[mycroft]

I'm surprised that with [20]21-23 high, everyone's so optimistic that they're going to get to play 2♠, and they're not going to be playing 3 on the best opening lead.

It would be fun to find out, on those sim hands, what par is, and how often it's -100 for -1x (which in real life will frequently be -50, and even if 4♠ is -2 for -100, double isn't automatic, especially if you get there immediately.)

I was thinking of bidding Texas, because it might make, but it also might beat 3♥ after the lower transfer gets doubled, or 3♣ when fourth hand with AKTxxx, a stiff spade and a 12 count comes in.

I may do that more often than I should because I spend so much of my time playing weak NT (where I think this is automatic Texas, but as a preempt). I would certainly think I was right if the round suits were reversed.

[MrAce]

I am totally with you on not overbidding, in fact I prefer under bidding in most of the doubtful decisions at MP and playing in a field that you think you are better than the average of the field.

[gszes]

At IMPS I would invite but I see little advantage to upping the level at MP to reach for what is probably still a sketchy game. This is the type of hand that helps one find a compatible partner.

[nige1]

AntonyLee 'Matchpoints. Partner will occasionally upgrade 14 counts, but not very aggressively.
You have the option of showing a 5(!)-card invite (which can be balanced or not) by bidding Stayman then 2♠ (over which partner's 2N would be a shortness ask).

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rhm, on 2019-December-14, 04:26, said:

This is easy to simulate. I used 1000 random deals giving North a balanced 15-17 HCP. If North declares double dummy North makes

• 10 tricks or more on 495 deals (49.5%)
• 9 tricks on 820 deals (82%)
• 8 tricks on 972 deals (97.2%)

Simply transfer and raise 2♠ to 3♠, assuming you can not show shortage in an invitational hand.

smerriman, on 2019-December-14, 13:45, said:

Rainer's numbers surprised me, so I ran my own 1000 hands to compare. I got slightly different figures for North declaring in spades (and the opposite conclusion):

• 10 or more tricks on 46.9% of hands
• 9 or more tricks on 84.2% of hands
• 8 or more tricks on 96.7% of hands

Under the assumptions that:

• North will accept an invite with any 16+ HCP
• North will superaccept with 17 HCP and 4 spades:

and comparing transferring and passing with transferring and inviting:

• 2.5% of the time, opener superaccepts (excluded from cases below)
• 15.8% of the time, we take 8 or less tricks, so passing wins
• 19.2% of the time, we take 9 tricks, but opener accepts an invite, so passing wins
• 17.2% of the time, we take 9 tricks, but opener rejects the invite so it doesn't matter
• 15.8% of the time, we take at least 10 tricks but opener rejects an invite, so it doesn't matter
• 29.5% of the time, we take at least 10 tricks and opener accepts an invite, so inviting wins

This means passing the transfer is better than inviting with 3♠ - it wins 35% of the time, and loses 29.5% of the time.
(This sim doesn't take into account upgrades - ie allows North to have 17 counts with a good 5 card suit and no 14 counts - but of course, adjusting for that makes North weaker, so would be more in favor of staying low.)

Thank you, rhm and SMerriman for the educational simulations.

• Without the simulations, I would transfer -- and bid game only after a super-accept. Many top BBO players deride the LTC (Losing Trick Count) and its variations. Almost all experts seem to believe it's inapplicable in notrump auctions. Nevertheless, some ordinary players rely on such crude tools to aid judgement, I confess that my favorite WTC (Winning Trick Count) undervalues the OP hand as 3.5 winners (SA = 1.5. ♣ singleton = 2). If the 1N opener has ♠ support, then you can add 1 trick for trump control. Arguably, in context, ♠JT are also worth almost a trick but that you might regard that as special pleading
• Now, rhm's advice seems apt -- transfer and invite.
• AntonyLee's suggestion is also attractive: 2♣ (Stayman), then 2♠ (Invite), allowing opener to try for game with a shortage-ask.

But it's a close decision, For example, AntonyLee makes an excellent point about picking up ♠Q at double-dummy.