BBO Discussion Forums: Why do people play 15-17 over 14-16 w/T-Walsh - BBO Discussion Forums

So the European championships had a large number of playing 15-17 NT range with T-Walsh.

This doesn't seem to make a great deal of sense to me - from my experience a key advantage of the method is being able to play with an optimally spaced NT ladder of 11-13, 14-16, 17-19. I don't see what the downside is other than sometimes playing against the room if you are playing matchpoints. Two likely hypothesis that occur to me are: Most of those people playing 15-17 are aggressively upgrading 14 counts and it's really (14)15-17, or the matchpoints thing is really valuable.

Am I missing anything? Why would you play a 15-17 NT with T-Walsh?

Maybe they disagree whether 11-13, 14-16, and 17-19 are optimally spaced. They are evenly spaced into three 3-point ranges, but because of frequencies, that might not be optimum.

If you're trying to split on the basis of frequency, wouldn't that argue going for tighter definition at the lower end, which are by far the most frequent hands? I can see where you are coming from, but I'm not sure why that suggests splitting into 11-14, 15-17 and 18-19.

The rationale for the 18-19 as I understand it is that you had to rebid 2NT and then you have a serious lack of room.

Cthulhu D, on 2014-September-29, 18:13, said:

Yep, that's why I like tight at the high levels...lack of room. I don't mind 11-14 at the bottom, because of all the toys and room we have for sorting things out ---xyz, NMF, checkbacks, whatever.

What confuses me is the pairs with an 11-13 pt. bottom who still commit to game on all non-fitting 12's after 1 of a suit is opened, whether there is a 1NT rebid or not.

IMHO, the 17's and the 22's should be judged on merit for bumping up into the next category --but, not the 14's. That probably just means I am old.

Maybe they are like me and don't think opening balanced 11s is good tactics. This is not to say that there aren't occasional "really good 11s" that get upgraded into opening bids, but if you're not opening most 11s it doesn't really make sense to have an 11-13 range.

Playing a different NT range than the field is definitely an issue. Also, some of them might be playing that a transfer completion shows 3 cards, in which case they still need to jump to 2NT with 18-19.

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Yeah, having opened balance 11 counts since day 1, a bad 12 count is only worth an invite definitely.

mgoetze, on 2014-September-29, 19:54, said:

Aha! This is it - a number of the pairs playing 15-17 have transfer completion show 3 cards (edit, though not it appears the majority? who knows) Thank you for clarifying that mystery. This raises a new question though - I wonder what the practical merits of each is? The sample size is probably to small to make a pragmatic conclusion. The previous threads on this topic favour transfer acceptance = Weak NT.

awm, on 2014-September-29, 19:19, said:

mgoetze, on 2014-September-29, 19:54, said:

I suspect that these are the two main reasons.

A third reason may well be that most pairs are not system-geeks and prefer to play what they are comfortable with, even if it is not optimal.

Sometimes you end up too high with 17 when the field is in 1NT passed out. Either in game when you find a 4-4 fit or in 2NT when responder bids 1♠ or 1NT.

Double Post

gwnn, on 2014-September-30, 01:17, said:

This and PaulG's response make a lot of sense.

Has anyone done a reliable study on the costs/merits of opening light? It seems clear that opening balanced 10 counts is losing bridge, and aggressive 1S openings are losers, but Richard Pavlicek's analysis lead me to conclude that opening any other 11 count was winning bridge.

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Pfft, weakness! More seriously though, I considered this and thought that switching to T-Walsh shows SOME measure of geekery, and certainly adapting your 1NT range is a small cost that if you are willing to play T-Walsh would be a small marginal change, so I figured this was not the root cause.

Cthulhu D, on 2014-September-30, 01:25, said:

Can you provide a link to the page of Richard Pavlicek's analysis, from which you concluded that opening balanced 11 HCP hands is winning Bridge?

I know analyses where one room passed and the other opened the bidding with 1♣/1♦/1♥/1♠, but this was not constrained to balanced 11 HCP and Pavlicek's conclusion about mini notrump was not particularly positive.

Rainer Herrmann

rhm, on 2014-September-30, 05:13, said:

You've obviously read it - it's the opening 1NT vs Pass and opening 1C vs Pass (here: http://www.rpbridge.net/rpme.htm). When I looked at the hand records provided it *seemed* (I have not performed a detailed statistic analysis, this was just my conclusion), that 10 HCP hands were causing the swing towards pass for NT (this was not a strong trend), and in the 1C sample a huge number of the variant hands that are causing a swing towards opening 1C over pass are people opening balanced 11 counts - this was a *very* significant trend. It's worth noting as well that he's very positive about a weak no trump - the weak no trump consistently does better than the strong NT.

Just looking at for example the first 7 bids in the 1C vs Pass. 6 of them are opening a 1C in a short club system, and one is opening an unbalanced 10 count. The 6 balanced 11 counts all go plus, the unbalanced 10 count goes minus. I did a more robust review when I was examining my opening style, but nothing formal (I looked at just pass vs 11 count hands and added up the imps for them). The lack of a comprehensive study though was why I asked this question! I would be fascinated if anyone has more robust analysis. I could very well be wrong - but that is the lesson I took from the trends on those two bids.

Even if you have methods to show the strong balanced hand with a 1NT rebid, there are still advantages of not having the 17 counts in the 1♣ opening as you presumably will be more or less obliged to reopen after a preempt which isn't safe.

Besides, if the 1NT rebid is 17-19 you have to rebid 2NT with 20. In Polish Club, the 1NT rebid is 18-20 as well.

Cthulhu D, on 2014-September-30, 05:29, said:

You have to be careful about what you conclude! The 1NT versus pass figures, for example, are not so clear cut at all with 1NT showing a marginal gain at IMPs and pass definitely coming out on top in the win/loss/tie ratio. Also, using the 1C vs pass figures, which seem to suggest bidding (as you point out) in turn would imply you're probably playing a stronger NT range, but Pavlicek's numbers suggest that weak NT (compared to opening 1m) is better than strong NT (versus 1m).

As ever with these things you have to consider the overall effect on the whole system - which is often *very* hard to quantify.

Nick

I think the reasons for using 15-17 have been mentioned already, but I think 14-16 is optimal together with T-W. When I play like that I do not open 1♣ with 11 (unless it is an upgrade to 12). This means that the most common balanced range (12-13) is more accurately bid.

The problem that Adam mentioned with getting too high with 17 can be reduced by splitting up 17-19 into two parts. And then you might as well combine it with 20-21 balanced. What I mean is that 1♣-1R-1M is either 12-13 or 19-21, and 1♣-1R-1NT is 17-18. 19 feels like a GF against a 1-over-1 response, while 17-18 is not it, so I like this a lot. Starting low with 20-21 balanced is also good. Typically you do 1-over-1 with 5 points anyway, and missing games with 21+4 is not too bad (21 balanced against any hand with 4hcp makes 3NT only about 45% of the time), so you can play like this without big changes (except you need to play 1♣-1R-1M as almost forcing, and agree on how to show 19-21 balanced later on in the bidding). And naturally you also win by freeing the 2NT opening for something else than 20-21 balanced.

One reason could be 17-19 balanced with a five card major. When I played T-Walsh I thought that 1M-1X; 2NT was a pretty poor auction. Actually I also thought that 1♣-1red; 3red (which for us showed 17-19 balanced and 4 card support for the major) was an awkward auction sometimes since responder could not invite.

paulg, on 2014-September-30, 01:06, said:

Cthulhu D, on 2014-September-30, 01:25, said:

I agree with Paul here. Many top players are more interested in card play and bidding judgement, rather than designing bidding systems. Certain methods tend to become popular in particular countries/regions. This is hardly surprising, as most players pick up methods from people they regularly play with and against.

helene_t, on 2014-September-30, 05:31, said:

Not quite. If the 1NT rebid is 17-19, you have to open 2NT with 20.

One of the advantages of playing transfers over 1♣ and using the completion to show a weak NT is that 2NT rebid is not needed in a natural sense so can be used to cater for something else, e.g. good hands with 6 clubs, certain raises.

NickRW, on 2014-September-30, 07:45, said:

Sure, but in this case I think you are drawing conclusions from inappropriate data sets. Many boards in the 1NT vs Pass analysis are people opening 9 HCP hands or 10 HCP hands. Those are not interesting when the question is 'do we open balanced 11 counts' you must go into the underlying data - which significantly impacts the sample sizes, and makes the conclusion very questionable - to consider only the 11 HCP hands.

Similarly for the 1C vs Pass analysis, again, we need to consider only balanced 11 counts because that is the question we are asking (is it right to open balanced 11 counts). There are a bunch of 9 and 10 counts and some unbalanced 11 in there, and they need to be tossed to answer the question.

Just using Pavlicek's top level numbers for this will not work because the underlying datasets do not align with the question we are trying to answer.

My limited analysis of the dataset is favourable for opening balanced 11 counts (but not 10 counts! Important!). I could be wrong. I would like a more comprehensive examination. I would also be interested to know the cost of opening a short 1C vs a better minor 1D and the benefit from an unbalanced 1D (which is very hard to answer). I would also love to see what the numbers on a 11-13 1NT looks like - it is very possible that is the 'optimal' (airquotes) NT range.

I'm (relatively) confident in this analysis because it reflects my reflects my at the table experience, but I could very well be wrong.

Cthulhu D, on 2014-September-29, 17:42, said:

Your first hypothesis is definitely true. A lot of 14-counts get opened a strong NT. Some pairs put (14)15-17 on their convention card; others choose not to disclose it (when challenged some will tell you that it's "just bridge"). Of course, players at this level are not strict point counters (which is one reason why the results of computer analyses need to be treated with caution) but in my experience "upgrades" are at least ten times as common as "downgrades".