[gnasher]

awm, on Aug 3 2010, 05:18 AM, said:

Recently I've gotten some bad results from this, although part of it has been partners opening 1NT on hands where I wouldn't (recently Kx AKx KQJxxx xx for example) so perhaps this is not wholly my fault.

If those are the only games you're missing, it's not at all your fault. If you're treating that hand as balanced, it's worth at least 18.

[JLOGIC]

gnasher, on Aug 3 2010, 12:26 PM, said:

awm, on Aug 3 2010, 05:18 AM, said:

Recently I've gotten some bad results from this, although part of it has been partners opening 1NT on hands where I wouldn't (recently Kx AKx KQJxxx xx for example) so perhaps this is not wholly my fault.

If those are the only games you're missing, it's not at all your fault. If you're treating that hand as balanced, it's worth at least 18.

I don't understand treating it as balanced anyways, it's perfect for 1D then 3D. It is tough to evaluate it as a balanced hand since it's just a good hand with 6 good diamonds and a lot of playing strength...

[MartenW]

bluecalm, on Jul 31 2010, 05:04 PM, said:

Ok, so for example holding this hand:

Dealer: ????? Vul: ???? Scoring: Unknown

♠ QT5 ♥ T4 ♦ KJ3 ♣ QT953

facing 1NT 15-17 (5card major possible) we have the following results:

Opposite exactly 15count available tricks (1000 simulated hands):

tricks:
<7 7 8 9 10 11 12 13
128 208 340 246 70 8 0 0

1nt makes: 872 times
2nt makes : 664 times
3nt makes: 324 times

opposite 16-17 count:

<7 7 8 9 10 11 12 13
61 121 245 315 206 51 0 0

1nt makes: 938 times
2nt makes: 817 times
3nt makes: 572 times

Let's compare passing and inviting at IMPs non vulnerable:

a)if we face 15 count
on 128 hands passing gains 2 imps (undertricks)
on 208 hands passing gains 4imps (90 + 50)
rest of the hands it doesn't matter.

Overall: 1088 imps or 1.08 imp/board

b)if we face 16-17count
on 61 hands passing wins 3 imps (-50 opposite - 150)
on 121 hands pasing gains 5imps (90 + 100)
on 245 hands passing gains 5imps (120+50)
on 572 hands passing loses 6imps (game versus partscore)

Overall: 1419imps or 1.419 imp/board

Now we have to determine how often we face exactly 15count and how often we face 16-17. According to my simulator it's: 57.4% for 16-17 and 42.6% for exactly 15.

So overall inviting gains 0.35imp/board.

Of course at matchpoints the result will be much more convincing.

Very interesting topic.

Since this post did not consider comparisons between all three available strategies (pass, invite, bash) I decided to calculate these strategies with the given data.

Assumptions:

The hand is as given and partner opens 1NT. Three situations are covered: matchpoints, IMPS nonvul and IMPS vul. In each situation 1/3 of the field passes, 1/3 of the fields invites with all 16-17 hands accepting and all 15 hands passing and 1/3 of the field bashes (bids 3NT).

Results:

All results are averages over all outcomes.

Matchpoints:
- Pass: 53.1%
- Invite: 52.2%
- Bash: 44.6%

NV IMPS:
- Pass: -0.51
- Invite: +0.23
- Bash: +0.28

VUL IMPS:
- Pass: -1
- Invite: +0.39
- Bash: +0.61

These results seem to suggest that indeed passing or bashing seems to be a good strategy. Inviting seems to be never the best, however if you have to stick with one strategy for both MP and IMPS then inviting is best. I'm not sure how valuable this is, considering all play is double-dummy; but inviting is clearly worse off if the play is not double dummy, since defending becomes easier. However the possibility of finding a major suit fit when is not taken into account, which sometimes makes inviting more attractive.

PS: NV IMPS the whole field actually loses -0.10 imp on average, this is because of the sublinear IMP curve, for example if you get +100 and two others -50, you get 3 imps while they both get -2, and imps are lost. I added +0.10 to these scores to make the average 0. Funny, I never realized that playing IMP pairs you lose imps on average.

[gwnn]

welcome to the forums!!