Can anybody calculate this?

[bid_em_up]

What would be the expected frequency (1 every X # of deals) of a making small slam by either side? Grand slam?

 

Use whatever constraints you wish, I'm not looking for an exact calculation, just a reasonable approximation of how often you can/should expect a slammish hand to occur.

 

I'm not really concerned about the freak 18 hcp slams or 21 hcp ones necessarily, just normal 30+ hcp ones or 26 hcps that include a stiff or void opposite no wasted values.

[ArcLight]

I think in one of Ron Klingers books he says a slam occurs on around 10% of deals.

 

A part score on 50% of deals.

Games on 40% of deals.

 

 

 

( I have edited this post to replace "hand" with "deal" in case my meaning was not clear)

[kenrexford]

I think in one of Ron Klingers books he says a slam occurs around 10% of hands.

A part score on 50%, and a game on 40%

That would mean that 20% of game+ deals would also be slam deals, an interesting fact. Also, about 44% of deals with no slam are game hands.

 

I'm not sure what to do with that information.

[jdonn]

I think in one of Ron Klingers books he says a slam occurs around 10% of hands.

A part score on 50%, and a game on 40%

That would mean that 20% of game+ deals would also be slam deals, an interesting fact. Also, about 44% of deals with no slam are game hands.

 

I'm not sure what to do with that information.

Write a sequel?

[SoTired]

50% for part score seems right. 10% for slam seems about right since about 1 or 2 slams per session (26 boards) are bid

[kenrexford]

Write a sequel?

I'm thinking more of a prequel, directed by Peter Jackson.

[kenrexford]

50% for part score seems right. 10% for slam seems about right since about 1 or 2 slams per session (26 boards) are bid

But, you won't commit to the game percentage? Talk about hedging.

[han]

I suspect that by "hands", Klinger meant "deals", though I could be wrong. So I expect that on 10% of all deals at least one side has a slam, and on 50% of all hand no side has a game.

[BebopKid]

Hating to get into another probability debate, I thought I remember somewhere the odds being

 

2.5%-5% should be passout

2.5%-5% should be slam

35%-40% should be game

The rest partscore.

 

I have no idea where I heard this and it may be wrong

[kenrexford]

Hating to get into another probability debate, I thought I remember somewhere the odds being

 

2.5%-5% should be passout

2.5%-5% should be slam

35%-40% should be game

The rest partscore.

 

I have no idea where I heard this and it may be wrong

There is no way that a slam is just as likely as a pass-out.

[matmat]

i think a slam can be made on nearly any hand, if the defence cooperates fully.

[BebopKid]

There is no way that a slam is just as likely as a pass-out.

I found this on the Internet at Bridge Hands, does this sound right?

Probability that either partnership will have enough to bid game, assuming a 26+ point game = 25.29% (1 in 3.95 deals)

 

Probability that either partnership will have enough to bid slam, assuming a 33+ point slam = .70% (1 in 143.5 deals)

 

Probability that either partnership will have enough to bid grandslam, assuming a 37+ point grandslam = .02% (about 1 in 5,848 deals)

 

I havenot had time to write my own validation program yet, but I will.

[kenrexford]

There is no way that a slam is just as likely as a pass-out.

I found this on the Internet at Bridge Hands, does this sound right?

Probability that either partnership will have enough to bid game, assuming a 26+ point game = 25.29% (1 in 3.95 deals)

 

Probability that either partnership will have enough to bid slam, assuming a 33+ point slam = .70% (1 in 143.5 deals)

 

Probability that either partnership will have enough to bid grandslam, assuming a 37+ point grandslam = .02% (about 1 in 5,848 deals)

 

I havenot had time to write my own validation program yet, but I will.

That may be true. The percentage of time that a slam with 33+ HCP's occurs may be as low as .70%. Who requires 33+ HCP's for slam, though?

 

This would be an incredibly interesting fact, if both numbers are accurate.

 

Slam makes on 10% of the deals.

Slam with 33+ HCP's occurs on 0.70% of the deals.

Hence, 93% of hands where slam makes have less than 33+ HCP's.

 

That seems like quite an indictment of HCP analysis for slams, eh?

[jdonn]

There is no way that a slam is just as likely as a pass-out.

I found this on the Internet at Bridge Hands, does this sound right?

Probability that either partnership will have enough to bid game, assuming a 26+ point game = 25.29% (1 in 3.95 deals)

 

Probability that either partnership will have enough to bid slam, assuming a 33+ point slam = .70% (1 in 143.5 deals)

 

Probability that either partnership will have enough to bid grandslam, assuming a 37+ point grandslam = .02% (about 1 in 5,848 deals)

 

I havenot had time to write my own validation program yet, but I will.

That may be true. The percentage of time that a slam with 33+ HCP's occurs may be as low as .70%. Who requires 33+ HCP's for slam, though?

 

This would be an incredibly interesting fact, if both numbers are accurate.

 

Slam makes on 10% of the deals.

Slam with 33+ HCP's occurs on 0.70% of the deals.

Hence, 93% of hands where slam makes have less than 33+ HCP's.

 

That seems like quite an indictment of HCP analysis for slams, eh?

True that, though in fairness how many of the slams with under 33 points were in notrump with two balanced hands? Since that's the only time people really use high card points to evaluate.

[helene_t]

The first 10000 deals from the gib dd database:

293 grand slams

1306 small slams

5739 games

The rest (2662 if I calculate correctly) are partscores. Not a single passout.

 

If the success of a contract depends on right-siding, I allowed the declaring party to rightside it.

[han]

Nice Helene!

[bid_em_up]

What originally got me started on this subject was the quote from Bridge Hands (although I couldn't find again when I started this post).

 

Probability that either partnership will have enough to bid slam, assuming a 33+ point slam = .70% (1 in 143.5 deals)

 

Now this would include both balanced hands and unbalanced as well, although admittedly, unbalanced certainly may require much less for slam purposes.

 

So why is that so frequently on BBO, you see two or three slams bid and made back to back? The ratio seems to be more in line with 1 every 5-6 hands, or is it just my perception of it?

[han]

So why is that so frequently on BBO, you see two or three slams bid and made back to back? The ratio seems to be more in line with 1 every 5-6 hands, or is it just my perception of it?

[skip]

[skip]

 

That may be true.  The percentage of time that a slam with 33+ HCP's occurs may be as low as .70%.  Who requires 33+ HCP's for slam, though?

 

This would be an incredibly interesting fact, if both numbers are accurate.

 

Slam makes on 10% of the deals.

Slam with 33+ HCP's occurs on 0.70% of the deals.

Hence, 93% of hands where slam makes have less than 33+ HCP's.

 

That seems like quite an indictment of HCP analysis for slams, eh?

[kenrexford]

The first 10000 deals from the gib dd database:

293 grand slams

1306 small slams

5739 games

The rest (2662 if I calculate correctly) are partscores. Not a single passout.

 

If the success of a contract depends on right-siding, I allowed the declaring party to rightside it.

Great numbers!

 

Roughly 16% of deals are slam deals.

Roughly 57% of deals are game deals.

The rest (roughly 27%) are partscore deals.

 

Of slam deals, roughly 18% are grand-slam deals.

Of deals where game+ is there, roughly 21% are slam deals.

 

This last statistic is interesting. One in five game deals actually are slam deals, and one in five slam deals are actually grand slam deals.

 

The bridge hands numbers are WAY off, or extremely telling.

 

This number suggests that 33 HCP slams are roughly 4.3% of the slams that you need to worry about. 95.7% of slams apparently require less than 33 HCP's.

[awm]

It's worth considering though, that the double-dummy numbers may be a bit high. A number of games and slams will be higher percentage on double-dummy play. For example, consider a slam on a two-way guess of a queen -- it's only 50% (a bit better if you can get count) whereas double-dummy it's 100% cold.

 

While it's true that the double-dummy nature of the analysis can help the defense too, I suspect that on slam deals (where the defenders will rarely have the lead) double-dummy creates an artificial declarer advantage.

 

It could also be that there are a lot of deals where slam is possible but anti-percentage. Say we have 100 hands, and on 50 of them slam is (looking at my hand and partner's) 20% whereas on the other 50 slam has no play. The reality is that partner and I won't want to bid any slams on these 100 hands, but double-dummy analysis will probably say there are "10 slam deals" in the set.

[jtfanclub]

How about actual results?

 

Out of the last N hands actually played on BBO, how many made 12 tricks? How many 13?

[awm]

I guess my (anecdotal) experience is that there are a fair number of boards where I don't bid slam and slam is lousy looking at my hand and partner's, but things lie very favorably and slam ends up making. It feels like there are probably more of these than hands where slam is actually good in fact! But these are basically "unbiddable" slams because if you bid them you will also end up bidding a much larger number of slams which are equally lousy and where the cards don't like favorably...

 

For example, there are a lot of hands where there are three finesses (or two finesses and a suit break, etc) where if everything works you make six, if nothing works you fail in four. Obviously you want to be in game on these hands and not slam, but the double dummy analysis will say that 1/8 of these are slam hands, 3/4 game hands, and 1/8 partscore hands.

[helene_t]

It's worth considering though, that the double-dummy numbers may be a bit high. A number of games and slams will be higher percentage on double-dummy play. For example, consider a slam on a two-way guess of a queen -- it's only 50% (a bit better if you can get count) whereas double-dummy it's 100% cold.

 

While it's true that the double-dummy nature of the analysis can help the defense too, I suspect that on slam deals (where the defenders will rarely have the lead) double-dummy creates an artificial declarer advantage.

I think we have had this discussion of bias in DD results. AFAIR the conclusion was a slight bias in favor of defenders due to the lead, but you may be right that that is less of a concern for slam deals. Not sure though. For my feeling, many slams (especially small slams) turn out to be settable with a specific lead that is hard to find. Maybe this is an artificat of slams being more post-mortemed than non-slams.

 

But generally I agree with you. Sometimes you have a double fit and only one of the two denominations makes game, sometimes game needs to be rightsided, sometimes 3NT is the only game with a 8- or 9-card major fit etc. All this makes for a lot of DD games that would never be bid in practice.

[Gerben42]

Not a single passout

 

Par 0 deals are quite rare, Thomas Andrews has some on his site.

[Mr. Dodgy]

How about actual results?

 

Out of the last N hands actually played on  BBO, how many made 12 tricks?  How many 13?

I have just over 13000 of the hands I have played on BBO recorded:

 

By declarer:

 

13 tricks: 310 times (~2%)

12 tricks: 951 times (~7%)

11 tricks: 1940 times (~15%)

10 tricks: 2632 times (~20%)

9 tricks: 2746 times (~21%)

8 tricks: 2084 times (~16%)

7 tricks: 1337 times (~10%)

6 tricks: 612 times (~5%)

5 tricks: 262 times (~2%)

4 tricks: 104 times (~1%)

3 tricks: 22 times

2 tricks: 4 times

1 trick: 0 times

0 tricks: 2 times

 

passed out: 125 times (~1%)