12276 / 1000 = 12.276 Ań 0.0461807 (95% conf.) min: 10 max: 13 sdev: 0.744194

chance to defeat after C7: 232 / 1000 = 0.232 Ań 0.0261938 (95% conf.) min: 0 max: 1 sdev: 0.422109

chance to defeat after C8: 232 / 1000 = 0.232 Ań 0.0261938 (95% conf.) min: 0 max: 1 sdev: 0.422109

chance to defeat after CJ: 231 / 1000 = 0.231 Ań 0.0261543 (95% conf.) min: 0 max: 1 sdev: 0.421472

chance to defeat after D2: 229 / 1000 = 0.229 Ań 0.0260747 (95% conf.) min: 0 max: 1 sdev: 0.420189

chance to defeat after D6: 228 / 1000 = 0.228 Ań 0.0260346 (95% conf.) min: 0 max: 1 sdev: 0.419543

chance to defeat after D9: 225 / 1000 = 0.225 Ań 0.0259129 (95% conf.) min: 0 max: 1 sdev: 0.417582

chance to defeat after DJ: 224 / 1000 = 0.224 Ań 0.025872 (95% conf.) min: 0 max: 1 sdev: 0.416922

chance to defeat after H3: 214 / 1000 = 0.214 Ań 0.0254503 (95% conf.) min: 0 max: 1 sdev: 0.410127

chance to defeat after S3: 156 / 1000 = 0.156 Ań 0.0225169 (95% conf.) min: 0 max: 1 sdev: 0.362855

chance to defeat after S4: 156 / 1000 = 0.156 Ań 0.0225169 (95% conf.) min: 0 max: 1 sdev: 0.362855

chance to defeat after S7: 156 / 1000 = 0.156 Ań 0.0225169 (95% conf.) min: 0 max: 1 sdev: 0.362855

chance to defeat after SA: 319 / 1000 = 0.319 Ań 0.028923 (95% conf.) min: 0 max: 1 sdev: 0.466089

chance to defeat after ST: 155 / 1000 = 0.155 Ań 0.0224579 (95% conf.) min: 0 max: 1 sdev: 0.361905

Number of hands dealt: 696262. CPU time usage [sec]: 6.21 (x8 threads).

----------------------------------------------------------------------------------------------------

 

Notes

Without the 3S bid the Ace is the only lead with a mean number of tricks less than 12 (approx 11.75) 95% CI approx +/- 0.04-0.05 tricks

Chance of defeating the slam is approximately 32% with the Ace but only of the order of 22-23% with any other suit. CI +/- approx 2-3%

 

Clearly you would never lead a small spade - I could have excluded them from the sim :)

 

 

 

 

 

 

 

---------------------------------------------------------------------------------

 

--LUA Script for Bdeal 17.10.0 (Piotr Beling. http://bcalc.w8.pl/) with the 3S bid (my interpretation of point ranges etc)

--Written and run by the possum on 2nd Oct 2020

 

conf = {

N="at743.3.j962.j87",

num = 1000

}

 

function filter()

 

return W:hcp()>13 and W:hearts()>5 and E:hcp()>12 and E:hearts()>3

and W:spades()<2

end

 

function stats()

for c in N:cards() do -- for each card c in the hand N:

local t = tricks(W, "H", c) -- tricks to take by E-W

count("E-W tricks after " .. tostring( c ), t)

count("chance to defeat after " .. tostring( c ), t < 12)

end

end

 

 

 

 

E-W tricks after C7: 12265 / 1000 = 12.265 An 0.0499058 (95% conf.) min: 10 max: 13 sdev: 0.804223

E-W tricks after C8: 12265 / 1000 = 12.265 An 0.0499058 (95% conf.) min: 10 max: 13 sdev: 0.804223

E-W tricks after CJ: 12276 / 1000 = 12.276 An 0.0496369 (95% conf.) min: 10 max: 13 sdev: 0.79989

E-W tricks after D2: 12270 / 1000 = 12.27 An 0.0486684 (95% conf.) min: 10 max: 13 sdev: 0.784283

E-W tricks after D6: 12270 / 1000 = 12.27 An 0.0486684 (95% conf.) min: 10 max: 13 sdev: 0.784283

E-W tricks after D9: 12276 / 1000 = 12.276 An 0.0486179 (95% conf.) min: 9 max: 13 sdev: 0.783469

E-W tricks after DJ: 12282 / 1000 = 12.282 An 0.0485645 (95% conf.) min: 9 max: 13 sdev: 0.782608

E-W tricks after H3: 12289 / 1000 = 12.289 An 0.0466641 (95% conf.) min: 10 max: 13 sdev: 0.751983

E-W tricks after S3: 12494 / 1000 = 12.494 An 0.0385521 (95% conf.) min: 10 max: 13 sdev: 0.62126

E-W tricks after S4: 12494 / 1000 = 12.494 An 0.0385521 (95% conf.) min: 10 max: 13 sdev: 0.62126

E-W tricks after S7: 12494 / 1000 = 12.494 An 0.0385521 (95% conf.) min: 10 max: 13 sdev: 0.62126

E-W tricks after SA: 11951 / 1000 = 11.951 An 0.0407203 (95% conf.) min: 10 max: 13 sdev: 0.6562

E-W tricks after ST: 12495 / 1000 = 12.495 An 0.0384526 (95% conf.) min: 10 max: 13 sdev: 0.619657

chance to defeat after C7: 186 / 1000 = 0.186 An 0.0241459 (95% conf.) min: 0 max: 1 sdev: 0.389107

chance to defeat after C8: 186 / 1000 = 0.186 An 0.0241459 (95% conf.) min: 0 max: 1 sdev: 0.389107

chance to defeat after CJ: 182 / 1000 = 0.182 An 0.0239435 (95% conf.) min: 0 max: 1 sdev: 0.385845

chance to defeat after D2: 175 / 1000 = 0.175 An 0.0235787 (95% conf.) min: 0 max: 1 sdev: 0.379967

chance to defeat after D6: 175 / 1000 = 0.175 An 0.0235787 (95% conf.) min: 0 max: 1 sdev: 0.379967

chance to defeat after D9: 172 / 1000 = 0.172 An 0.0234182 (95% conf.) min: 0 max: 1 sdev: 0.37738

chance to defeat after DJ: 170 / 1000 = 0.17 An 0.0233098 (95% conf.) min: 0 max: 1 sdev: 0.375633

chance to defeat after H3: 156 / 1000 = 0.156 An 0.0225169 (95% conf.) min: 0 max: 1 sdev: 0.362855

chance to defeat after S3: 62 / 1000 = 0.062 An 0.0149648 (95% conf.) min: 0 max: 1 sdev: 0.241156

chance to defeat after S4: 62 / 1000 = 0.062 An 0.0149648 (95% conf.) min: 0 max: 1 sdev: 0.241156

chance to defeat after S7: 62 / 1000 = 0.062 An 0.0149648 (95% conf.) min: 0 max: 1 sdev: 0.241156

chance to defeat after SA: 213 / 1000 = 0.213 An 0.0254069 (95% conf.) min: 0 max: 1 sdev: 0.409428

chance to defeat after ST: 61 / 1000 = 0.061 An 0.0148516 (95% conf.) min: 0 max: 1 sdev: 0.23933

Number of hands dealt: 2044012. CPU time usage [sec]: 7.66 (x8 threads).

 

--------------------------------------------------------------------------------

 

Notes

With the 3S bid the Ace is the only lead with a mean number of tricks less than 12 (approx 11.95) but the 95% CIs overlap +/- approximately 0.05 tricks

Chance of defeating the slam is approximately 21% with the Ace but only of the order of 17-18% with any other suit. But the CIs overlap, they are +/- approx 2-3%

 

Note however the standard deviation for the Ace lead is now much larger etc. However the standard deviations for all other leads are very large too I could keep adding notes forever

 

Clearly you would never lead a small spade. I could have editted them out :)

[barmar]

I've always assumed that when I am explaining my own bid online, that I am explaining what the bid means, not what my partner thinks it means. Is that incorrect?

Ideally they should be the same thing. If you don't agree, then it's not really an "agreement", and you shouldn't explain it as such.

 

Of course, it's always possible to be mistaken about whether you actually have an agreement. But if you know that you don't have an agreement, you shouldn't explain it as if you do. Unfortunately, many players don't understand these subtleties, and will not believe a "no agreement" explanation.

 

Where things become tricky is when it comes to implicit agreements.

[mycroft]

Like "I've never played with BarMar before, but we're North American and play in Flight A, so I can bid 4H over 1NT and assume he knows it's spades?" How about "I don't know what variation of new minor we're playing, but he's not passing 1♦-1♥; 1NT-2♣? Or "we agreed basic 2/1. We have no agreement about 1NT-5NT, but that doesn't mean I can't bid it and expect him to not pass." Now, if our opponents are also North American and play in Flight A, then "no agreement, making flight A assumptions" would be full disclosure. If I was playing random Polish or Russian or Chinese pair, not so much.

 

As I have frequently said, I think "no agreement" is, pickups on BBO excepted, _prima facie_ incomplete information (and even with Pickups on BBO, I wouldn't use that, I'd say "you've seen our entire system discussion" or "we're playing his profile" or "he subbed in for my partner last round; no idea"). It's always "no agreement but". And I don't think it's fair that I say "no agreement" in the 2/1 auction I'm having with my friend and never partner L, knowing that we play Western (i.e. "shape rules, nothing shows extras") 2/1, and that we probably play most of what B taught T and I play with T, because he taught T and L at the same time.

 

Others may have a different opinion.

[barmar]

Bridge Winners had a poll last month about when "No agreement" can be considered adequate disclosure.

 

http://bridgewinners.com/article/view/how-often-is-no-agreement-a-sufficient-explanation/

 

There wasn't a concensus.

[glen]

There wasn't a concensus.

There was no agreement

[mycroft]

I think Frances, as forwarded by Bill, right up at the top of that discussion, expresses my opinions perfectly.

 

Except possibly the kind of snarky reaction I have (which Frances would never do, I'm sure!</innocent>) that the pro-"no agreement" brigade are the same as the ones that wish to push everything they can into "General Bridge Knowledge" and who use the phrase "It's Just Bridge" a lot. And they do all of those things because they truly believe that "knowing more about the game of bridge should be an advantage, one I see no reason to give up."

[Zelandakh]

I would hope there is agreement to the idea of making sure that the opponents have access to the same information as the pair doing the explaining.