AzBilliards.com Table Difficulty Factor (TDF) for measuring table "toughness"
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(#16)
dr_dave
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06-21-2013, 09:18 AM

Quote:
 Originally Posted by SpiderWebComm 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.

Quote:
 Originally Posted by SpiderWebComm I see where you're going with the playability factor and it's not a bad idea
Thank you.

Quote:
 Originally Posted by SpiderWebComm 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.

Quote:
 Originally Posted by SpiderWebComm 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.

Quote:
 Originally Posted by SpiderWebComm 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.

Quote:
 Originally Posted by SpiderWebComm 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.

Quote:
 Originally Posted by SpiderWebComm 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.

Quote:
 Originally Posted by SpiderWebComm 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.

Quote:
 Originally Posted by SpiderWebComm 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

(#17)
dr_dave
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06-21-2013, 09:20 AM

Quote:
Originally Posted by Mr. Bond
Quote:
 Originally Posted by SpiderWebComm 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

(#18)
dr_dave
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06-21-2013, 09:22 AM

Quote:
 Originally Posted by Bob Jewett 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

(#19)
SpiderWebComm
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06-21-2013, 09:28 AM

Quote:
 Originally Posted by dr_dave 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!

(#20)
dr_dave
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06-21-2013, 09:30 AM

Quote:
Originally Posted by Bob Dixon
Quote:
 Originally Posted by Mr. Bond 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.

Quote:
 Originally Posted by Bob Dixon 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

(#21)
dr_dave
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06-21-2013, 09:33 AM

Quote:
 Originally Posted by SpiderWebComm 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!
Thanks. That's funny.

Catch you later,
Dave

PS: Have you tried the BU Exams yet. If so, please consider posting your score (and videos if available) on the BU thread. Thanks!

 (#22) Neil AzB Silver Member   Status: Offline Posts: 17,598 vCash: 2200 iTrader: 2 / 100% Join Date: Jan 2007 06-21-2013, 09:40 AM Mine was done on a modified 7' table. Score of 141, effective score of 130.3. All things exactly the same on pockets, only on a 9' table, effective score of 162.8. No way just a 7' to a 9' is worth 31.5 points! Especially when on a lot of shots, the pocket size either isn't much of a factor, or is essentially no factor at all. Sorry Dave, but I don't think the system makes a fair correlation between table sizes. However, it does between tables of the same size to a certain degree. Just how much that degree is, is questionable. You also have to take into account the margin of error for different angle shots, and different distance of shots. A whole lot to really take into consideration. So much, that I'm not sure it would even be worth it to really get an accurate comparison. For example- I have a 30 degree shot to the corner. If it is near the pocket, I have a much larger margin of error than if it is far from the pocket. So, on a 7' table, I have a larger margin of error than on a 9' table with both ob,s at center table, and both cb's two diamonds away with pockets of the same size. But, how does the margin of error really equate with pocket size? It will vary according to the distance, and the angle to the pocket. If the ball is near the rail, say a ball width off the rail, now you have to consider the springiness of the rail. Soft rails will allow you to have a much larger margin of error on the shot than bouncy rails will. So, pocket size is not the only consideration. In your drill test, take the stop shots. I can hit every one absolutely perfect, stopping stone cold dead on contact, and still get a lower score than someone on a 9' table that actually miss-hits every single shot so that the cb hits the rail and rebounds to the acceptable target zone. With that shot, pocket size is going to have very, very, little effect on making or missing the shot until you get down to a pocket size very close to the ob size.
(#23)
SpiderWebComm
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06-21-2013, 09:42 AM

Quote:
 Originally Posted by dr_dave Thanks. That's funny. Catch you later, Dave PS: Have you tried the BU Exams yet. If so, please consider posting your score (and videos if available) on the BU thread. Thanks!
I've worked up the following equation to figure out the relationship between the scoring data and my interest:

I'm still trying to figure out why it always returns 0. I'll keep working on it

 (#24) iusedtoberich AzB Silver Member   Status: Offline Posts: 11,177 vCash: 1470 iTrader: 20 / 100% Join Date: Mar 2004 06-21-2013, 09:46 AM Dr Dave, I like very much what you are attempting to do. I have a few comments, but I will have to read through what you did thus far first, so that I can make an informed comment. One quick comment I'd like to make, is of course there are other things missing that determine how tough a table plays. But, one common factor in almost any comparison, is to be able to measure and put a number to it. Even if that is a simple as asking a person on a scale of 1-5 how hard this table plays, all things considered. Without having a number, it is very difficult if not impossible to measure improvement, or variations. The formulas to get the numbers can be refined over time. But with no numbers to start with, its just more black magic type stuff. This is one thing that bugs me so much about tables. A mechanic or player will say "this table plays the way its supposed to", but there is none or little numbers behind that, which leads to the understanding of WHY the table might play that way, and why another one does not. IMO, the biggest recent debate on this is diamond rails vs GC rails and how the balls react off of them.
 (#25) BRussell AzB Silver Member     Status: Offline Posts: 3,607 vCash: 500 iTrader: 0 / 0% Join Date: Apr 2013 06-21-2013, 09:48 AM Nice job Dave! It would be nice to have some empirical validation that this translates into actual difficulty. It would be possible to see how people's BU scores change, or "ghost to 100," but because this TDF focuses so much on pocketing difficulty, I don't think that would be necessary. Instead, to speed things up, you could use the pocketing portion of the BU test, which only takes a few minutes. It would be cool to see how well your TDF predicts changes in the number of balls made. My guess is that it would do pretty well.
(#26)
dr_dave
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06-21-2013, 09:53 AM

Quote:
 Originally Posted by Neil Mine was done on a modified 7' table. Score of 141, effective score of 130.3. All things exactly the same on pockets, only on a 9' table, effective score of 162.8. No way just a 7' to a 9' is worth 31.5 points!
It's not that simple. On a 9' table, you would have been able to take the Doctorate Exam instead, which has more points available (albeit with greater difficulty level also). On the other hand, with those tight pockets on a 9' table, some shots (even the stop/follow-draw shots) might rattle due to the larger distances and additional precision required. But again, it's not that simple.

Quote:
 Originally Posted by Neil Especially when on a lot of shots, the pocket size either isn't much of a factor, or is essentially no factor at all.
I disagree. For people who aren't as accurate as you, both table size and pocket size make a huge difference, especially on bigger tables with tighter pockets.

Quote:
 Originally Posted by Neil Sorry Dave, but I don't think the system makes a fair correlation between table sizes. However, it does between tables of the same size to a certain degree. Just how much that degree is, is questionable.
I agree about the "questionable" part, but I had to start somewhere.

Quote:
 Originally Posted by Neil You also have to take into account the margin of error for different angle shots, and different distance of shots. A whole lot to really take into consideration. So much, that I'm not sure it would even be worth it to really get an accurate comparison. For example- I have a 30 degree shot to the corner. If it is near the pocket, I have a much larger margin of error than if it is far from the pocket. So, on a 7' table, I have a larger margin of error than on a 9' table with both ob,s at center table, and both cb's two diamonds away with pockets of the same size. But, how does the margin of error really equate with pocket size? It will vary according to the distance, and the angle to the pocket. If the ball is near the rail, say a ball width off the rail, now you have to consider the springiness of the rail. Soft rails will allow you to have a much larger margin of error on the shot than bouncy rails will.
Neil, good points; but the point of the TDF system isn't to describe difficulty level of individual shots. The purpose is to describe the average over a wide range of shots, and do so with as few measurements and calculations as possible to get a rough estimate for table difficulty. I think the current TDF system does a decent job at that; although, there is certainly room for improvement. It also needs to be tested thoroughly to be able to make meaningful improvements.

Thanks for you input,
Dave

(#27)
dr_dave
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06-21-2013, 09:57 AM

Quote:
Originally Posted by SpiderWebComm
Quote:
 Originally Posted by dr_dave Have you tried the BU Exams yet. If so, please consider posting your score (and videos if available) on the BU thread. Thanks!
I've worked up the following equation to figure out the relationship between the scoring data and my interest:

I'm still trying to figure out why it always returns 0. I'll keep working on it
I think your formula has an attitude problem. Maybe you should try something simpler and more mature.

I hope you reconsider. I thought you were into this sort of thing (playing ability tests and rating systems ... not formulas). You certainly have been in the past with other playing-ability drills posted. I guess it must be me you don't like.

Catch you later,
Dave

(#28)
dr_dave
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06-21-2013, 09:58 AM

Quote:
 Originally Posted by iusedtoberich Dr Dave, I like very much what you are attempting to do. I have a few comments, but I will have to read through what you did thus far first, so that I can make an informed comment. One quick comment I'd like to make, is of course there are other things missing that determine how tough a table plays. But, one common factor in almost any comparison, is to be able to measure and put a number to it. Even if that is a simple as asking a person on a scale of 1-5 how hard this table plays, all things considered. Without having a number, it is very difficult if not impossible to measure improvement, or variations. The formulas to get the numbers can be refined over time. But with no numbers to start with, its just more black magic type stuff. This is one thing that bugs me so much about tables. A mechanic or player will say "this table plays the way its supposed to", but there is none or little numbers behind that, which leads to the understanding of WHY the table might play that way, and why another one does not. IMO, the biggest recent debate on this is diamond rails vs GC rails and how the balls react off of them.
Thanks for your input. I look forward to any additional feedback you might have after you look at the details and try it out.

Catch you later,
Dave

(#29)
dr_dave
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06-21-2013, 10:04 AM

Quote:
 Originally Posted by BRussell Nice job Dave!
Thanks!

Quote:
 Originally Posted by BRussell It would be nice to have some empirical validation that this translates into actual difficulty. It would be possible to see how people's BU scores change, or "ghost to 100," but because this TDF focuses so much on pocketing difficulty, I don't think that would be necessary. Instead, to speed things up, you could use the pocketing portion of the BU test, which only takes a few minutes. It would be cool to see how well your TDF predicts changes in the number of balls made. My guess is that it would do pretty well.
Good idea. I would love to see some data like this. I plan to generate some on my own, but I hope others will also. That would be great if people would post well-practiced BU scores (or partial scores) on different equipment. Please post results if you try some experiments.

Thank you for the feedback and input,
Dave

 (#30) bstroud AzB Silver Member   Status: Offline Posts: 826 vCash: 500 iTrader: 5 / 100% Join Date: Dec 2004 06-21-2013, 10:16 AM Dr. Dave, Something you seem to be missing are the balls. Perhaps it's just me (I quit playing for 30 so years) but the Aramith balls play completely different than the original Centennials. They kick or skid ALL the time. They turn over much more and the cut angle needs to be much thinner. If there is a trick to playing with them I would sure like to know. Bill S.
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