[awm]

 FM75, on 2014-July-03, 16:46, said:

For the most part, I agree. But a data scientist would strongly object to their publication.
1) They do not supply their data for independent review.
2) Their experiments are not "repeatable" (exactly) - can't reproduce the exact deals that they used.
3) Their experiments are not "repeatable" (even approximately), because they do not specify the constraints imposed on the deals.
4) They do not compare their results properly against a "null hypothesis". Was it better than the alternative - with respect to both correct predictions as well as false positives and negatives? By how much?
I laud the approach. I have criticized elsewhere the poor proof-reading - and obviously the errors missed in the second publication.

Kudo's for a scientific approach to the problems.

1. There is no set of established journals or conferences on bridge theory. We, the bridge community, are the independent review.
2. Their experiments are repeatable; running double dummy sims is easy to do on your own. This is often the case with processes which are somewhat random -- you won't get the exact same result, but the long-term trends should be the same. Further, I don't think an exhaustive list of their coin flips (deals) is particularly useful in examining an analysis of a stochastic process, nor do I find that such listings are typically provided in academic papers.
3. They do specify the constraints on the deals in the books, at least in most cases.
4. I am not sure what "alternative" you want; it is not like opening leads are an exact science or follow established rules. At various points they do state null hypothesis (lead 4th from longest and strongest, lead top from three touching honors but low from two touching honors) and show that these are incorrect.

[whereagles]

Well, I'm not even sure talking about "null" or "alternative" hypothesis makes any sense for the leads. (In the classical, statistical sense of the term.)

It would make some sense for evaluating reliability of DD analysis:

H0: "DD play yields the same average amount of tricks of single dummy expert play." versus
H1: "The average amount of tricks is different DD vs SD."

[the hog]

 jallerton, on 2014-July-02, 16:17, said:

If, like sfi, you have discussed your leading style with partner than you have an explicit partnership understanding. If you have played with someone for a while and notice what they tend to lead in certain situations then you have an implicit partnership understanding. Laws 40A1b and Law 20F2 imply that these understandings should be disclosed to the opponents.

If you know that your partner has an aggressive style of overcalls, you would disclose that fact to the opponents, would you not? If you know that your partner has an aggressive style of opening leads, why is that any different?

There are times when a truly idiotic post is made in these fora and this is one of those times. You open 1c and my pd overcalls 1s say on aqxxx and out. You expect me to alert for this? What a joke, the overcall is just bridge to me.I don't know whether these posts are made in some misguided way to show how ethical one pretends to be or whether they are just made in ignorance, but they are worthy of ignoring just the same.

[helene_t]

 the hog, on 2014-July-12, 06:21, said:

You open 1c and my pd overcalls 1s say on aqxxx and out. You expect me to alert for this?

Was anybody talking about alerting? I thought it was about disclosure in general, not necessarily alerting. Even if light overcalls are not alertable under your local regulations, I suppose you will tell your opps if they ask about it. Some CC templates have room for overcall style btw.

[the hog]

"Disclose that fact to the opponents" looks like alerting to me. Perhaps some players even want to alert the colour of their knickers?

[blackshoe]

 the hog, on 2014-July-12, 17:28, said:

"Disclose that fact to the opponents" looks like alerting to me.

Perhaps you need glasses.

[the hog]

 blackshoe, on 2014-July-12, 17:51, said:

Perhaps you need glasses.

Perhaps you need a brain? Certainly some shoe polish is required.

[barmar]

Whether an agreement is alertable is up to the RA. ACBL's Alert Procedures says; "Treatments that show unusual strength or shape should be Alerted." So the only question is whether a simple overcall with AQxxx and out is considered unusual.

[blackshoe]

 the hog, on 2014-July-12, 19:37, said:

Perhaps you need a brain? Certainly some shoe polish is required.

Well played, oh master of the Flame.

[gordontd]

 the hog, on 2014-July-12, 17:28, said:

"Disclose that fact to the opponents" looks like alerting to me.

My opponents ask about our overcall style and I tell them it's very sound at the two level. That's disclosure but not alerting.

[the hog]

 gordontd, on 2014-July-13, 02:37, said:

My opponents ask about our overcall style and I tell them it's very sound at the two level. That's disclosure but not alerting.

Yes, I totally agree with this and if they ask I am more than happy to explain, Gordon, but re read JAllerton's post and you will see why I am making this point.

[gordontd]

 the hog, on 2014-July-13, 02:44, said:

Yes, I totally agree with this and if they ask I am more than happy to explain, Gordon, but re read JAllerton's post and you will see why I am making this point.

I don't see it like that Ron. I think Jeffrey is making the point (correctly in my view) that quite a lot of players are less likely to fully disclose their understandings about lead styles than they would be about their bidding styles.

[GreenMan]

The posts demanding disclosure said nothing about "if asked." Looking at the posts they were replying to, I can come to no conclusion except that they want "disclosure" to come unasked.

Something like "We don't always lead 4th Best from our Longest and Strongest against notrump"?

Or "We lead our suit unless we think we should try to hit partner's suit, or we decide a passive lead is called for."

If this sort of thing requires pre-alerting then the world has gone mad.

[the hog]

 GreenMan, on 2014-July-14, 20:54, said:

The posts demanding disclosure said nothing about "if asked." Looking at the posts they were replying to, I can come to no conclusion except that they want "disclosure" to come unasked.

Something like "We don't always lead 4th Best from our Longest and Strongest against notrump"?

Or "We lead our suit unless we think we should try to hit partner's suit, or we decide a passive lead is called for."

If this sort of thing requires pre-alerting then the world has gone mad.

Thank you. That is what I was saying.

[gordontd]

 GreenMan, on 2014-July-14, 20:54, said:

If this sort of thing requires pre-alerting then the world has gone mad.

We don't have pre-alerting here (where jallerton is posting from), or rather it takes the form of properly filling out the convention card and my guess is that is what he is asking for, as well as full explanations when asked.

[helene_t]

 the hog, on 2014-July-15, 00:33, said:

Thank you. That is what I was saying.

Great. So we all agree. Now we can get back on topic.

[GreenMan]

 gordontd, on 2014-July-15, 01:18, said:

We don't have pre-alerting here (where jallerton is posting from), or rather it takes the form of properly filling out the convention card and my guess is that is what he is asking for, as well as full explanations when asked.

The CCs I'm familiar with only note which card is led from the suit selected -- things like 4th vs 3rd/5th best, which honor from a sequence, which card from three or four small, etc. They say nothing about which SUIT one leads.

Until the CC has a box for "4th best from longest and strongest vs. NT [ ]Always [ ]Not Always" then that's not any sort of solution. Though I remain unconvinced that there's even a problem.

[helene_t]

 gordontd, on 2014-July-13, 03:59, said:

I think Jeffrey is making the point (correctly in my view) that quite a lot of players are less likely to fully disclose their understandings about lead styles than they would be about their bidding styles.

It's probably a lot more difficult to summarize partnership understanding about opening leads. Whether p choses a passive or an aggresive lead (and which leads would count as passive) in a given situation depends on so many factors. You may have a feeling that your p is a bit less aggresive that most other players but it is impossible to phrase this in a specific way, and hence won't be very helpful to opps. It isn't really meaningful to say that "he is more likely to lead dummy's second suit than to lead his own suit" because even if that may be true based on an over-all statistic, it may not be true after this particular auction.

Conversely, you can be quite specific about overcall style.

With one p I know that he almost never underleads unsupported kings and with another p I know that she very often prefers to lead a trump or dummy's first suit even if I personally don't see that the auction suggests such a lead. I would of course disclose that if asked. If playing with GIB against human opps who don't know GIB I would disclose his likeness for passive leads because it is so extreme. But with most partners I can be much more helpful if opps ask about their overcall style than if opps ask about their lead style.

[Mbodell]

So I read the nt book a few months ago and just finished the suit book at the start of nationals. So far, in my very small sample size the suit leads are big winners (both when I made them and when opps or partner failed to). I think the nt leads are winners too, but that isn't as clear. One thing that is clear is that playing some form of Smith is important when leading this style against nt.

[rhm]

 benlessard, on 2013-September-24, 22:04, said:

I believe that double dummy simulation are generally useful however leads is where I have the most doubt.
...

 Mbodell, on 2014-July-24, 02:19, said:

So I read the nt book a few months ago and just finished the suit book at the start of nationals. So far, in my very small sample size the suit leads are big winners (both when I made them and when opps or partner failed to). I think the nt leads are winners too ...

I am amazed.
Did I understand correctly?
Following recommendations derived from double dummy simulations lead to better results single dummy at the table ???
Something to think about for all those, who question time and again the validity of double dummy simulations.

Rainer Herrmann