User:Ricw147/sandbox

 Ricw147’s Snooker Grading System

Synopsis

This document details a system to measure and grade an “average to good” snooker player’s performance for any given session of snooker. The system is ideally suited for players who play against each other on a regular basis.

The system was devised by 2 former snooker league players, Ric L. Washer and Jeremy Lewis and was enhanced further following weekly sessions played at ‘Redz’ snooker hall in Cwmbran, South Wales.

The system is based on the result of a session, the points scored and the breaks made by the individual players. From the frame scores and breaks, grade points are calculated and subsequently a performance “grade” can be awarded, ranging from A* down to F.

The system uses a calculation formula incorporating a ‘constant’, which is pre-defined and common throughout all sessions in which the players use the system. This constant is known as the ‘BASE’.

In order to work out the BASE initially, an advisable method may be for players to play a few sessions together and then work out their average frame score they are achieving. This frame average is used as the BASE.

This BASE can then be reassessed at the end of a given period and adjusted if required. i.e. if a BASE was adopted and then the players were both consistently achieving grades of ‘B’ and above every session, then perhaps the BASE was set too low initially. Likewise, if the players are both consistently achieving grades of ‘D’ or below, then perhaps the BASE was set too high.

An example of a feasible BASE is 50.0. I have suggested 50.0 based on the fact that even for a professional player, although their scoring in a frame may frequently exceed 100 points, there are also frames in which a professional player will score 0 points. The average therefore in this scenario (of 100 and 0) is 50.0. From research on the WPSBA web-site, in recent years the average frame score for a professional player was around the 54 – 55 mark.

The system variables and what to record

Frames are played using the normal snooker rules with the frame scores and any breaks made over 20 being recorded per frame per player. To calculate a player’s performance grade, we use the data to firstly calculate the player’s grade points for that session and then award a grade accordingly.

At the end of the session, the number of frames each player has won and lost it noted. This will give the players a ‘+’ or ‘-‘ “Frame Difference” value. e.g. a 4 v 2 result will give player A having +2 and player B –2. The result may be a draw, if an even number of frames were played and both players won/lost the same amount. The Frame Difference for both players in this scenario would be 0.

Each player has a grand total of all the points they have scored in the session. Dividing the player’s total points scored by the number of frames played will give the players their average frame score. This is know is the player’s “Session Average”.

ALL breaks made over 20 are awarded a Break Bonus (BB) with EACH 20 - 29 break scoring 0.5 break bonus; EACH 30 - 39 break scoring 1.0 break bonus; EACH 40 - 49 break scoring 1.5 break bonus; EACH 50 - 59 break scoring 2.0 break bonus; EACH 60+ break scoring 3.0 break bonus. In addition, if a player has made a ‘clearance’ of 25 or more, an additional 0.25 is added AS WELL AS the Break Bonus for that clearance.

Calculating the Grade Points

To work out the grade points for each player, use the formula : - (Players “Session Average” - BASE) + (Frame Difference) + (TOTAL of all break bonuses attained BB). This can therefore be expressed as GP = (PSA - BASE) + (FD) + (BB).

An example of an “average” performance for a player may be that they achieved a Session Average frame score equal to that of the BASE. A Frame Difference of 0 (i.e. a drawn results in frames) and they made at least 1 x 20-29 break. This would give the player Grade Points of 0.5 and therefore (with the 20-29 break) a grade ‘C’. However 0.5 points could be the grade points if the player achieved a lower session average, a positive Frame Difference and made several breaks. Likewise, a high session average, a negative Frame Difference and only 1 break, but still giving 0.5 grade points and a grade ‘C’. Grade Table

The table below shows the grade points range, with the different grades being awarded based on the grade points AND the player’s highest break in that session.

N.B The grade is calculated based on both the player’s Grade Points AND the Highest Break (HB) that the player achieved in that session.

This table shows values gauged for a player with good all-round ability **.

Positive Grade Points Range	HB		Grade --			--- >12.00	(elite)	 		40+		A* >12.00	(elite)			30-39		A+ >12.00 standard		20-29		A >12.00				no break	C- >10.00 to 11.99			>30		A >10.00 to 11.99 standard	>20-29		A- >10.00 to 11.99			no break	C- >8.00 to 9.99			>30		A- >8.00 to 9.99 standard		>20-29		B+ >8.00 to 9.99			no break	C- >6.00 to 7.99			>30		B+ >6.00 to 7.99 standard		>20-29		B >6.00 to 7.99			no break	C- >4.00 to 5.99			>30		B >4.00 to 5.99 standard		>20-29		B- >4.00 to 5.99			no break	C- >2.00 to 3.99			>30		B- >2.00 to 3.99 standard		>20-29		C+ >2.00 to 3.99			no break	C- >0 to 1.99			>30		C+ >0 to 1.99 standard		>20-29		C (‘average performance’) >0 to 1.99			no break	C-

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Negative Grade Points Range	HB		Grade ---			--- <0 to -1.99			>30		C <0 to -1.99 standard		>20-29		C- <0 to -1.99			no break	D+ <-2.00 to -3.99			>30		C- <-2.00 to -3.99 standard		>20		D+ <-2.00 to -3.99			no break	D <-4.00 to -5.99			>30		D+ <-4.00 to -5.99 standard		>20		D <-4.00 to -5.99			no break	D- <-6.00 to -7.99			>30		D <-6.00 to -7.99 standard		>20		D- <-6.00 to -7.99			no break	E+ <-8.00 to -9.99			>30		D- <-8.00 to -9.99 standard		>20		E+ <-8.00 to -9.99			no break	E <-10.00 to -11.99		>30		E+ <-10.00 to -11.99 standard	>20		E <-10.00 to -11.99		no break	E- <-12.00 to -13.99		>30		E <-12.00 to -13.99 standard	>20		E- <-12.00 to -13.99		no break	F+ <-14.00				>30		E- <-14.00 standard		>20		F+ <-14.00				no break	F

Grade Ruling (Ability Level Incremental Adjustments)

The ‘standard’ level for an ‘average to good’ player is based on the player consistently having breaks in the 20-29 region. For any session where a player’s HB is 30 or more, their grade will be increased within the grade point range. i.e. if a player’s grade points were +6.5 and their HB was 32, the grade will be increased from a ‘B‘ to ‘B+’. In other words the “upper limit” grade for that grade point range.

Capping the Grades/ Null

Any session in which the player fails to make a break of 20 or more will be deemed “sub standard” and a -2.0 points penalty is applied to their grade points total for that session. A session of this nature is known as a ‘NULL’. All 'positive' grade points (i.e. +0.01 or above) but with no break (NULL), will be capped at a “C-“ grade. All 'negative' grade points (i.e. -0.01 or below) and with no break (NULL), will be decreased down within the grade point range. i.e. if a player’s grade points were -6.5 and they did not make a 20 break or more, the grade would be decreased from ‘D-‘ to ‘E+’. The highest possible grade if the player does not make at least a 20+ break in a session will be a ‘C-‘ grade. The lowest is an ‘F’ grade.

Exception

For the lowest grade of ‘F’, this will ONLY be given if the player achieved grade points of -14.00 or less, AND did NOT make a break over 20 in the session (NULL). If the player achieved less than -14.00 grade points but did succeed in hitting a break between 20-29, the grade will be increased to an ‘F+. This would be increasing further still to ‘E-‘ if the HB in the session was over 30.

Elite Grade ‘A*’ and ‘A+’ Ruling

For the higher grade points of +12.00 and above, an extra ruling applies. This ruling caters for the scenario where a player continues to pot balls after a frame is already lost, with the view of increasing their overall session total and subsequently their session average. The rule prevents an ‘A*’ or ‘A+’ grade being awarded based purely on the grade points the player scored in the session. An ‘A*’ grade will ONLY be awarded if the player achieves over +12.00 grade points AND their HB in the session is over 40. An ‘A+’ grade will ONLY be awarded if the player achieves over +12.00 grade points AND their HB in the session is between 30 – 39. An ‘A’ grade will be awarded if player achieves over +12.00 grade points AND their HB in the session is between 20 – 29 (standard). If the player achieved over 12.00+ grade points but failed to hit at least a 20 break, the grade would be capped as a ‘C-‘ grade.

Adaptable for all levels

The system can be adapted for players of different ability. The variables, formula and system grades remain the same, as does the BASE (which would have been pre-defined) and the break bonuses, but dependant on the player’s ability, the “upper”, “standard” and “no breaks” levels can be adjusted accordingly.

i.e for very good club players, change the “standard” break level from “20-29” to “30-39”, with the upper level being over 40+ and A* only applicable if the player hit over 12.00 GP and their HB is over 50 for that session For less able players (average ability), change the “standard” break level down from “20-29” to “10-19” with the upper level being over 20+ and an A* only applicable if the player hits over 12.00 GP and their HB is over 30 for that session.

What Level am I?

NB this is the majority of their breaks, NOT their HB. The players should assess their performances over a season and amend the “levels” to match their ability accordingly.
 * In a session, if the majority of the players breaks are usually under 15 then they are classed as a beginner. If between 15-24 then they would be classed as an ‘average’ club player. If 25-34, then a ‘good’ club player. If 35-49, then a ‘very good’ club player. If regularly over 50+, then an ‘excellent’ club player/semi pro.

Continuous Tracking

For a period where the BASE is kept as a constant throughout, this system can be applied session after session and can therefore grade the players accordingly for each session. In addition, a running cumulative total of grade points (which may be + or - over the period) can be accrued and then averaged out to provide an average grade points per session. This can then be graded (at standard level) to measure the player’s overall seasonal performance in comparison to that of the defined BASE used.

Copyright © April 2012 by Ric L. Washer