Ratings Central Guidelines for TTSA Affiliated Clubs & Event Directors

These guidelines are to be used by SA Event Directors when setting the initial prior for a player new to Ratings Central.  The initial prior is a term meaning the beginning player rating.
Both Table Tennis Australia (TTA) and Table Tennis South Australia (TTSA) has adopted the the Ratings Central system, which is a fully automated player rating system. The system is used in many countries throughout the world.  TTSA provide the results of all sanctioned tournaments, state championships, the country carnival and the TTSA Winter Pennant results to Ratings Central.

What is an Event Director

A person may apply to Ratings Central for permission to submit resuts to the Ratings Central website usually via software such as "Zermelo" and "Cantor" downloaded from the Ratings Central website (Note - The Southern Association use "CATTS").  That person once authorised is refered to by Ratings Central as an 'Event Director'. Prior to applying a person must complete a short course about "Ratings Central" in "Spin Accademy" - Click on the following link for more information: How to become a Ratings Central Event Director 
TTSA encourages affiliates to submit the results of their pennant competitions and tournaments to Ratings Central. Ratings Central only allows submission of singles events. Ratings Central does not permit the submission of handicapped events.
An event to be submitted to Ratings Central must be a a planned and serious event such as a tournament or a pennant competition, 

Rating Points

Each players skill level is described by a rating with mean and standard (plus/minus) deviation e.g. 1250 (+/-50)
Players gain points for singles matches they win and lose points for matches they lose. The mean and standard deviation is recalculated according to the rating of the opponent or the skill difference between the two competitors in each match. The player rating is recalculated automatically after each event when matches are submitted to Ratings Central for processing

New Players

From the 1st January 2021 all Event Directors are to assign interim priors for new players according to the ratings bands shown below.  These bands have been agreed upon between TTSA & TTA. The final rating will be calculated by Ratings Central once the tournament (or pennant) results are submitted and processed.

Ratings Bands

The following ratings bands are based upon the TTSA Winter Pennant Competition by determining the mean of the Ratings Central rating of the players who play in the different divisions.
From the 1st Januray 2021 only the ratings shown below may be applied for a new player to Ratings Central.  Also, please note that the minimum rating that may be applied is 800 +/- 150. (Note - This also applies to new juniors)
Should the initial ratings be set for a value other than shown below then you will be asked to make a correction and re-submit your tournament or pennant competition to Ratings Central.

Minimum Initial Prior - The 500 Floor Rule

This means that the ‘floor’ as a result of the players initial mean minus 2 standard deviations must be greater than or equal to 500. By following the bands shown above, you will always satisfy this rule. i.e. the floor of lowest band of 800 (+/- 150) is 500 as 800 − 2 × 150 = 500. 

Former Method of Setting the Initial Prior

Previously Event Directors would assign an initial prior based upon their assessment of the new players playing strength in comparison to players that they knew.  This was a very subjective method and was not always accurate.  
When David  Marcus first developed the Ratings Central system, he very quickly realized everyone had differing approaches as to 'who is what standard' and thus has recently advocated a 'large standard deviation' approach to allow results to settle down over time - reducing efforts in judgments and putting more faith into the system.