Silly question about randomizing

[gnasher]

I do have a habit of trying to work out early in the course of a defence whether I will actually need to play equals in some random order; if so, I will use some external aid such as the vulnerability on a board - NV I will play low from QJ, VUL I will play high.

Haven't you rather diminished the value of that method by publishing the details on an internet newsgroup?

 

I recall once having to play from J109 when declarer held Axx and dummy KQ8x. Since there are six orders in which one can play those cards, I took the board number modulo 6 and selected what turned out to be the order 10-9-J. That jack fell under dummy's queen, of course, and declarer said "I knew you were trying to fool me by petering with 10-9 to show a doubleton".

Surely you only needed three numbers? It's OK to always play upwards; what matters is that the pair of cards be selected at random.

[pooltuna]

I do have a habit of trying to work out early in the course of a defence whether I will actually need to play equals in some random order; if so, I will use some external aid such as the vulnerability on a board - NV I will play low from QJ, VUL I will play high.

Haven't you rather diminished the value of that method by publishing the details on an internet newsgroup?

Yes but of course this assumes that this is the only method he uses to randomize I suspect he has several others and probably picks what comes to mind at the moment which is sort of random :)

[dburn]

I do have a habit of trying to work out early in the course of a defence whether I will actually need to play equals in some random order; if so, I will use some external aid such as the vulnerability on a board - NV I will play low from QJ, VUL I will play high.

Haven't you rather diminished the value of that method by publishing the details on an internet newsgroup?

Not necessarily, for future opponents will need to guess whether I am actually using the method as disclosed here, or whether I have reversed it so that I play low when vulnerable and high otherwise.

 

However, the thought occurred to me that the vulnerability might not be a sufficiently random datum in this context. I have no statistical data with which to verify this hypothesis, but I conjecture that on balance you are more likely to be defending when you are vulnerable than when you are not. No doubt there is someone here who does have the necessary data, and I should be interested in any findings.

[Jlall]

lol you don't have to even be close to 50/50 so you should be safe as long as you're not 100/0.

[Fluffy]

I do have a habit of trying to work out early in the course of a defence whether I will actually need to play equals in some random order; if so, I will use some external aid such as the vulnerability on a board - NV I will play low from QJ, VUL I will play high.

Haven't you rather diminished the value of that method by publishing the details on an internet newsgroup?

Not necessarily, for future opponents will need to guess whether I am actually using the method as disclosed here, or whether I have reversed it so that I play low when vulnerable and high otherwise.

 

However, the thought occurred to me that the vulnerability might not be a sufficiently random datum in this context. I have no statistical data with which to verify this hypothesis, but I conjecture that on balance you are more likely to be defending when you are vulnerable than when you are not. No doubt there is someone here who does have the necessary data, and I should be interested in any findings.

The biggest problem I see with this is that partner might be able to get UI if he knows it.

[gwnn]

One friend of mine told me 'oh I always play for the drop if the Q appears and ignore restricted choice, almost everyone drops the Q from QJ tight 90+% of the time', does anyone here follow this in weakish fields?

[Fluffy]

I have heard that argument before yes. But its not like people should play or the drop when the queen appears, what it means is you have a 95% when the jack appears by finesing. The others are almost equal then.

[Jlall]

One friend of mine told me 'oh I always play for the drop if the Q appears and ignore restricted choice, almost everyone drops the Q from QJ tight 90+% of the time', does anyone here follow this in weakish fields?

It's not worth it, you'd have to be really sure. The edge you gain is so tiny from doing this, compared to the potential loss you are incurring if you're wrong about their frequency.

 

edit: Not to mention if it's matchpoints do you really want to get a top every time it's QJ tight, and a bottom every time it's stiff Q? Even though you make a small gain in the long run, it's not worth it if you're one of the best pairs in the field. If it's a team game then do you want to risk win 13 or lose 13 on something that random...not if you're the better team. It's a small enough edge and big enough variance (because everyone will play restricted choice) to pass up.

[Little Kid]

One friend of mine told me 'oh I always play for the drop if the Q appears and ignore restricted choice, almost everyone drops the Q from QJ tight 90+% of the time', does anyone here follow this in weakish fields?

If my maths is correct they would have to make that falsecard over 91% to break even? I guess if the opponents are that predicable it works.

[MarkDean]

I am reasonably certain that people play the Q from QJ against me over 91% of the time. I started paying attention over a year ago, and only once has somebody played the jack. It was definitely a bigger sample than 11.

[cherdanno]

I guess it's a good opportunity to swing when you are down though.

[Mbodell]

Perhaps in honor of this thread I played the J from QJ-tight tonight.

[Fluffy]

Perhaps in honor of this thread I played the J from QJ-tight tonight.

did it work?

[Jlall]

Perhaps in honor of this thread I played the J from QJ-tight tonight.

did it work?

lol

[EricK]

I remember a time when I played the J from QJ and the declarer "accused" me of being tricky!

[pooltuna]

I remember a time when I played the J from QJ and the declarer "accused" me of being tricky!

Be delighted, be very delighted! This is a reputation you want your opps to have of your play as it increases their anti%age play.

[rwbarton]

Since I happen to have a sample of several million hands played on BBO handy, I thought I would do a study of how defenders play from QJ in real life. Of the first 66000 hands my program looked at where a defender held QJ tight, the defender played the Q first only 52% of the time. However, this includes situations such as the opening lead and when partner is leading the suit, and does not take into account the contract. Suggestions for better parameters for the study are welcome. I think I'll try only hands where QJ is in the trump suit next.

[jdonn]

Since I happen to have a sample of several million hands played on BBO handy, I thought I would do a study of how defenders play from QJ in real life. Of the first 66000 hands my program looked at where a defender held QJ tight, the defender played the Q first only 52% of the time. However, this includes situations such as the opening lead and when partner is leading the suit, and does not take into account the contract. Suggestions for better parameters for the study are welcome. I think I'll try only hands where QJ is in the trump suit next.

Can you restrict to only times when the opponents lead the suit to that trick?

[cherdanno]

Truly bad players will always play the J. I think we are talking about "good" players here, i.e. players who are good enough to try to do something tricky.

 

Btw, I just wanted to mention that I am completely exploitable and always play the Q.

[helene_t]

Truly bad players will always play the J. I think we are talking about "good" players here, i.e. players who are good enough to try to do something tricky.

 

Btw, I just wanted to mention that I am completely exploitable and always play the Q.

That's the optimal strategy if opps think you are a noob.

 

Then again, if opps think you think they think you are a noob, you should always play the jack ;)

[eyhung]

I randomize by using a similar technique I learned from poker -- glancing at my digital watch and looking at the final seconds digit when I can anticipate a later decision (obviously not when i'm about to play.) Odd is one direction, even is another. I think this is unexploitable even if known, especially if I wear sunglasses.

[campboy]

That sounds illegal to me. Law 40C3a.

Unless permitted by the Regulating Authority a player is not entitled

during the auction and play periods to any aids to his memory,

calculation or technique.

[rwbarton]

Since I happen to have a sample of several million hands played on BBO handy, I thought I would do a study of how defenders play from QJ in real life.  Of the first 66000 hands my program looked at where a defender held QJ tight, the defender played the Q first only 52% of the time.  However, this includes situations such as the opening lead and when partner is leading the suit, and does not take into account the contract.  Suggestions for better parameters for the study are welcome.  I think I'll try only hands where QJ is in the trump suit next.

Can you restrict to only times when the opponents lead the suit to that trick?

I ran the study using this rule, which I took to mean "consider instances where a defender held QJ in a suit, and the first of those cards was played following suit to declarer or dummy's lead", and I also eliminated cases where the defender was GIB.

 

Among my sample of BBO hands, there were more J plays than Q plays: 59.1% of the time the J was played (out of 74703 instances). I also grouped the instances by BBO username. For instance, among the 339 people who faced the problem exactly 6 times, there were

 

23 people who played the J 0 times (always the Q),

27 people who played the J 1 time,

51 people who played the J 2 times,

51 people who played the J 3 times,

49 people who played the J 4 times,

65 people who played the J 5 times,

74 people who played the J 6 times.

 

It's hard to make any solid conclusions from this data, but it looks like there are a lot of players who always play the J, some players who always play the Q, and some players who play randomly. (Again, this is from my utterly unscientific sample of hands played on BBO.)

[jdonn]

That sounds illegal to me. Law 40C3a.

Unless permitted by the Regulating Authority a player is not entitled

during the auction and play periods to any aids to his memory,

calculation or technique.

What he is doing definitely doesn't aid "memory" or "calculation". I don't think it aids "technique" either though you could argue that one (to me that sounds more like having a book on your lap explaining compound squeezes). I think it just aids "strategy", which is not mentioned.

[cherdanno]

I ran the study using this rule, which I took to mean "consider instances where a defender held QJ in a suit, and the first of those cards was played following suit to declarer or dummy's lead", and I also eliminated cases where the defender was GIB.

 

Among my sample of BBO hands, there were more J plays than Q plays: 59.1% of the time the J was played (out of 74703 instances). I also grouped the instances by BBO username. For instance, among the 339 people who faced the problem exactly 6 times, there were

 

23 people who played the J 0 times (always the Q),

27 people who played the J 1 time,

51 people who played the J 2 times,

51 people who played the J 3 times,

49 people who played the J 4 times,

65 people who played the J 5 times,

74 people who played the J 6 times.

Waiting for Helene to tell us how often we have to see someone play the Q from QJ until it is worth trying exploit his tendency.