We all play club pairs type games and we always see daft 3NT contracts on the traveller when we play in 4/
(just because we have an 8 or 9 card fit). Maybe some simulations on the matchpoint benefits/ lack thereof of random 3NT punts would be good. Or just some definitive answer as to how much the computer says they should be losing by...
It's a bit hard to define what a "random 3NT punt" is, so I'm going to reword the question like this:
Partner opens 1NT and we have any balanced hand worth 3NT, regardless of major length. Of the hands where we have an 8-card major fit, how much better is it to play there than to play in 3NT?
In fact, I'm just going to restrict it to hands where we have a heart fit as it makes no difference. The criteria are as follows:
- Partner is 12-14 balanced
- RHO has 0-14 points and 7 losers or worse
- We have 12-18 balanced
- We have 8+ hearts between us
Over 25,000 tests, we see the following:
Tricks 3NT 4
0 0 0
1 0 0
2 1 0
3 4 0
4 12 0
5 94 1
6 490 20
7 1893 160
8 4785 1129
9 6660 4898
10 5555 9249
11 3780 7075
12 1528 2195
13 198 273
So, on that evidence, it seems that just punting 3NT has a lot going for it. It's a loser, but not by very much so if you fancy a swing then it might be worth a shot. Incidentally, at IMPs scoring you lose 1.02 IMPs/board by bidding 3NT, so it's really not a good idea.
NT is best: 10280
Hearts is best: 12619
Both the same: 2101
Some experienced players will be shifting around in their seats now, crying that this is rubbish analysis. Yep, it is. The criteria are too general. We know from playing lots of bridge that if you have thin game values, you'd rather be in the major but if you have plenty of extras then the need to ruff losers isn't so great and 3NT will often make the same number of tricks. Also, we know that with a 4333 hand we will usually just bid 3NT over 1NT regardless of whether we have a major or not as it's likely to play the same. So let's break it down.
Using test runs of 1000:
Your point count
12-13 14-15 16-18
NT is best: 345 454 623
Hearts is best: 522 500 371
Both the same: 133 46 6
NT IMPs: -1.23 -0.96 -0.66
Combined Hearts
8 9 10
NT is best: 421 354 236
Hearts is best: 483 591 689
Both the same: 96 55 75
NT IMPs: -0.81* -2.16 -2.76
Your hand shape
3433 2533 4432
NT is best: 467 458 324
Hearts is best: 393 473 561
Both the same: 140 69 115
NT IMPs: +0.59 -1.07 -1.64
Now, I should probably break it down even further and find out what point ranges are best for 3NT in a 5-3 fit etc. etc. but that's going a bit over the top, I think. Generally speaking: 4333 shapes indicate 3NT; stronger point counts indicate 3NT; 5-3 fits indicate 3NT. Combining these factors will just do what you expect it to do.
Type of fit
4-4 5-3
NT is best: 339 516
Hearts is best: 549 401
Both the same: 112 83
NT IMPs: -0.75* -0.23*
Note that punting 3NT is never a really stupid thing to do at pairs. Even if you have a 5-5 heart fit that you're missing, you'll still get a good result about a quarter of the time! Note also that playing in 3NT is almost always a substantial loser at IMPs, the only exception being when you're 4333. So punting 3NT and eschewing your major is purely a pairs manoeuvre.
This is just a brief skimming of this area as the subject of 3NT simulations seems to have been done to death on rec.games.bridge. Try this thread for starters.
So to answer Phil's question, those bastards who punt 3NT and get a good result against you are indeed being lucky, but not as lucky as you might have first thought.
* Edit: see comments for slightly more accurate results.
6 comments:
I’m not sure I’m understanding your tables here: in the “your point count” 16-18 HCP, NT is best 623 vs. 371, yet the NT scores –ve imps. Is the suggestion that it would gain at MP (better more often) but loose at IMPs none-the-less?
There is a similar sort of set of numbers in the type of fit table: does this suggest that at MPs you should consider playing 3NT rather then 4H with a known 5-3 fit (if you know that partner is 5332 exactly…)? If that really is the case then conventional wisdom should be set on it’s head somewhat.
Ta for the great work though.
PSS
The first one of those makes sense, at least. When partner is 12-14 and you are 16-18, most likely both contracts are making. At MP, you gain when NT takes the same number of tricks, but lose when the major takes an extra trick. At IMPs you still lose an IMP when the major takes an extra trick, but no longer gain because +10 is a push.
Something that puzzles me:
If you have an 8-card fit it is either 4-4 or 5-3 (because both hands are balanced). If 4-4 we lose 0.75 IMP per board; if 5-3, 0.23. So the average for 8-card fits should be between these, which it isn't.
Phil - yes, you gain at MP but lose at IMPs. That's because the gains are frequent but small (often just 10 points) while the losses are generally larger. You'll lose a lot more game swings by playing in 3NT. I just ran another 1000 and we lost 57 big swings while gaining only 21. Add to that the frequent 1 IMP losses and you can see why it's still a loser at teams.
As far as 5-3 fits are concerned, are these findings so controversial? You often won't have any need/chance to ruff anything in the suit contract, so you may as well play in 3NT. It's more dangerous, because you run the risk of losing control but at pairs you'll pick up plenty of tiny swings in. I suppose DD will be slightly biased as the defence will know precisely when they have to lead trumps — in real life, you may well be able to ruff something in the short hand — but I doubt if it changes much.
For the apparent contradiction in the results, that's a good spot! It seems I was being very lazy with my sample sizes. 1000 tests isn't at all enough for me to go around quoting figures to two decimal places. The tests run pretty slowly if you have a lot of them (we're doing two DD analyses for each test, remember) and I couldn't be bothered to wait that long!
Note that the relatively small number of game swings have a large effect on the overall IMP figures. An error of just 10 game swings in one direction will change the final figure by about 0.12 IMPs. So take those IMPs figures with a pinch of salt; there's probably at least a 0.2 IMP error.
Over 10,000 tests the overall figures for an 8 card fit come out at -0.73 and I think that's going to be a lot more reliable.
2,000 tests for 4-4 fits came out to -0.96 and 2,000 tests for 5-3 fits came out to -0.34. This at least looks more accurate. Whether it is or not, I'd probably need to do 100,000 tests over a weekend.
A few comments -
I think punting 3NT will tend to work better in real life than these figures suggest. This is because you are giving less info to the oppo - you will sometimes gain on hands where you don't have a fit because you didn't look for one. I'm not quite sure how to estimate the importance of this.
With regard to 5-3 fits, I'm not sure how useful this data is - bear in mind that
1NT:2D, 2H:3NT
is often played as showing a 5332, so will normally be passed by a 4333 with three-card support.
How about comparing strategies for a 5332 responder - Bidding 3NT, Bidding Stayman, Transferring then bidding 3NT. The last category could be split up with regard to opener's strategy - Should a 4333 with *four*-card support correct to 4M or not?
BTW, am finding this all fascinating...Hopefully at some point I will get around to doing sims myself!
Of course, point count will still have a big affect - might be worth running for 12 points and for 15, say. Or you could take it another step further and specify responder's hand, changing it to look at the impact of suit quality/holdings in your doubleton, etc - starting to sound quite time consuming now though!
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