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no trump hand evaluation methodology

#21 User is offline   jogs 

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Posted 2016-July-19, 07:00

View PostLiversidge, on 2016-July-17, 11:10, said:

I will be very interested to read the answers to this question.
Last week partner and I had two hands where we opened a weak 1NT with Axxx AJx Axx xxx (me) and Axxx AJx Axx Jxx (partner). Both went off and we got a bad score. Partner said his normal rule is not to open 1NT with nine losers but he reluctantly broke his own rule because he had 14 HCP, and says he won't do so again.
I am not sure.. I would open with AJT8 AT9 A97 xxx any vulnerability but would probably pass with A653 A83 AJ2 J76 if vulnerable, but await comments.

Blame acol and weak notrumps. Aces tend to be more valuable in suit strains than notrumps.
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#22 User is offline   NickRW 

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Posted 2016-July-19, 07:04

View Postrhm, on 2016-July-19, 06:19, said:

How any serious player can believe that 2 jacks and a ten are equivalent to an ace escapes me even for notrump contracts.


I don't disagree. I was trying to be nice. Perhaps I shouldn't have been.

Nick
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#23 User is offline   fromageGB 

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Posted 2016-July-19, 07:14

View Postjogs, on 2016-July-19, 07:00, said:

Blame acol and weak notrumps. Aces tend to be more valuable in suit strains than notrumps.

This is an under-emphasised point. System is very important. Playing a strong NT I will be delighted to open 1C on 3 bare aces (OK, I expect there will be 10 other cards) as it is so much more likely to end in a part score suit contract. If I was (very rarely) playing a weak NT, I would be reluctant to open, as the weak NT preempts partner from bidding. I'll probably pass.
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#24 User is offline   blackshoe 

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Posted 2016-July-19, 14:34

I tend to use Marty Bergen's methods:

1. "Starting points": count your HCP. Adjust-3 (sum of # of aces and tens - sum of # of quacks. If this is +3 to +5, add a point. If it's +6 or more, add two points. If -5 to -3, subtract a point, if -6 or less subtract two points). Add a point for each card over five in a suit. Add a point for a good suit (4 or more cards, 3 honors), two points for a great suit (five or more cards, four or more honors). Subtract a point for each dubious singleton (K, Q, J) or doubleton (KQ, KJ, QJ).

2. "Dummy points": when raising with an eight card or better fit, add a point for each doubleton, three points for a singleton, and your # of trumps for a void to your starting points.

3. "Bergen points": when partner shows a fit, add a point for two doubletons, two points for a singleton, three points for a void to your starting points.

When we have a fit I often switch to losing trick count or "cover cards".
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#25 User is offline   rmnka447 

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Posted 2016-July-19, 14:37

For me, determining the appropriateness of opening a hand at the one level starts with QTs/defensive tricks. Hands with 2 QTs that meet the other requisities for an opening bid will normally be opened. Hands with 3 or more QTs will always be opened. Hands with 1 QT or less are never a 1 bid.

For a NT bid, a hand needs the QTs along with the prescribed HCPs for the NT bid. Playing weak NT, as I often do, then 12 HCP and 2 QT in a balanced/semi-balanced hand are enough for 1 NT. The only exception is opening 1 NT with an 11 HCP 3 QT hand (which has to be AK in one suit and an A in another suit.) With 5-4-2-2 semi balanced hands, I'm looking where the points are concentrated. If they are concentrated in the long suits, I treat the hand as unbalanced and open in a suit (xx KQxx xx AKxxx). While if the points are concentrated in the doubletons, I treat it as balanced and open 1 NT (KQ Kxxx Ax Jxxxx). Since 12 HCP is the floor for a weak NT, except for the aforementioned exception, I don't usually open 2 1/2 QT 11 HCP hands 1 NT.

Typically, I don't make too many adjustments for flaws/features, such as doubleton honors, but may if other factors in the hand make opening the hand borderline ( Pass - K432 KQ J753 K63, open 1 NT - K1064 KQ 865 KJ82, pass - A64 A85 K754 983, open 1 NT - 86 A108 AQJ109 1062).

For 1 of a suit bids, I'm a tad more flexible. I'll open 2 1/2 QT with 11 or 1 1/2 QT hands with 13+. I'll make adjustments for plus/minus evaluation factors. I'll also definitely open any rule of 20 hand with 2 QTs and occasionally some with less ( open 1 C - x x KJ10xx KQ10xxx, open 1 C - Qxx QJx x AQJ109x).

My experience has been good with this approach over many years resulting in winning a lot of masterpoints. There's no perfect answer because people do have different bidding styles and sensibilities. However, pick a starting spot and monitor your results from there.
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#26 User is offline   helene_t 

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Posted 2016-July-19, 15:10

4-3-2-1 is actually surprisingly accurate when it comes to the decision to bid 3nt or not. I made a logistic regression analysis of the GIB DD database and found that the coefficients, when the outcome variable is "3nt makes DD", are very close to 4-3-2-1. Of course colaborating honours, tens and nines, and honours in long suits matter a bit. But devaluating aces (as in Banzai) or upvaluating aces (as in Viena points) will make it worse.
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#27 User is offline   msjennifer 

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Posted 2016-July-19, 18:03

Playing a weak no trump,it is unwise to open a flat 4333 hand with 3Aces as 1NT.Same applies when two suits are wide open.Playing a standard system, and Red vs White ,one International opened 1 NT holding xxx,AKQx,AKJx,xx .All Pass.Going 3 down and minus 300 got the zero it deserved in the match point pairs.True, the opponents were making 3S. Now is it bad luck or unwise opening bid ?All others opened the hand 1 D and opponents played in spade partials..Using a rule of 20 or any other number does not help when opening a hand as 1 NT.A 1NT is passed out if partner holds a flat 6/7 HCP and goes down when a contract of two In a 4/4 suit is on ice if one had opened the hand 1C/D.
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#28 User is offline   Stephen Tu 

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Posted 2016-July-19, 18:20

View Postmsjennifer, on 2016-July-19, 18:03, said:

Playing a weak no trump,it is unwise to open a flat 4333 hand with 3Aces as 1NT.Same applies when two suits are wide open.Playing a standard system, and Red vs White ,one International opened 1 NT holding xxx,AKQx,AKJx,xx .All Pass.Going 3 down and minus 300 got the zero it deserved in the match point pairs.True, the opponents were making 3S. Now is it bad luck or unwise opening bid ?All others opened the hand 1 D and opponents played in spade partials..

Well the question that would come to my mind is how many of the others were strong NT pairs. Next time the auction might go 1d-p-1s-p, then what? 2H? 2nt? To me any choices can work out badly on a single hand, to really prove that it's unwise to open 1nt with 2 suits wide open you'd really have to do it statistically over a whole bunch of different hands.
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#29 User is offline   jogs 

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Posted 2016-July-19, 18:37

View Postmsjennifer, on 2016-July-19, 18:03, said:

Playing a weak no trump,it is unwise to open a flat 4333 hand with 3Aces as 1NT.

A432 A32 A32 432
Do you plan to pass? Or open 1 planning to pass 1NT, raise 2 or 2, and rebid 2 after 2.
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#30 User is offline   rhm 

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Posted 2016-July-20, 02:09

View Posthelene_t, on 2016-July-19, 15:10, said:

4-3-2-1 is actually surprisingly accurate when it comes to the decision to bid 3nt or not. I made a logistic regression analysis of the GIB DD database and found that the coefficients, when the outcome variable is "3nt makes DD", are very close to 4-3-2-1. Of course colaborating honours, tens and nines, and honours in long suits matter a bit. But devaluating aces (as in Banzai) or upvaluating aces (as in Viena points) will make it worse.

I see some contradiction to Thomas Andrews research.
He claimed that the best coefficients for notrump were from Ace to Ten:

A=115
K=74
Q=43
J=23
T=10

He attaches also a double dummy value to the 9 (=4) and 8 (=2).

So according to Andrews Double Dummy analysis

An ace is equivalent to

Ace = 1.5 Kings = 2.7 queens = 5 jacks

Compare this to standard point count

Ace = 1.33 kings = 2 queens = 4 jacks

Of course the above coefficients are not practical, but they show that the ace is undervalued even at notrump and at least my double dummy studies tend to confirm this.

The fifth evaluator A=4 K=2.8 Q=1.8 J=1 T=0.4 is somewhere in between, more practical and considered more accurate than standard HCP. It also values the ace indirectly higher by reducing the value of king and queen and making room for the Ten within a total of 40 HCP per deal.

Rainer Herrmann
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#31 User is offline   Zelandakh 

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Posted 2016-July-20, 02:51

View Postrhm, on 2016-July-20, 02:09, said:

A=115
K=74
Q=43
J=23
T=10

Let's normalise this by multiplying through by 3/74. Then:-
A = 4.66
K = 3
Q = 1.74
J = 0.93
T = 0.4

That gives a good basis for the idea of upgrading aces by (at least) half a point. What is missing from the analysis of the lower honours is whether they are with higher honours or alone in a suit. My opinion is that there is a big difference between the ten in AJTxx and Txxxx. Similarly, as Helene mentioned, being in a short suit devalues them further. So my method is to count the quacks as full value with a higher honour but 0.5 points less if alone; the Bergen evaluation that Ed gave, effectively discounting quacks by 0.3, is also fully justified. For a ten, counting it as 0.5 unless alone looks like it would work well (based on these numbers).

To the nearest half a point, the coefficients given are 4.5 - 3 - 1.5 - 1 - 0.5, which look rather familiar! Of course that 1.74 for a queen is annoying as it falls between 2 data points. We could double the values to give:-
A = 9.32
K = 6
Q = 3.49
J = 1.86
T = 0.81

To the nearest half integer, 9.5 - 6 - 3.5 - 2 - 1. Hmmm, too complicated? How about normalising to a K = 4 points:-
A = 6.22
K = 4
Q = 2.32
J = 1.24
T = 0.54

That is, A = 6, K = 4, Q = 2.5, J = 1, T = 0.5. That looks fairly good - perhaps in the future this is a method that could take off, even more so if we used Q = 2 and add half a point for an accompanied queen. What is very clear from these numbers is that the theoretical basis of Banzai points, which devalue aces relative to kings and quacks, is highly questionable. That is even more the case when one considers that a trump contract is still possible, as mentioned earlier by Rainer. I think the only reason for mentioning Banzai points in N/B is to warn readers not to use them!

The best way of evaluating though is more of an open question. I suspect that many different methodologies are used at expert level but almost all of them end up roughly in the same place. I suspect it would advance bridge theory somewhat for someone to do the work to implement a knowledge-based system, in the same way that doing this for positional analysis in chess created a revolution in computers and eventually in master play itself.

What I disagree with is jogs' assertion that we should be calculating directly in tricks. What should be obvious from the numbers in this post is that using points allows for far more flexibility in design while arriving at the same result. I am confident that this basis will remain for regular evaluation. Feeling constrained to use only tricks is useful only for creating something simple (and usually poor) for low level players or for those that do not understand the maths. It is almost always the case that a trick-based system can be improved by converting to points while retaining enough simplicity to be useful.
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#32 User is offline   helene_t 

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Posted 2016-July-20, 03:56

As far as I can see on Thomas Andrew's site he gets the same results as I when he adresses the question of bidding 50% games. When he requires 40% he values the aces more aggresively, close to the numbers Rainer quoted.

There could be small discrepancies due to differences in subset selection ( I excluded hands with which we were obviously not aiming at a notrump contract, i.e. 9-card major suit fits and such but I don't remember the details). I also assumed that declarership was randomized, I think he does the same but obviously one could argue that a strong balanced hand should be assumed to be declarer most of the times as standard bidding systems tend to achieve that.

It is intriguing that aces should carry more weight when aiming at a 40% game than a 50% game. Intuitively I would think that the coefficients would be similar just the threshold different.

BTW the queens are valued less than two jacks. I suspect this is due to queens being slightly less valueable DD than SD because it doesn't matter that you are missing the queen as long as you have a 2-way finese since you always get the two-way finesse right. If my hypothesis is correct, bridgebrowser should value queens more favorably than GIB does. I have some bridgebrowser data, I will have a go with that next week.
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#33 User is offline   Zelandakh 

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Posted 2016-July-20, 04:45

View Posthelene_t, on 2016-July-20, 03:56, said:

It is intriguing that aces should carry more weight when aiming at a 40% game than a 50% game. Intuitively I would think that the coefficients would be similar just the threshold different.

I suspect this is because very thin games are sometimes makeable only by holding up and hoping for a certain break whereas 50% games often have a power line or avoidance play to reduce the premium of this aspect of an ace. It would take a proper analysis of the data though to say for sure what is going on there.
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#34 User is offline   rhm 

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Posted 2016-July-20, 05:36

View PostZelandakh, on 2016-July-20, 02:51, said:

Let's normalise this by multiplying through by 3/74. Then:-
A = 4.66
K = 3
Q = 1.74
J = 0.93
T = 0.4

Normalizing can be done in different ways, but I think the right way to normalize for comparison with standard HCP is to normalize so that the sum of the top 5 honors are equal to ten, so that the whole deal remains at 40 points.

This gives you the following results:

A=4.3
K=2.8
Q=1.6
J=0.9
T=0.4

Again you see aces are worth more and and quacks are worth less.
In suit contracts the spread is higher.

I do not know whether somebody has created a point count on this but it could be done fairly easily.

A=11
K=7
Q=4
J=2
T=1

This gives you 100 HCP per deck. A king plus a queen equals an ace, and a queen plus a jack and a ten equals a King.
Ballpark figures for 3NT would be 62+ HCP combined and 6NT would require 83+ HCP and 7NT 94+ HCP
A 15 to 17 notrump would be 37-42 HCP.
A 12-14 notrump would be 30-35 HCP

I am sure this is an improvement over current point count, but I am not sure by how much.

Rainer Herrmann
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#35 User is offline   Zelandakh 

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Posted 2016-July-20, 06:43

View Postrhm, on 2016-July-20, 05:36, said:

A=11
K=7
Q=4
J=2
T=1

Exactly, another good option that illustrates the greater flexibility of working off of a point count rather than trying to force things into a basis of 13 (tricks).
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#36 User is offline   mycroft 

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Posted 2016-July-21, 09:10

Liversidge, if you don't want to go down after 1NT AP, play a strong NT. Part of the benefit of 12-14 is the preemptive value of the bid, and that means you are going down sometimes (you're going down more than rarely with 15-17, too, by the way). I would want to see the scores and see why your down was a bad score - it is likely that partner had enough that if they come in, it's going down too, or you went -2 vul for 200. If the latter, oh well, it happens. Why didn't everyone else do it (as I know you're in Acol-land, so you should have a lot of company. Maybe everyone in your club plays variable?) If the former, then your opponents judged well or got lucky when they passed it out. They'll judge badly next time. The arguments are different in my world (where we're the only ones playing 12-14 in the entire room).

But the other reason you open 12-14 with three aces and spaces is that if you don't, you'll never catch up when partner opens. Occasionally (unless it's me, of course) your partner actually has something, and will never play you for 3 aces as a passed hand.
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#37 User is offline   Th0rss0n 

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Posted 2018-August-15, 16:11

Going back to the point count, are not the K, Q, J & T all worth more when accompanied?
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#38 User is offline   dokoko 

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Posted 2018-August-19, 07:56

View PostCyberyeti, on 2016-July-17, 12:30, said:

There is another consideration, what will everybody else do ? Very few people will pass a flat 12 count these days, certainly not more, so you're going against the field if you do.


This sounds as if you shouldn't go against the field freely. But this is only true if

- the field's choice is superior or
- you have a definite edge in the play of the hand (this includes defensive play) or
- you prefer average minus to a 50-50 top-or-bottom shot.

Otherwise go against the field if it seems right.
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#39 User is offline   pescetom 

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Posted 2018-August-19, 11:07

View Postrhm, on 2016-July-20, 05:36, said:

A=11
K=7
Q=4
J=2
T=1

That reflects the values cited here very precisely, errors of 0% 1% 3% 10% 4% respectively.

Compare to A=4 K=3 Q=2 J=1 T=0 which has errors of 0% 14% 25% 40% infinite% respectively.

But a good compromise might be to use A=3 K=2 Q=1 J=2/3 T=1/3 which has errors of 0% 3% 12% 10% 22% respectively.
That gives 7 points per suit which is easier to calculate mentally than 25 and still a lot more precise than 10. If counting the J and T in thirds is too much of a pain then probably someone can come up with a rule of thumb that assigns half-point range scores to various JT holdings.
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#40 User is offline   rmnka447 

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Posted 2018-August-20, 10:01

View PostTh0rss0n, on 2018-August-15, 16:11, said:

Going back to the point count, are not the K, Q, J & T all worth more when accompanied?


Yes, they are, but how much more is a question for debate. Most of the really good players I know start from the basic point count and then use adjectives to characterize the hand -- "poor'. "bad", "nondescript', "decent", "good", "great", etc. They reflect the evaluation of the hand that goes past the point count and reflect the mental evaluation of plus and minus factors that affect hand value. These include positives such as honors working together, intermediates, intermediates working with honors, extra QTs, honors in long suits, or, negatives such as isolated honors (especially dangling Qs or Js), unguarded honors, weak long suits, lack of intermediates, intermediates not working with honors, lack of QTs.

Most often hands will have a combination of plus and minus factors that offset and the rating will be toward the middle of the scale of descriptions. Those hands will be bid normally. But sometimes hands will have lots of positive factors or negative factors that will predominate and the rating will be toward the top or bottom end of the scale. When they are toward the negative and near the bottom point count for an initial bid, the hands will be bid more pessimistically -- don't accept invitations -- or, in the extreme, choose a weaker initial bid. OTOH, when positive and near the top point count for an initial bid, the hands will be bid more aggressively -- invitations accepted, or, in the extreme, choose a stronger initial bid.

Maybe a few examples would help --

Consider AQx xx AQxx xxxx. You have 3 QT 12 HCP hand. The positives are the honors are working together and 3 QTs are more than usual for a 12 point hand. The negatives are no intermediates and one of the long suits is honorless. On balance, this is a good 12 point hand. If you're playing weak NTs (12-14), you ought to have little trouble opening 1 NT.

How about QJ AJx Qxxx Qxxx? This is 1 QT 12 point hand. But it has lots of negatives -- unguarded QJ, Q empty 4th in both long suits, no intermediates. This is a bad 12. If playing weak NTs (12-14), this is a hand you would likely pass rather than open 1 NT.

How about 1098 109 AQ109 AQ109? This is again a 3 QT 12 point hand, but it has about as many positives you can get -- honors working in combination, lots of intermediates, and intermediates working with honors in the long suits. So it's a great 12.

Make it a little better K109 109 AJ109 KQ109 -- 13 point 3 QT hand and you'd have little problem accepting any 2 NT invitation bid by partner.

Make it a little better A109 109 AJ109 KQ109 -- 14 point 3 QT hand and you might even consider treating it like a 15-17 hand.
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