[Stefan_O]

tnevolin, on 2016-August-13, 12:44, said:

I finally downloaded them! Thanks for interesting source. The sad thing is that there is only 10k boards there. A tiny amount.
Anybody knows some similar sources?

How much of the site did you download?

There are several different types of competitions,
and it looks like all(?) 2015 and some of the 2014 events have full hand-records...

http://www.eurobridg...ory/index2.html
(click: Competitions => Championships => ... in the left-margin)

[Stefan_O]

tnevolin, on 2016-August-13, 12:44, said:

I finally downloaded them! Thanks for interesting source. The sad thing is that there is only 10k boards there. A tiny amount.
Anybody knows some similar sources?

Here some other sources:

http://www.angelfire...pbnarchive/pbn/

http://home.claranet...n_databases.htm

[tnevolin]

Stefan_O, on 2016-August-13, 15:14, said:

How much of the site did you download?

There are several different types of competitions,
and it looks like all(?) 2015 and some of the 2014 events have full hand-records...

http://www.eurobridg...ory/index2.html
(click: Competitions => Championships => ... in the left-margin)

I scanned all the events, rounds, tables and Boards there are. Apparently they just started recording boards since 11. That's all they have.

[jogs]

Stefan_O, on 2016-August-13, 06:11, said:

Yes... the datafile indeed does indicate the opposite...
i.e. with a given combined HCP-strength [22-25],
you are more likely to score 9+tricks if you bid 3NT, than in if you do not.
Outcome:

When both hands are 4333/4432/5332 and the pair ends up in an NT-contract:
- if they have 25 HCP and the contract is 1NT, they score at least 9 tricks in 57.20% of the cases (6913 samples)
- if they have 25 HCP and the contract is 2NT, they score at least 9 tricks in 55.48% of the cases (5056 samples)
- if they have 25 HCP and the contract is 3NT, they score at least 9 tricks in 62.28% of the cases (61179 samples)
- if they have 25 HCP and the contract is 4+NT, they score at least 9 tricks in 56.75% of the cases (289 samples)

- if they have 24 HCP and the contract is 1NT, they score at least 9 tricks in 42.87% of the cases (16882 samples)
- if they have 24 HCP and the contract is 2NT, they score at least 9 tricks in 43.10% of the cases (12421 samples)
- if they have 24 HCP and the contract is 3NT, they score at least 9 tricks in 49.31% of the cases (47500 samples)
- if they have 24 HCP and the contract is 4+NT, they score at least 9 tricks in 46.95% of the cases (164 samples)

- if they have 23 HCP and the contract is 1NT, they score at least 9 tricks in 29.67% of the cases (29047 samples)
- if they have 23 HCP and the contract is 2NT, they score at least 9 tricks in 30.60% of the cases (15530 samples)
- if they have 23 HCP and the contract is 3NT, they score at least 9 tricks in 36.44% of the cases (25448 samples)
- if they have 23 HCP and the contract is 4+NT, they score at least 9 tricks in 29.17% of the cases (96 samples)

- if they have 22 HCP and the contract is 1NT, they score at least 9 tricks in 18.35% of the cases (35317 samples)
- if they have 22 HCP and the contract is 2NT, they score at least 9 tricks in 21.02% of the cases (10307 samples)
- if they have 22 HCP and the contract is 3NT, they score at least 9 tricks in 24.61% of the cases (10829 samples)
- if they have 22 HCP and the contract is 4+NT, they score at least 9 tricks in 18.52% of the cases (54 samples)

(4+NT means 4NT or higher NT-contract)

Not very surprising, really, since overall, declarer has a much better picture of the deal and his risks/chances and knows what he is doing, than defenders.

I'm surprised by the results. Collectively we don't defend very well. I found this board in ACBL BBO online mini.

---

The contract is 3NT

T1: ♠3, ♠5, ♠q

1/3 of declarers allowed the ♠q to win. Every East played a spade at trick 2.
What's wrong with the ♦K?

West had QJxx in diamonds.

[jogs]

jogs, on 2016-August-15, 17:44, said:

I'm surprised by the results. Collectively we don't defend very well. I found this board in ACBL BBO online mini.

---

The contract is 3NT

T1: ♠3, ♠5, ♠Q

1/3 of declarers allowed the ♠Q to win. Every East played a spade at trick 2.
What's wrong with the ♦K?

West had QJxx in diamonds.

[Stefan_O]

jogs, on 2016-August-15, 17:44, said:

I'm surprised by the results. Collectively we don't defend very well.

Yes, I guess your second statement accounts for the first

[Stefan_O]

jogs, on 2016-August-15, 17:44, said:

I'm surprised by the results. Collectively we don't defend very well. I found this board in ACBL BBO online mini.

---

The contract is 3NT

T1: ♠3, ♠5, ♠q

1/3 of declarers allowed the ♠q to win. Every East played a spade at trick 2.
What's wrong with the ♦K?

Since you ask -- -- it looks like ♦K will block the suit, if West has ♦QJx.
But that could perhaps be ruled out from the auction?

[Stefan_O]

jogs, on 2016-August-15, 17:44, said:

Collectively we don't defend very well.

And yes, after 30+years of this game, I will confess I still do far more mistakes in defense than as declarer -- esp. those that look really stupid when you see the full hand

[jogs]

IMP pairs, dealer North

EW silent

The two most common auctions were

1C - 3NT all pass

1C - 2NT, 3NT all pass

South had 9 tricks off the top.

[Stefan_O]

jogs, on 2016-August-16, 10:15, said:

South had 9 tricks off the top.

And so many ducked the ♠ lead with nothing in ♦?
Are you sure it was IMPs?

I guess, collectively, we are not so good at declaring neither then?

[jogs]

Stefan_O, on 2016-August-16, 11:03, said:

And so many ducked the ♠ lead with nothing in ♦?
Are you sure it was IMPs?

I guess, collectively, we are not so good at declaring neither then?

Yes IMP pairs, ACBL BBO online. Players are beginners to AX in ability.
1/3 of the declarers ducked the opening lead.

[Zelandakh]

Is it really bad defence to make a plan based on declarer being logical and barely competent? Without an auction it is impossible to critique East's play but it is easy to know that declarer was not playing optimally. Finally, it seems wrong to me to take a competition aimed at beginners and then hold it up to criticism. Surely we should be looking at expert level competition for our hand database.

[jogs]

Doubt that very many of the players are beginners. Was just giving the entire range of abilities. There may even be some world class players in the field. Garozzo played in minis on OkBridge.

[jogs]

Stefan_O, on 2016-August-12, 14:29, said:

I ran another crunch on the same ~400K deals, to examine this relation.
Outcome:

When a pair has a combined 24 HCP and both hands are 4333/4432/5332, and they bid 3NT:
- if they have 24 HCP (12 vs 12), they make the contract in 50.10% of the cases (6271 samples)
- if they have 24 HCP (13 vs 11), they make the contract in 49.44% of the cases (9975 samples)
- if they have 24 HCP (14 vs 10), they make the contract in 51.25% of the cases (7005 samples)
- if they have 24 HCP (15 vs 9), they make the contract in 50.85% of the cases (8752 samples)
- if they have 24 HCP (16 vs 8), they make the contract in 48.11% of the cases (7151 samples)
- if they have 24 HCP (17 vs 7), they make the contract in 47.41% of the cases (3227 samples)
- if they have 24 HCP (18 vs 6), they make the contract in 47.19% of the cases (2115 samples)
- if they have 24 HCP (19 vs 5), they make the contract in 46.03% of the cases (1336 samples)
- if they have 24 HCP (20 vs 4), they make the contract in 44.39% of the cases (865 samples)
- if they have 24 HCP (21 vs 3), they make the contract in 41.47% of the cases (340 samples)
- if they have 24 HCP (22 vs 2), they make the contract in 47.32% of the cases (298 samples)
- if they have 24 HCP (23 vs 1), they make the contract in 28.57% of the cases (91 samples)
- if they have 24 HCP (24 vs 0), they make the contract in 47.30% of the cases (74 samples)

So, as long as the stronger hand has no more than 15 HCP, this data does not indicate any negative impact on your chances.

But stronger than that, it seems they start to fall off a bit...

5332 probably plays for more tricks than 4432 or 4333.
What does this look like if all 5332 patterns are removed from the sample space?
Does the percentage makes drop a significant amount?

TIA

[tnevolin]

Stefan_O, on 2016-August-13, 15:32, said:

Here some other sources:

http://www.angelfire...pbnarchive/pbn/

http://home.claranet...n_databases.htm

Parsed both pages for 2k records. Not too much. Some text on the second page says there are a lot of free PBN data in Gib or some other sites but I never found them in open access.
Anybody uses Gib? Is there a free PBN database there?

[tnevolin]

One good news and one bad news. I found a large game archive on BBO vugraph page. It is quite extensive: 400+k boards. Unfortunately, they all are manually entered and there are a lot of typos and mistakes. Some of them are easy detectable like impossible deal. Some of the are very hard to detect like one vugraph I found had N-S and E-W hands swapped. A very nasty error. When such error enter into analysis they pollute results. I am trying to devise empiric rules to filter such mistakes out. Anybody can propose such rule? I would prefer to filter out extra to make sure that rest of the observations are clean rather than leave incorrect entries. Thank you.

[Stefan_O]

tnevolin, on 2016-August-27, 13:37, said:

One good news and one bad news. I found a large game archive on BBO vugraph page. It is quite extensive: 400+k boards. Unfortunately, they all are hand entered and there are a lot of typos and mistakes. Some of them are easy detectable like impossible deal. Some of the are very hard to detect like one vugraph I found had N-S and E-W hands swapped. A very nasty error. When such error enter into analysis they pollute results. I am trying to devise empiric rules to filter such mistakes out. Anybody can propose such rule? I would prefer to filter out extra to make sure that rest of the observations are clean rather than leave incorrect entries. Thank you.

Hi Tim,

Hard to give some general rules, without probing the actual data/errors a bit, but
for your purposes, maybe it is OK to remove all "weird" results,
regardless of whether they were handtyping-mistakes or actually occurred at the table? (sh*t does happen )

If so, some rules I can think of...
Trump-contracts:
- if declaring side has a combined 6 or less trump-cards => SKIP THE DEAL
- if declaring side has a combined 7 trumps, and playing a major-contract higher than 4H/4S, or a minor-contract higher than 3C/3D => SKIP

NT-contracts:
- if the contract is 2NT or higher, and declaring side has 19 hcp or less => SKIP
- Perhaps, also require, for example, if the contract is 3NT, declaring side should have either 22+hcp or a 6+suit? => Ohterwise, SKIP
- and dito higher requirements for higher 4+NT contracts...

Any contract that goes down 4 or more, is probably not relevant to your analysis? => SKIP

Not sure if this is of any help to you?

But if not, maybe you can give some more detail what errors/issues you found, and any ideas you have,
and we might come up with better suggestions...

[tnevolin]

Stefan_O, on 2016-August-27, 19:38, said:

Hi Tim,

Hard to give some general rules, without probing the actual data/errors a bit, but
for your purposes, maybe it is OK to remove all "weird" results,
regardless of whether they were handtyping-mistakes or actually occurred at the table? (sh*t does happen )

If so, some rules I can think of...
Trump-contracts:
- if declaring side has a combined 6 or less trump-cards => SKIP THE DEAL
- if declaring side has a combined 7 trumps, and playing a major-contract higher than 4H/4S, or a minor-contract higher than 3C/3D => SKIP

NT-contracts:
- if the contract is 2NT or higher, and declaring side has 19 hcp or less => SKIP
- Perhaps, also require, for example, if the contract is 3NT, declaring side should have either 22+hcp or a 6+suit? => Ohterwise, SKIP
- and dito higher requirements for higher 4+NT contracts...

Any contract that goes down 4 or more, is probably not relevant to your analysis? => SKIP

Not sure if this is of any help to you?

But if not, maybe you can give some more detail what errors/issues you found, and any ideas you have,
and we might come up with better suggestions...

Good suggestions. I accualy tried something similar just more generic. Very roughly estimated number of tricks: for NT = HCP/3 + 1, for suit = HCP/3 + combined trumps/2 + 1. Then if result differs from estimated by 6 tricks I throw whole section away assuming that the same person entering the data could make other mistakes.
You can look at examples here: http://www.bridgebas...h_archives.php.
Most common errors are typos, missing results, missing hands, impossible hands (duplicate cards, missing cards).
The only one non typo error I found is swapped N-S, E-W hands. So the contract says something like 4HE but it was S who played it. Grrrr. I don't remember the exact vugraph but it is one on their page. You can even see the movie for it with this error right in plain sight.

[tnevolin]

Hi Everybody.
Sorry that I disappeared for a while. I was regrouping my calculation to optimize score improvement as well as trick prediction. Essensially I am trying to maximize the potential score (MPP and IMP) that my evaluation system would give to players. It is not finalized yet and I stumbled accross one formalization problem and I hope you can help me.
I am formalizing hand features for NT contract. Most of them are simple like high cards, long suit, high cards in long suit (the source of extra tricks). However, there is another important features affecting NT games outcome: stoppers. Usually it is the weakest and shortest suit that is the most dangerous for NT contract. Unfortunately, there are many factors and it is not easy to mathematically determine which suit is most beneficial for defenders. For example, you have short suit with very strong cards (AK) or long suit with very weak cards (T9876) - which one is to select as worst stopper? Another problem that stopper is a combined partnership effort. Partners surely can exchange each one best stoppers but it still unclear how to predict which suit will be defenders attack target because mere flag "stopper or no stopper" doesn't disclose information about partner's suit strength. What if partner showed stopper and you have another 3 low cards in it - does it make it significatly stronger? With partner's Kxx it doesn't, but with partner's Jxxx it gives only 6 cards to defenders lowering the risk of attack. And many more.
I would appreciate any suggestion on the topic. Try to think in formal terms (card face values, suit length, plus vague information about partner's declared stoppers) so that others can apply your rule without ambiguity. Thank you.

[Stefan_O]

Hi Tim,

I wish I had something intelligent to say here...

But without understanding a bit more about your framework, it seems unclear how to approach this.

Wondering... is it your idea, for example, that your method should actually subtract points from your combined strength,
when the final contract is NT and you also have a too weak holding in a suit,
so the adjusted point-count will reflect your actual trick-taking power in NT?

If so, holding AK seems worse than AQ (in declarers hand) since more points are wasted in a short suit rather than building tricks in long suits.

If you hold T9876 in a suit, however, it seems more likely that your weak spot (in 3NT) is not in this suit, but might be in a different suit?
So it seems the first issue for the players would be to figure out which suit is the weak one?

To take a simple example, let's say you hold:

AKJx xx Qxx AQxx

and the bidding goes

1NT-(P)-2NT-(P)
?

So here --- do you plan your system to subtract points, because you seem to have a weak spot in hearts?
That might be.

But on the other hand, pd might hold:

xxx AJT x Kxxxxx

so it's actually not hearts, but diamonds, that is your weak spot...

Would be interesting to hear some more, how you are designing or thinking around those methods.