Rating System

Let's start with the basics and why we believe Arm Ratings is the most accurate Arm Wrestling Rating System in the world.  Firstly, there are no "Expert Opinions" or any type of human determined variables that vary from competitor to competitor whatsoever in this formula or the end ratings.  This is a purely mathematical calculation based on match results that apply identically and equally to every competitor.  Arm Ratings is based on an improved Elo rating system catered specifically to Arm Wrestling that combines elements from standard Elo, Glicko, and custom deviations based on activity and match history only.  Current ratings are derived from results of matches from every format, including tournament and supermatch.  This way, no matter how the competition meta shifts, or how a competitor chooses to compete, the ratings will reflect the entirety of the sport's match results.

Here are the seven factors used to determine the ratings:

1.  Glicko - Arm Ratings uses the Glicko Rating System.  In comparison to ELO, which is already considered reliable regardless of a competitor's inactivity, match results, or strength of opponents, the Glicko system introduces a new value associated with each competitor called ‘Rating Deviation’ which measures the reliability of a competitor's rating.  It provides an indication of a competitor's expected performance with 95% confidence within the interval [R-2xRD, R+2xRD].  Rating Deviation increases due to inactivity and decreases after match results are submitted.  It is responsible for the gravity of a result when the opponent’s rating change is calculated.  It also determines the development coefficient of a competitor's rating.  With the Glicko Rating System, if a competitor competes against a stronger competitor and wins, their ranking goes up significantly.  If they compete against a weaker competitor and win, the ranking goes up only a little.

2.  Round Calculations - Win/Loss calculations take place every ROUND of a match.  This allows for a much more accurate rating, as more data truly shows the difference in strength between competitors.

3.  Timeline - Arm Ratings was started in 2023, and calculations are based on all official match data since 2018.  An initial 5 year data source was needed to achieve an accurate rating system since some competitor's may only compete once a year.

4.  Initial Rating -  Competitors earn an initial rating by winning a match against a rated opponent AND completing three rounds against rated opponents.  When an unrated competitor defeats a rated opponent, they will have their initial rating set to that of their opponent's pre-match rating (maximum 1980) and then calculated based on the results of that match, after three rounds are completed against rated opponents.  If an unrated competitor defeats a rated competitor in a single one-round match (as in a tournament format) but do not complete the requirements to become rated, the rated opponent will not lose any rating.  This will prevent a potential skew in the ratings due to foul or coincidental losses.  The only exception to this rule is the consensus top competitors of 2018, who started with a rating of 2000 to initiate the rating system.

5.  +3 Rule -  A competitor may not exceed a three-round advantage in victory calculations against a rated opponent in any given match.  For instance, a 6-0 win by a competitor will only have the first 3 rounds calculated whereas a 4-2, 4-1, or 3-0 victory would be calculated normally.  This prevents overcalculation that can reduce accuracy by inflating or deflating ratings inorganically and due to the varying styles and lengths of matches across promotions and events.

6.  Withdrawal - If a competitor withdraws from a confirmed match for any reason (injury, illness, choice, etc.), their rating will be calculated as a loss of each round of the confirmed match.  Their scheduled opponent will not reflect this as a victory and will have no rating change.

7.  Decay - After a competitor reaches two years of inactivity, which is classified as not competing against another rated opponent OR being calculated a loss due to withdrawal, they will be removed from the ratings and be reclassified as an unrated competitor.  This calculation factor took effect on launch (5-29-23) but was not part of the initial rankings due to the COVID years.

8.  Fair Match Ratings - A competitor cannot gain rating against an unrated opponent or an opponent with a rating 100+ lower than their own unless the lower competitor has at least 2000 rating at the beginning of the match and vice versa.

Information

A brief comparison guide between the ELO and the Glicko rating systems