How likely is likely?

[dburn]

Research indicates that the claimer was one of the team that won last year's Gold Cup - except that it wasn't me, so may have been my replacement. Further details will be added as they become available.

[lamford]

According to the opening post, West claimed after South had led a 4th heart. One possible explanation of the claim was that West had not appreciated that dummy would have to follow to the 4th heart; If dummy had been now void of hearts, then ruffing with the 10 or 8 would have been a 100% line.

I expect he would then have stated "cashing the king or queen first, so that I can pick up Jxxx in either hand", as I think that he could be ruled against if he did not.

 

Gordontd seems to think South is more likely to have a singleton spade for the 1H overcall, but I am unconvinced. Applying restricted choice to a situation where an opponent overcalls is fraught, as he looks at his cards before bidding (at least adherents to 7B2 do). In fact it is quite surprising when someone overcalls with a four-card suit, and especially so given the defenders have eleven clubs between them. If West's longest suit is hearts, then he is very likely to have a doubleton spade, as the four-two heart break will be more than compensated by a putative four-seven club break. I disagree with dburn's assertion that it is slightly better to ruff high and finesse - it is too close to call.

 

I would rule one off - up to the end of the correction period - wherever the jack of spades is. But in response to the opening post, is it not for the WBFLC to pronounce on how likely they intend likely to be? Dictionary meanings vary from plausible to probable, so we rule in favour of the non-offenders if it is plausible that the declarer would have lost a trick. We know likely cannot mean >50% from a sentence such as "there were several likely candidates".

[gordontd]

We know likely cannot mean >50% from a sentence such as "there were several likely candidates".

This seems to me to just be nonsense, since all we are determining is whether something is likely or not. In that context likely as >50% seems eminently reasonable.

 

I can make up a sentence like "There is only one likely outcome". Does this mean that likely = 100%? Of course not.

[gordontd]

Research indicates that the claimer was one of the team that won last year's Gold Cup - except that it wasn't me, so may have been my replacement. Further details will be added as they become available.

The further detail that has come to me (by way of a phone conversation with one of the players at the table) is that they were in 5♠, not 4♠, so they had already gone off at the moment of the claim and no-one realised that there was more to the hand. The match was close enough until the final two boards that an extra undertrick could have been significant.

[Trinidad]

We know likely cannot mean >50% from a sentence such as "there were several likely candidates".

This seems to me to just be nonsense, since all we are determining is whether something is likely or not. In that context likely as >50% seems eminently reasonable.

 

I can make up a sentence like "There is only one likely outcome". Does this mean that likely = 100%? Of course not.

While I am not necessarily agreeing with lamford, your reasoning is not 100% correct. If one states that there is one likely outcome than that implicitly means that there are 1 or more unlikely outcomes. Now, if there is 1 other outcome with a probability of 1 %, the likely outcome has a probability of 99%. But it may well be that there are 900 unlikely other outcomes, each with a probability of 0.1 %. That leaves 10% for the "likely outcome".

 

In short, the boundary for what is "likely" could, in principle, be anywhere.

 

Now, we happen to be very fortunate here. There are only two possible outcomes:

A: Declarer chooses a winning line with the outcome that he makes his contract.

B: Declarer chooses a losing line with the outcome that he goes one down.

 

So, in this particular case, I think "likely" is defined as "more likely than the other possible outcome", which is than equivalent to >50%.

 

Rik

[aguahombre]

Depends on the player. I would give the claim to Hamman. Watching VuGraph I have seen him in instances similar to this, where each time he just played the interior trump, rather than roughing up and hooking. I believe he was right once and wrong twice, so this would get him to even.

[lamford]

This seems to me to just be nonsense, since all we are determining is whether something is likely or not. In that context likely as >50% seems eminently reasonable.

 

I can make up a sentence like "There is only one likely outcome". Does this mean that likely = 100%? Of course not.

You would be right if there were a single trick remaining, but I think that most TDs can establish whether it is likely that someone would win trick 13 or not. Most of the time, however, there will be several tricks remaining, with a different probability of each being won by either side. In this example, there is a probability that North will win this trick with the five of spades - let us say that it is 5%. There is a probability that South will win a later trick with the jack of spades - let us say that this is 49%. You would argue that there is no trick that it is likely that the defence would have won, as none of them is individually greater than 50%. Perhaps the criterion should be that the sum of the probabilities of all the likely tricks the defence might have won should be greater than 50%. But it is clearly not required that likely means >50% in that context.

[lamford]

So, in this particular case, I think "likely" is defined as "more likely than the other possible outcome", which is than equivalent to >50%.

 

Rik

The Law does not say "likely to make his contract". It refers to any trick that was likely to have been won.

[Finch]

Depends on the player. I would give the claim to Hamman. Watching VuGraph I have seen him in instances similar to this, where each time he just played the interior trump, rather than roughing up and hooking. I believe he was right once and wrong twice, so this would get him to even.

 

I doubt Hamman does it without thinking about each hand individually

[aguahombre]

Was feeble attempt at humor

[bluejak]

"would likely have won ..."

 

Declarer might have ruffed with the 8 or 10, but that seems pretty unlikely. So let us eliminate that.

 

No doubt declarer would have ruffed high, then considered which high trump to cash next. Heart 4-2, clubs unmentioned, how many would South have? I don't think this tells him much, though you might infer that South is unlikely to have six or seven clubs. But you have no idea of the diamond distribution. Eventually, declarer will cash a high trump, let's say either one equally, then lead another, ponder [if the jack has not appeared], and finesse 50% of the time [or less: personal view: even top players do not like finessing against jacks]. So the defence will make a trick one time in four at most.

 

In my understanding of the English language, that might be considered "might have won" but certainly not "would likely have won ...".

[gordontd]

Eventually, declarer will cash a high trump, let's say either one equally, then lead another, ponder [if the jack has not appeared], and finesse 50% of the time [or less: personal view: even top players do not like finessing against jacks]. So the defence will make a trick one time in four at most.

I've asked various players about this hand this week. They all thought it was close, but all but one of them finessed. The other one finessed the other way, but admitted he had no reason for playing that way. So, you think it's about 25% while I would think it's well over 50%.

[phil_20686]

Everyone seems to think that finesse is %, but I dont. I think playing for 2-2 spades is % by a reasonable margin:

 

(1) People generally only make 4 card over calls when they have a decent hand, so it seems right to put south with both the club honours. Certainly he must have one.

(2) Few people would choose the 4 card heart suit if they had a 6 card club suit. Its too big a distortion, so it seems likely that south is 2-4-2-5 or 2-4-3-4.

(3) If south has 3 spades to the J he would have made a take out double. - it is inconceivable that he has too few clubs.

 

Given this, I think it is a prior 5/9 that north holds the spade J. However, if you have excluded from the south hands hands with 3, 4 or 0 spades, then 2-2 is a prior more likely than a given 3-1 break by nearly 15%. In fact, if we simply removed the excluded shapes the spades are roughly 40/(40+0.5*50) = 8/13 to be 2-2. Considerably better odds.

 

I'm pretty tired right now so might have overlooked this. Maybe one of the better players can confirm, but it seems like 2-2 spades are favoured.

[phil_20686]

because I was too lazy to think any more, I demanded that south have 5 or fewer clubs, fewer than 3 spades (else t/o double), and at least two diamonds (again not a t/o double) with both the kq of clubs, and on those conditions my sim of 25 hands found 5 boards where the finesse wins, and 9 where the drop wins and 11 where either win. This seems roughly in line: with what I guesstimated above.

 

So I would ruff this high and play a second top trump from my hand. assuming no J of spades it is now right to cash the second top spade.

[gordontd]

Few people would choose the 4 card heart suit if they had a 6 card club suit. Its too big a distortion, so it seems likely that south is 2-4-2-5 or 2-4-3-4.

Your conclusion doesn't follow from your premise (not that I accept your premise - who was that author whose players at Ann Arbor bridge club seemed to endlessly bid four-card majors with a six-card minor on the side?)

 

What about 1-4-4-4, 1-4-3-5?

[phil_20686]

Your conclusion doesn't follow from your premise (not that I accept your premise - who was that author whose players at Ann Arbor bridge club seemed to endlessly bid four-card majors with a six-card minor on the side?)

 

What about 1-4-4-4, 1-4-3-5?

 

Sure, he can have those hands. Was pretty tired last night, but the point is its essentially impossible for him to have 3 spades. If you want to compare the odds you should be including only 3/8 of all 3-1 distributions (barring singleton J) where the finesse is right, compared with all 2-2. Since originally each 3-1 break was 50%/8=12.5, and we are left with 3. Whereas we still can pick up all 2-2 breaks. Moreover, if you give lho 6 clubs to go with his two hearts, then both hands have the same number of spaces, so there is no reason to prefer the spade finesse to the drop. I think most people were being lazy and only considering the heart layout as "known" and not the bidding inferences. 4 card overcalls tend to imply a good hand, which means south would (barring an 8-2 club break) always have a t/o double if he has 3 spades.

 

I mean, its obviously somewhat close, but I would expect the drop to be "significantly" better, probably 8-10% or so. That is my intuition anyway.

[gordontd]

Sure, he can have those hands. Was pretty tired last night, but the point is its essentially impossible for him to have 3 spades.

That's why we're not considering taking the finesse the other way

 

If you want to compare the odds you should be including only 3/8 of all 3-1 distributions (barring singleton J) where the finesse is right, compared with all 2-2. Since originally each 3-1 break was 50%/8=12.5, and we are left with 3. Whereas we still can pick up all 2-2 breaks.

Shouldn't you only be considering half of 2-2 breaks, since those with Jx in North will have been revealed at the moment of decision? You can pick up all 2-2 breaks, but only if you know they're breaking 2-2. You can also pick up all 3-1 breaks with a singleton in South, but you still need to make a decision.

 

Moreover, if you give lho 6 clubs to go with his two hearts, then both hands have the same number of spaces, so there is no reason to prefer the spade finesse to the drop. I think most people were being lazy and only considering the heart layout as "known" and not the bidding inferences.

I thought you shouldn't take unknown suits into account to calculate vacant spaces. Whether I'm write or wrong about that, it was clearly the view shared by nearly all those I asked how they would play it, which is why I concluded that it was "likely" (ie above 50%) that the finesse would be taken.

 

4 card overcalls tend to imply a good hand, which means south would (barring an 8-2 club break) always have a t/o double if he has 3 spades.

I don't think anyone has posted anything in contradiction of that.

 

I mean, its obviously somewhat close, but I would expect the drop to be "significantly" better, probably 8-10% or so. That is my intuition anyway.

I'd have expected more than intuition for a claim of that magnitude.

[bluejak]

People generally only make 4 card over calls when they have a decent hand, so it seems right to put south with both the club honours. Certainly he must have one.

 

I don't think anyone has posted anything in contradiction of that.

Well, I haven't because I thought the whole analysis was irrelevant, not because I agreed with it.

 

I make four-card overcalls when I have a good suit that I want led, and am especially likely to make them when I have nothing else I want led. So in my case I would be unlikely to have either club honour.

 

But I do not see its relevance to the thread.

[gordontd]

I carefully split up Phil's post and responded to each bit separately. You've taken one of my responses and put it beneath something from an entirely different post, as though I had been responding to that.

[phil_20686]

The claim for the adjustment was based on the fact that the "normal" line would lead to two off. I was merely pointing out that the analysis of the "normal" line was clearly flawed. It seems relevant if the "normal" line actually does lead to one off.

 

Besides that, its interesting in its own right.

 

@Gordon

 

Whether you should use "unknown suits" in vacant spaces is often somewhat grey area. The point is that from the bidding you have inferences that assign greater likely hood to some distributions more than others. An obvious example. Suppose the opposition opened 4H and you bid to 6S, and need to find a Q in a two way finesse. The preemptor turns out to be void in spades. Technically that is your only "known" suit, but it would be facile not to conjecture that he will have at least 7 hearts, so one should count that as "known". The point about unknown spaces is mostly that you should not bother conjecturing too deeply about the positions of other suits, as it automatically takes into account the a priori distribution of suits. Perhaps you are confusing it with the the fact that you should not consider discards of a suit as "known" cards.

 

As to what you should consider, well its a bit deep. If you agree that south should have a good hand, and with the hands I excluded, then the Sim suggested that both work roughly half the time, of the remaining cases the drop works nearly twice as often as the finesse. Of course, if you disagree about what hands to exclude (and its not completely clear cut) then the sim will start to reflect the vacant spaces argument more and more. The key point is that for a 4 card overcall south should always have enough for a t/o double if he has 3 spades, and also that with 6 clubs he will normally have enough extra shape to bid 2C if he had enough HCP for a t/o double in a balanced hand.

 

Another way to look at it is just to note that the vacant spaces argument predicts 11/20=55% for the finesse, but if you exclude rho from having 3 or 4 spades, then 2-2 distributions make up 40/(40+18+5)= 8/13= 62%. (in my head so approximate). Of course, the finesse also picks up Jx onside, which but the drop also picks up stiff J.

 

More accurate calculation, excluding RHO having 3 or 4 spades, but using the a priori otherwise:

Assume that you start with a top one and a spade up, then at the decision time:

Finesse: Jxx/Jxx+xx=3/8*49/(3/8*49+0.5*40)= 0.48

Drop: xx/Jxx+xx=0.5*40/(3/8*49+0.5*40)= 0.52

 

SO the drop is better

 

The reason the sim probably over-represeted is that these calculations do not accurately reflect the fact that some hand pattern are more common than others. The sin gave vastly more 2425 hands than you would predict from using the a-prior suit% in this way. Its also possible that the sim results were not enough hands to be statistically significant, and hence overrepresented the drop, but I cba doing any more since I have to count them by hand.

[bluejak]

I carefully split up Phil's post and responded to each bit separately. You've taken one of my responses and put it beneath something from an entirely different post, as though I had been responding to that.

That is solely because the software does not allow me to copy direct.

 

But it is the bit you were referring to about four card overcalls showing strength. I am quite sure it is what you were responding to.

 

Ok, I shall copy it using copy and paste:

 

=============================================

Quote

 

4 card overcalls tend to imply a good hand, which means south would (barring an 8-2 club break) always have a t/o double if he has 3 spades.

 

I don't think anyone has posted anything in contradiction of that.

=============================================

 

 

Well, I haven't because I thought the whole analysis was irrelevant, not because I agreed with it.

 

I make four-card overcalls when I have a good suit that I want led, and am especially likely to make them when I have nothing else I want led. So in my case I would be unlikely to have either club honour.

 

But I do not see its relevance to the thread.

 

 

=====================

 

Happy now?

[jallerton]

All this discussion about the best line for a declarer who has been paying full attention is interesting from a declarer play point of view, but is of little relevance to the ruling.

 

The actual declarer claimed the rest of the tricks without stating a line, (presumably) believing that the rest of the tricks were obviously his.

 

Let's look again at the exact wording of Law 69B.

 

B. Director’s Decision

 

Agreement with a claim or concession (see A) may be withdrawn within the Correction Period established under Law 79C:

 

1. if a player agreed to the loss of a trick his side had, in fact, won; or

 

2. if a player has agreed to the loss of a trick that his side would likely have won had the play continued.

 

The board is rescored with such trick awarded to his side.

 

What does "if a player has agreed to the loss of a trick that his side would likely have won had the play continued" mean?

 

The "had play continued" is clear enough. If play had continued, this particular declarer would still have been at the helm; hence my earlier suggestion that the TD should attempt to ascertain the player's state of mind when he claimed.

 

But what is meant by the word "likely" in the context of "would likely have won"?

 

One problem here is that the word "likely" is normally used as an adjective often preceded by "very", "quite", "more" or "less", but in this Law 69B2 sentence it has been used as an adverb on its own. Chambers English Dictionary says that the use of "likely" in this way is slang [not good for a formal document!]. Another English dictionary says that "likely" is used as an adverb in American English, so I have delved into my foreign language dictionary collection and looked in Websters. According to Websters "likely" as an adverb means "probably"; "probably" itself is defined in Websters as "in all probability; so far as the evidence shows; presumably".

 

My conclusion from all of this is that the TD should only transfer a trick which would probably (which implies a significantly greater than 50% chance, say 70%-99%) have been won by the non-claiming side had play continued. If there is judged to be a (say) 55% chance, that is not enough.

 

Interestingly, Law 69B2 would not appear to allow the TD to transfer a trick which he is 100% sure would have been won by the non-claiming side: "would definitely have won" does not appear to be a subset of "would likely have won" and 69B1 seems to refer to tricks which had been completed before the claim. But I may have misunderstood; I can't believe that this is what the lawmakers intended.

[Cascade]

My conclusion from all of this is that the TD should only transfer a trick which would probably (which implies a significantly greater than 50% chance, say 70%-99%) have been won by the non-claiming side had play continued. If there is judged to be a (say) 55% chance, that is not enough.

 

I am not convinced. I think that something that is more than 50% is probable or likely.

[Echognome]

I'll muddy the waters even further. In statistics, the usage of "likely" is a derivative of "likelihood", which I believe to be synonymous with "probability". Here's a quote from a statistics book:

 

"There are six faces on a die, and on a fair die each is equally likely to come up when you throw the die."

 

Here, the likelihood of each event is 1/6. The term "equally likely" can be viewed as "having the same odds" or "having the same probability".

 

I agree that it would have been much clearer if there was a more descriptive phrase, such as "more likely than not". But there isn't and it is gray.

 

I will throw my own interpretation in with Wayne's. Another way to view "equally likely" is "equally probable". And if the law book read "would probably won the trick" then I associate that phrase as having a meaning of the cumulative probability of being greater than 50 percent.

[jallerton]

Imagine that you are playing a head-to-head match against team A tomorrow. You rate your opponents as significantly worse than your team. In probability terms, you rate your probability of winning the match as 75%.

 

Imagine that you are also playing a head-to-head match against team B the day after tomorrow. You rate these opponents as almost, but not quite, as good as your team. In probability terms, you rate your probability of winning as 51%.

 

If I ask you if you are going to win your match against team A tomorrow, you might well answer: "Probably".

 

If I ask you if you are going to win your match against team B the day after tomorrow, you might well answer: "Maybe", "Possibly" or "About 50-50". But you would not say "Probably", would you?