Table Difficulty Factor (TDF) for measuring table "toughness"

dr_dave

Instructional Author
Gold Member
Silver Member
Calculate your Table Difficulty Factor (TDF) to determine how tough it plays relative to other tables. Only three pocket measurements are required, and you can use the TDF calculator or TDF spreadsheet to get your results.

username - table size, pocket mouth size, mouth-throat difference, shelf depth - TDF (table description)
Side Pocket - 10', 4 1/4", 1 1/4", 2 1/4" - 1.48 (1920s Brunswick)
CaptiveBred - 10', 4 1/8", >143.5deg, 1 1/2" - 1.43 (Brunswick Anniversary)
Bob Dixon - 9', 4", 145deg, 1 5/8" - 1.37 (Diamond Pro)
gregcantrall - 10', 4", 5/8", 1 1/2" - 1.31 (10' Diamond)
Ricky Sy - 9', 3 3/4", 1/4", 5/8" - 1.25 (money table)
TEAM SLO - 9', 3.85", 0.6", 1.5" - 1.24 (Diamond)
acedonkeyace - 9", 4", 1/2", 2" - 1.22 (gamble table)
ChrisinNC - 10', 4 1/4", 11/16", 1 5/16" - 1.22 (Gabriel Sentinel)
8cree - 9", 4.125", 0.813", 1.562" - 1.21 (Diamond)
Bonus Ball - 9', 3 7/8", 1/8", 3/4" - 1.19 (Bonus Ball table)
Marc Vidal - 9', 4 1/8", 13/16", 1" - 1.18 (Brunswick Tournament)
chevybob20 - 9', 4 1/8", 7/8", 1" - 1.18 (Centennial)
Baxter - 9', 4 1/4", 143deg, 1 1/8" - 1.18 (AMF Grand Prix)
Qaddiction - 9', 4 1/8", 3/4", 1 3/8" - 1.16 (Diamond)
angluse - 8'+, 3 13/16", 9/16", 7/8" - 1.16 (1935 Brunswick Challenger)
Tom Cruise - 9', 4", 1/8", 1 3/8" - 1.15 (Golden West)
ChrisinNC - 10', 4 3/8", 11/16", 1 5/16" - 1.15 (Gabriel Sentinel)
rexus31 - 9', 4", 3/8", 1" - 1.15 (1950s AMF)
FatBoy - 9', 4", 1/4", 1" - 1.14 (GC)
TATE - 9', 4", 1/4", 7/8" - 1.14 (GC)
Mikjary - 9', 4", 9/16", 1 5/16" - 1.13 (Brunswick Centurion)
ChrisinNC - 9', 4 1/8", 5/8", 1 1/4" - 1.13 (Gabriel Signature Pro)
rexus31 - 9', 4.125", 0.505", 1.125" - 1.12 (GC I)
Cardigan Kid - 10', 4.5", 0.88", 1.5" - 1.12 (GC)
Ralph Kramden - 9', 4 5/16", 1", 1 3/4" - 1.12 (GC I)
pocket - 9', 4 3/16", 7/16", 1 7/8" - 1.12 (unknown)
Justaneng - 8', 4", 7/8", 1 1/2" - 1.12 (Olhausen)
ShaneVanNothin - 9', 4 1/4", 1", 2" - 1.10 (Brunswick)
Neil - 7':0.85, 4 1/8", 1 1/4", 1 3/8" - 1.10 (Valley)
MahnaMahna - 10', 5 1/2", 2", 2 1/2" - 1.09 (converted from snooker table)
tjlmbklr - 8'+, 4", 141deg, 1 1/4" - 1.09 (unknown)
grobbs - 9', 4 1/4", 0.625", 1.5" - 1.09 (GC II)
Cardigan Kid - 9', 4 1/4", 0.45", 1 5/16" - 1.08 (GC II)
kanzzo - 9', 4 1/4", 5/8", 1" - 1.08 (GC V)
MSchaffer - 9', 4 7/16, 15/16", 1 5/8" - 1.07 (GC II)
cigardave - 9', 4 1/2", 1", 1 3/4" - 1.07 (Pro-Cut Diamond)
peppersauce - 9', 4 1/4", 3/8", 1 1/4" - 1.06 (GC III)
Side Pocket - 10', 4 7/8", 1", 1 1/2" - 1.05 (1920s Brunswick)
Pool Hustler - 9', 4 1/4", 1/4", 15/16" - 1.05 (GC)
IbeAnEngineer - 9', 4.5", 1.0", 1.5" - 1.05 (GC I)
JC - 9', 4 7/16", 143deg, 1 3/8" - 1.05 (GC III)
Banger - 9', 4 1/2", 7/8", 1 3/4" - 1.04 (GC III)
Jimmorrison - 7', 3 7/8", 7/16", 3/4" - 1.03 (Ruxton)
SloMoHolic - 9', 4 1/2", 7/8", 1 3/8" - 1.02 (Diamond Pro)
jondrums - 9', 11.9cm, 2.5cm, 4.2cm - 1.02 (Diamond Pro)
CoreyClark - 9', 5", 1", 2 1/8" - 1.02 (GC I)
bignick31985 - 9', 4 3/8", 0.475", 1.5" - 1.01 (GC IV)
"standard" table - 9', 4 7/16", 9/16", 1 5/8" - 1.00 (average-difficulty table)
Tennesseejoe- 9', 4.25", 1/4", 1 3/8" - 1.00 (1912 Brunswick Saratoga)
coxcol15 - 7', 4.25", 1", 1.25" - 1.00 (Valley with Ridgeback pro cuts)
Goldball - 8', 12.2cm, 4cm, 5.4cm - 1.00 (Heiron & Smith)
dr_dave - 9', 5", 1 1/8", 1 3/8" - 0.99 (GC II)
Call_me_Tom - 7', 4", 1/2", 1" - 0.99 (Valley with Penguin Pro rails)
MVPCues - 9', 4 1/2", 1/2", 1 5/8" - 0.98 (1902 Brunswick Jefferson)
oldschool1478 - 9', 4 1/2", 0.625", 1.5" - 0.98 (Diamond Pro)
freds - 8'+, 4.9", 1.1", 1.8" - 0.98 (Gandy Big G)
cjr3559 - 9', 4 1/2", 3/4", 1 1/4" - 0.97 (GC V - Tournament)
Cardigan Kid - 9', 4 1/2", 3/4", 1 1/16" - 0.97 (GC III)
wigglybridge - 9', 4 1/2", 5/8", 1 1/2" - 0.98 (rebuilt GC)
westcoast - 7', 4", 0", 1.5" - 0.98 (Valley)
BryanB - 9', 4 1/2"0, 3/4", 1 1/4" - 0.97 (1931 Brunswick)
Poolmanis - 9', 10.9cm, 1cm, 3.1cm - 0.97 (SAM)
Vahmurka - 9', 12.5cm, 20mm, 45mm - 0.97 (Brunswick Metro)
mamics - 9', 4 11/16", 143deg, 1 3/16" - 0.97 (no-name)
Will Maynard - 9', 4 3/4", 1", 3/4" - 0.97 (1904 Brunswick Narragansett)
dzcues - 9', 4 7/8", 11/16", 1 15/16" - 0.96 (Diamond)
jviss - 9’, 4.98”, 0.76”, 1.625” - 0.95 (GC I)
logical - 9', 5", 7/8", 1 3/4" - 0.95 (GC II)
dr_dave - 9', 5", 1", 1 1/5" - 0.95 (Olhausen)
dzcues - 9', 5", 15/16", 1 1/2" - 0.95 (Gandy Big G)
Sloppy Pockets - 8'+, 5", 1 1/8", 1 3/4" - 0.95 (A.E. Schmidt)
44Runner - 8', 4 3/8", 3/4", 1" - 0.94 (Diamond Pro-Am)
jtaylor-996 - 8' pro, 4.5", 0.5", 1.625" - 0.93 (Diamond)
Corwyn_8 - 9', 4 3/4", 1 3/4", 1 1/4" - 0.92 (Gandy Winchester)
beetle - 9', 13.1cm, 2.2cm, 4.3cm - 0.91 (Olhausen York)
frigopie - 9', 11.5cm, 138.7deg, 3.5cm - 0.91 (Eurotour Dynamic III)
12squared - 9', 4 7/8", 3/4", 1 1/2" - 0.91 (GC)
iusedtoberich - 9', 5 1/8", 1":, 1 1/2" - 0.90 (GC)
MSchaffer - 9', 5 1/8", 3/4", 1 3/4" - 0.89 (GC II)
mfinkelstein3 - 9', 5 1/8", 7/8", 1 1/2" - 0.88 (GC III)
StraightPoolIU - 9', 4 7/8", 3/4", 1 1/4" - 0.88 (GC I)
Vahmurka - 9', 5 1/8", 7/8", 1 1/2" - 0.88 (GC)
Dopc - 8', 4 1/2", 3/4", 1 1/4" - 0.87 (Connelly)
SloMoHolic - 8', 4 3/4", 3/4", 1 5/8" - 0.87 (Brunswick Medalist)
RobMan - 9', 5", 3/4", 1.5" - 0.86 (GC)
sniggihs - 7', 4 1/2", 5/8", 1 3/4" - 0.85 (Diamond)
SloMoHolic - 8'+, 4 7/8", 7/8", 1 1/4" - 0.85 (Brunswick Medalist)
buckshotshoey - 8', 4 3/4", 3/4", 1 1/2" - 0.85 (American Heritage)
nateobot - 7', 4 3/8", 1/2", 1 3/4" - 0.85 (custom)
angluse - 8'+, 4 5/8", 7/16", 1 3/16" - 0.84 (1935 Brunswick Challenger)
dr_dave - 8', 4 3/4", 5/8", 1 3/8" - 0.84 (Connelly)
BRussell - 8', 5", 13/16", 1 1/2" - 0.83 (Olhausen)
Lovepool - 9', 13cm, 1cm, 3.5cm - 0.82 (home)
jtaylor996 - 7', 5 1/8", 146deg, 1.51" - 0.82 (Legacy)
Mooneye - 7', 4 7/8", 3/4", 1 5/8" - 0.79 (Brunswick Ranchero)
SloMoHolic - 6', 4 1/2", 0", 5/8" - 0.77 (Valley)
dzcues - 7', 4 1/2", 0", 1/2" - 0.77 (Valley)
dr_dave - 7', 4 1/2", 0", 3/4" - 0.77 (Valley)
 
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GeoEnvi

Diamond System Enthusiast
Silver Member
My MS in Civil Engineering loves what you are doing, Dr. Dave!

I'd love to see how the local league tables stack up around here. I'm going to add a 6 inch engineering ruler to my cue case for measuring on the fly!

In my vocation, we use a similar method of combining partial factors of safety to get an overall factor of safety. Partial factors are usually empirically derived or manually set to get the 'spread' in the data that seems appropriate. I'm curious as to how you decided on the various Factor values...
 
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bdorman

Dead money
Silver Member
Very interesting. I can't wait to measure the table at our community center. I'm sure it's well under 1.0

The only limitation I see is using the table score to adjust the shooter's score. There is a very good chance that the shooter would have scored nearly as well on a more difficult table since most(?) of the drills are more about CB positioning than OB pocketing. Likewise, a shooter wouldn't necessarily score 20% higher on an easy table than he did on his tough table. You could probably apply another factor to account for pocketing vs. positioning, but I can feel Occam's Razor beginning to cut.
 

Jaden

"no buds chill"
Silver Member
I think this would only be the case...

Very interesting. I can't wait to measure the table at our community center. I'm sure it's well under 1.0

The only limitation I see is using the table score to adjust the shooter's score. There is a very good chance that the shooter would have scored nearly as well on a more difficult table since most(?) of the drills are more about CB positioning than OB pocketing. Likewise, a shooter wouldn't necessarily score 20% higher on an easy table than he did on his tough table. You could probably apply another factor to account for pocketing vs. positioning, but I can feel Occam's Razor beginning to cut.

I think that what you're describing would only be the case if you were attempting to discern the level of the player with this. It is more about the difficulty of the table.

There is room for improvement, but then you're getting too deep into the weeds. and it's time to take a drop.

I think what Dave has done here is great without getting too deep in the weeds.

Hell, I could see writing an app with this formula for checking a table on the fly.

Jaden
 

Mr. Bond

Orbis Non Sufficit
Gold Member
Silver Member
Dave, what is the presumed angle of the cushion facings?

And, do we not suppose that this angle is inconsistent from table to table?

And if so, does this angle not make a difference when it comes down to what stays in the pocket and what doesn't?
 

SpiderWebComm

HelpImBeingOppressed
Silver Member
There's so much that goes into how a table plays:

type of cloth, tightness of cloth, wear of cloth, type of rails, tightness of rails, type of balls, condition/cleanliness of balls, type of light, position of light, brightness/quality of light, cue ball type/size/condition, type of pocket facing/shim (material) and then, of course, the factors you pointed out with table size and pocket cut.

I see where you're going with the playability factor and it's not a bad idea --- I just think the conclusion can never be as specific as your example. Meaning, you can never say based on the 3 factors, table A plays 27% harder than table B.

The specificity of your result is just too great for something that is clearly subjective. You can never accurately ascertain exact factors since you're not dealing with tables made of the same material and manufactured the same way. For example, the pocket facings/shims can be made of different material and installed WAY differently from table to table and that plays a huge role is whether or not the pocket takes a shot.

Therefore, you can never have a result down to a single percentage and have it mean anything other than conjecture.

I don't think there's any way to scientifically determine table difficulty without having a player play the ghost 100 racks on table A and compare to table B. You might have a bar box that plays tough as hell (generally speaking) and a 5x10 that just accepts everything and has perfect speed.

The rating system would be more meaningful if you changed your calculations in order to reduce your resultants down to 5: super easy, easy, par, hard, very tough

How much harder (%-wise) is an easy table compared to a hard table? You'd never know without collecting data. Even then, you'd never have a margin of error within 1%. You'd have to round to the nearest 10 just to account for variation in a player's ability from day to day.
 
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dr_dave

Instructional Author
Gold Member
Silver Member
My MS in Civil Engineering loves what you are doing, Dr. Dave!
Thanks.

In my vocation, we use a similar method of combining partial factors of safety to get an overall factor of safety.

I'm curious as to how you decided on the various Factor values...
The table size factor (TSF) was easy. Shot difficulty is directly related to shot distance which is directly related to table size on average, so I just had to look at percentage changes in table size and round off. The pocket size factor (PSF) was also easy. If you look at the effective size of the pocket (i.e., how much you can be off in either direction and still pocket the ball), I just calculated the percentage change associated with each pocket size, and rounded off.

The pocket angle factor (PAF) and Pocket Shelf Factor (PSF) were a little trickier. Luckily, I've done an extensive analysis on these effects in the past. For more info, see the pocket "size" and "center" resource page. I used my TP 3.6 document to analyze changes in each pocket spec. I also interviewed several experienced players asking for their gut feel on each factor. And then I rounded off some.

I also did some calculations on a few tables to see if they came out about where I thought they should. For example, this is what I got for my home table:
size: 8', mouth: 4 3/4", throat: 4 1/8", (mouth-throat): 5/8", shelf: 1 3/8"
TSF=0.90, PSF=1.00, PAF=1.00, PLF=0.95
TDF = TSF x PSF x PAF x PLF = 0.90 x 1.00 x 1.00 x 0.95 = 0.81

and this is what I got for my VNEA league's Valley/Dynamo "bar boxes:"
size: 7', mouth: 4 1/2", throat: 4 1/2", (mouth-throat): 0", shelf: 3/4"
TSF=0.80, PSF=1.05, PAF=0.94, PLF=0.90
TDF = TSF x PSF x PAF x PLF = 0.80 x 1.05 x 0.94 x 0.90 = 0.71

Both of these numbers seemed appropriate to me. My home table seems about 20% easier than standard, and the bar box seems about 30% easier than standard, in general (although the numbers might be a little high). The best test would be to have a bunch of people do the BU Exams on various tables and correlate the factors with the scores. I plan to do this for myself and my students in the future. I also hope some AZBers do the same and share their results.

I look forward to getting feedback from AZB'ers after they take measurements on their favorite tables and comment on how well the TDF matches what they perceive.

Catch you later,
Dave
 
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GeoEnvi

Diamond System Enthusiast
Silver Member
Not likely applicable for adjusting the scores from the BU tests, as they tend to require hitting to the same pocket, but perhaps there's another factor?

Pocket Variability Factor (PVF) - Adjusts for the variability in the other factors as you move around the table from one pocket to another.

On a poorly set-up bar table, you might have mis-matched rails or uneven pocket cuts that result in each of the pocket's measurements not being alike. If I was trying to quantify the TDF for all the tables in my league, this might be an important extra factor for fitting them all into a model.
 

Jaden

"no buds chill"
Silver Member
That's what I meant by getting too deep into the weeds...

There's so much that goes into how a table plays:

type of cloth, tightness of cloth, wear of cloth, type of rails, tightness of rails, type of balls, condition/cleanliness of balls, type of light, position of light, brightness/quality of light, cue ball type/size/condition, type of pocket facing/shim (material) and then, of course, the factors you pointed out with table size and pocket cut.

I see where you're going with the playability factor and it's not a bad idea --- I just think the conclusion can never be as specific as your example. Meaning, you can never say based on the 3 factors, table A plays 27% harder than table B.

The specificity of your result is just too great for something that is clearly subjective. You can never accurately ascertain exact factors since you're not dealing with tables made of the same material and manufactured the same way. For example, the pocket facings/shims can be made of different material and installed WAY differently from table to table and that plays a huge role is whether or not the pocket takes a shot.

Therefore, you can never have a result down to a single percentage and have it mean anything other than conjecture.

I don't think there's any way to scientifically determine table difficulty without having a player play the ghost 100 racks on table A and compare to table B. You might have a bar box that plays tough as hell (generally speaking) and a 5x10 that just accepts everything and has perfect speed.

The rating system would be more meaningful if you changed your calculations in order to reduce your resultants down to 5: super easy, easy, par, hard, very tough

How much harder (%-wise) is an easy table compared to a hard table? You'd never know without collecting data.

It's going to have a lot to do with the type of player, do they finesse the balls, do they slam everything, do they try to play pinpoint shape, do they shoot for general areas???

There is an nth degree of depth to the level of difficulty a certain table plays for different players.

For a while I couldn't play well on a diamond proam because I was used to shooting for center pocket, and I couldn't understand why I could consistently run out on a gold crown with 3 7/8" pockets but would hang balls on a 4.5" diamond.

I've adjusted because I realized that I have to shoot for a specific part of the pocket on a diamond and not just shoot center pocket on every shot.

I don't necessarily like it, it adds a different dimension to the game, but I can play well on a diamond now though.

That's why I preferred the tight pockets of the diamond that Glen did up at the golden fleece, I could aim for center pocket and fire away...

Of course, from what I understand, they only allow one hole on that table now...I got to play rotation games on it after it was first done though...

Jaden
 

dr_dave

Instructional Author
Gold Member
Silver Member
Very interesting. I can't wait to measure the table at our community center. I'm sure it's well under 1.0
Please post the info and your impressions after you do this.


The only limitation I see is using the table score to adjust the shooter's score. There is a very good chance that the shooter would have scored nearly as well on a more difficult table since most(?) of the drills are more about CB positioning than OB pocketing. Likewise, a shooter wouldn't necessarily score 20% higher on an easy table than he did on his tough table. You could probably apply another factor to account for pocketing vs. positioning, but I can feel Occam's Razor beginning to cut.
Well stated. I agree completely ... especially concerning "Occam's Razor." ;)

Regards,
Dave
 

Mr. Bond

Orbis Non Sufficit
Gold Member
Silver Member
There's so much that goes into how a table plays:

type of cloth, tightness of cloth, wear of cloth, type of rails, tightness of rails, type of balls, condition/cleanliness of balls, type of light, position of light, brightness/quality of light, cue ball type/size/condition, type of pocket facing/shim (material) and then, of course, the factors you pointed out with table size and pocket cut.

I see where you're going with the playability factor and it's not a bad idea --- I just think the conclusion can never be as specific as your example. Meaning, you can never say based on the 3 factors, table A plays 27% harder than table B.

The specificity of your result is just too great for something that is clearly subjective. You can never accurately ascertain exact factors since you're not dealing with tables made of the same material and manufactured the same way. For example, the pocket facings/shims can be made of different material and installed WAY differently from table to table and that plays a huge role is whether or not the pocket takes a shot.

Therefore, you can never have a result down to a single percentage and have it mean anything other than conjecture.

I don't think there's any way to scientifically determine table difficulty without having a player play the ghost 100 racks on table A and compare to table B. You might have a bar box that plays tough as hell (generally speaking) and a 5x10 that just accepts everything and has perfect speed.

The rating system would be more meaningful if you changed your calculations in order to reduce your resultants down to 5: super easy, easy, par, hard, very tough

How much harder (%-wise) is an easy table compared to a hard table? You'd never know without collecting data. Even then, you'd never have a margin of error within 1%. You'd have to round to the nearest 10 just to account for variation in a player's ability from day to day.

I hear what you're saying and I agree. But, the pocket information is not without merit.
It is real and relevant, and without a doubt, gives you very specific insight as to how a table will play, regardless of the various other factors involved. Is the pocket info all that matters ? Certainly not, but at the same time, having this information is certainly better than not having it.
 

GeoEnvi

Diamond System Enthusiast
Silver Member
Dave, what is the presumed angle of the cushion facings?

And, do we not suppose that this angle is inconsistent from table to table?

And if so, does this angle not make a difference when it comes down to what stays in the pocket and what doesn't?

I think the Table Angle Factor takes care of the presumed angle of cushion facings.

Clearly, the shallower angle facings have higher difficulty factor than the steeper facings. Makes sense to me, given that a shallower cut would likely deflect a ball more toward the other facing than the shelf. Unless I'm getting it backwards, a shallower cut would result in more 'rattles' than a steeper cut for the same shelf.
 

dr_dave

Instructional Author
Gold Member
Silver Member
I think that what you're describing would only be the case if you were attempting to discern the level of the player with this. It is more about the difficulty of the table.

There is room for improvement, but then you're getting too deep into the weeds. and it's time to take a drop.

I think what Dave has done here is great without getting too deep in the weeds.
Thanks for the input. I agree.

Hell, I could see writing an app with this formula for checking a table on the fly.
That's a great idea. Do it.

Catch you later,
Dave
 

Bob Jewett

AZB Osmium Member
Staff member
Gold Member
Silver Member
... I will be curious to see what you guys think, and I look forward to your suggestions and feedback. ...
I think that the ideal measure would be the size of the pocket as a function of speed, angle and spin on the shot but that is much, much harder to measure than the factors above. It also has a lot more dimensions. It would be nice to have a comparison of the two methods over a variety of tables, but that's probably a few-month project.

As pointed out above, lousy pocket facings can make a table play much more difficult on some shots but I see no easy way to quantify that other than by a lot of shots to determine the effective pocket size.
 

dr_dave

Instructional Author
Gold Member
Silver Member
Dave, what is the presumed angle of the cushion facings?
The angle is not presumed ... it is determined from the (mouth - throat) difference. For the "standard" table (PAF = 1.00), the pocket angle is close to the WPA spec (142 degrees).

And, do we not suppose that this angle is inconsistent from table to table?
The pocket angle can vary significantly among different table brands, models, and builds.

And if so, does this angle not make a difference when it comes down to what stays in the pocket and what doesn't?
The pocket angle can make a big difference. That's what the "pocket angle factor (PAF)" is for.

Regards,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
There's so much that goes into how a table plays:

type of cloth, tightness of cloth, wear of cloth, type of rails, tightness of rails, type of balls, condition/cleanliness of balls, type of light, position of light, brightness/quality of light, cue ball type/size/condition, type of pocket facing/shim (material) and then, of course, the factors you pointed out with table size and pocket cut.
I agree completely. Humidity can also play a large role. However, the TDF at least gives us a "base line" that includes important and easily measurable factors without getting ridiculously complex.

I see where you're going with the playability factor and it's not a bad idea
Thank you.

I just think the conclusion can never be as specific as your example. Meaning, you can never say based on the 3 factors, table A plays 27% harder than table B.
Actually, it is 4 factors, but your point is well taken ... I agree.

The specificity of your result is just too great for something that is clearly subjective.
The numbers are meant to provide a rough comparison. They shouldn't be interpreted too literally; although, I can see how somebody might take it that way. BTW, the numbers aren't entirely "subjective" based on my reply to GeoEnvi. Check it out.

You can never accurately ascertain exact factors since you're not dealing with tables made of the same material and manufactured the same way. For example, the pocket facings/shims can be made of different material and installed WAY differently from table to table and that plays a huge role is whether or not the pocket takes a shot.

Therefore, you can never have a result down to a single percentage and have it mean anything other than conjecture.
Agreed; although the four factors do a decent job assessing many of the important factors.

I don't think there's any way to scientifically determine table difficulty without having a player play the ghost 100 racks on table A and compare to table B. You might have a bar box that plays tough as hell (generally speaking) and a 5x10 that just accepts everything and has perfect speed.
This would be the best way to test and improve the system. That's why I suggest what I do at the end of my reply to GeoEnvi.

The rating system would be more meaningful if you changed your calculations in order to reduce your resultants down to 5: super easy, easy, par, hard, very tough
That's a good idea. Maybe I'll add that to the document.

How much harder (%-wise) is an easy table compared to a hard table? You'd never know without collecting data.
I agree; although, the analysis I've done is somewhat quantitative and takes real effects into consideration.

Even then, you'd never have a margin of error within 1%. You'd have to round to the nearest 10 just to account for variation in a player's ability from day to day.
I agree completely.

Thank you for your excellent insight and suggestions,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
There's so much that goes into how a table plays:

type of cloth, tightness of cloth, wear of cloth, type of rails, tightness of rails, type of balls, condition/cleanliness of balls, type of light, position of light, brightness/quality of light, cue ball type/size/condition, type of pocket facing/shim (material) and then, of course, the factors you pointed out with table size and pocket cut.

I see where you're going with the playability factor and it's not a bad idea --- I just think the conclusion can never be as specific as your example. Meaning, you can never say based on the 3 factors, table A plays 27% harder than table B.

The specificity of your result is just too great for something that is clearly subjective. You can never accurately ascertain exact factors since you're not dealing with tables made of the same material and manufactured the same way. For example, the pocket facings/shims can be made of different material and installed WAY differently from table to table and that plays a huge role is whether or not the pocket takes a shot.

Therefore, you can never have a result down to a single percentage and have it mean anything other than conjecture.

I don't think there's any way to scientifically determine table difficulty without having a player play the ghost 100 racks on table A and compare to table B. You might have a bar box that plays tough as hell (generally speaking) and a 5x10 that just accepts everything and has perfect speed.

The rating system would be more meaningful if you changed your calculations in order to reduce your resultants down to 5: super easy, easy, par, hard, very tough

How much harder (%-wise) is an easy table compared to a hard table? You'd never know without collecting data. Even then, you'd never have a margin of error within 1%. You'd have to round to the nearest 10 just to account for variation in a player's ability from day to day.

I hear what you're saying and I agree. But, the pocket information is not without merit.
It is real and relevant, and without a doubt, gives you very specific insight as to how a table will play, regardless of the various other factors involved. Is the pocket info all that matters ? Certainly not, but at the same time, having this information is certainly better than not having it.
Excellent post.

Thank you,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
I think that the ideal measure would be the size of the pocket as a function of speed, angle and spin on the shot but that is much, much harder to measure than the factors above. It also has a lot more dimensions. It would be nice to have a comparison of the two methods over a variety of tables, but that's probably a few-month project.

As pointed out above, lousy pocket facings can make a table play much more difficult on some shots but I see no easy way to quantify that other than by a lot of shots to determine the effective pocket size.
As usual, I agree with you 100%.

Thanks for the input,
Dave
 

SpiderWebComm

HelpImBeingOppressed
Silver Member
I agree completely. Humidity can also play a large role. However, the TDF at least gives us a "base line" that includes important and easily measurable factors without getting ridiculously complex.

Thank you.

Actually, it is 4 factors, but your point is well taken ... I agree.

The numbers are meant to provide a rough comparison. They shouldn't be interpreted too literally; although, I can see how somebody might take it that way. BTW, the numbers aren't entirely "subjective" based on my reply to GeoEnvi. Check it out.

Agreed; although the four factors do a decent job assessing many of the important factors.

This would be the best way to test and improve the system. That's why I suggest what I do at the end of my reply to GeoEnvi.

That's a good idea. Maybe I'll add that to the document.

I agree; although, the analysis I've done is somewhat quantitative and takes real effects into consideration.

I agree completely.

Thank you for your excellent insight and suggestions,
Dave

You must have a masters degree in line-item quotations and response "break-downs."

You have a ways to go yet, however, until you have a doctoral-level like your boy Patrick Johnson. He's definitely the 7-ball above you at that!
 

dr_dave

Instructional Author
Gold Member
Silver Member
Dave, what is the presumed angle of the cushion facings?

And, do we not suppose that this angle is inconsistent from table to table?

And if so, does this angle not make a difference when it comes down to what stays in the pocket and what doesn't?
It's incorporated by the "Pocket Angle Factor", isn't it?
Yes.

But I see a weakness in this because, in reality, it isn't a smooth progression of difficulty. It hits an increasing "go"/"no go" point which can't be captured by this measurement.
Are you suggesting that the PAF should be much higher at the higher mouth/throat differences?

BTW, the "go/no-go" effect applies only for shots going off the points or close to the rails, right? Remember, the PAF is an average number over the full range of possible shots.

Please elaborate more on the "go/no-go" effect and how you think the PAF values could be improved.

Thanks,
Dave
 
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