Based on ideas from previous threads on this topic (
tight pockets thread and
pocket answers thread), and based discussion in the
Billiard University (BU) thread concerning how to account for table difficulty in scoring and rating drills like the
BU Exams, I decided to create a system for determining how difficult a table plays. It is described in detail in the
Table Difficulty Factor (TDF) document, which is convenient if you want a printed copy.
Here's how it works:
The
Table Difficulty Factor (TDF) is a percentage measure of how difficult or easy a particular table plays. It is based on table size and the three corner-pocket measurements illustrated below. Four factors are used to account for table size, pocket size, pocket wall angle, and pocket shelf depth. Each factor is a number less than, equal to, or greater than 1, where 1 indicates average or standard. By multiplying the four factors, you get the TDF which is a good measure of table “toughness.” If TDF=1, the table has an average level of difficulty; if TDF>1, the table plays more difficult than average; and if TDF<1, the table plays easier than average.
The four factors are defined as follows:
The total
Table Difficulty Factor (TDF) is then calculated by multiplying the four factors:
TDF = TSF x PSF x PAF x PLF
The TDF can be used to adjust numbers from any scoring or rating system like the
Billiard University Exams,
“playing the ghost” drills,
Hopkins Q Skills drill, or the Fargo
rating drill or
handicapping system. An effective score, taking table difficulty into consideration, can be calculated with:
(effective score) = (raw score) x TDF
Here's an example of how the TDF system is used. Let’s say two players (“A” and “B”) got an identical
Billiard University (BU) score of 130. Player “A” took the exams on a fairly “easy” table with the following measurements:
Table “A”
table size = 8’, mouth = 5”, throat = 4 1/2”, (mouth-throat) = 1/2”, shelf = 1 3/8”
TDF = TSF x PSF x PAF x PLF = 0.90 x 0.95 x 1.00 x 0.95 = 0.81
Therefore, table “A” is about 19% easier than average, and the effective BU score on this table would be 130 x 0.81 = 105 (much lower than 130).
Player “B” took the exams on a fairly “tough” table with the following measurements:
Table “B”
table size = 9’, mouth = 3 7/8”, throat = 3 1/4”, (mouth-throat) = 5/8”, shelf = 1 7/8”
TDF = TSF x PSF x PAF x PLF = 1.00 x 1.20 x 1.03 x 1.05 = 1.30
Therefore, table “B” is about 27% more difficult than average, and the effective BU score on this table would be 130 x 1.30 = 169 (much higher than 130). This helps put the BU scores in better perspective based on table difficulty.
I will be curious to see what you guys think, and I look forward to your suggestions and feedback.
Thank you,
Dave
