Elo is a rating system commonly used in competitive gaming, including Warhammer 40,000, to measure and compare the skill levels of players. It provides a numerical representation of a player's relative strength based on their performance in matches against other players. Here's how Elo works in the competitive Warhammer 40,000 setting:
Starting Rating: Every player begins with an initial Elo rating, often referred to as the "baseline" or "average" rating, which can vary depending on the tournament or competitive league. For Stat Check’s system, it is set at 1500 points.
Match Outcome: When two players with compete against each other in a tournament game, the outcome of the match affects their Elo ratings. If a lower-rated player defeats a higher-rated player, they will earn more Elo points, reflecting their achievement. Conversely, if a higher-rated player wins, they will gain fewer Elo points because they were expected to win based on their higher rating.
Expected Outcome: Elo calculations are based on the expected outcome of a match. Before the game begins, the Elo system predicts the probability of each player winning based on their current ratings. The more significant the rating difference, the more heavily favoured the higher-rated player is. If the lower-rated player wins, it's considered an upset, and they gain more Elo points.
Point Adjustments: After the match, the Elo ratings of both players are adjusted. The amount of points gained or lost depends on the difference in their pre-match ratings, the outcome of the game, and a predetermined constant known as the "K-factor." The K-factor represents the system's sensitivity to rating changes; higher values result in more significant rating swings, while lower values lead to more gradual changes. Stat Check’s system uses a K-factor of 32 for all matches.
Decay - as of January 2024, the Stat Check team has implemented decay to Elo rankings. After a 13 week period of inactivity, a player’s Elo will begin to degrade towards the starting rating of 1500. For every 13 weeks of inactivity, a player’s Elo will be moved by 20% of the difference between their current ranking and the starting ranking. For example, if a player currently has a ranking of 2000, then after 13 weeks of no GT+ activity, their new Elo will be 1900. This was implemented following testing that showed better correlation between Elo ratings and game outcomes with this system in place. (This was initially set at 12 weeks, but revised to be a more “normal” quarterly 13 weeks)
Games played as well as player ranking dates back to February 7 2022. Changes are calculated every week or so.
Last updated 10 December 2024.