A player’s level is based on two calculations: their initial level and their subsequent match adjustments.
In a nutshell, the algorithm uses:
Maths - at the heart of the algorithm we use the match result (including any score information we have) to calculate the relative level each team played at, we call this the played at ratio. Based on probabilities of winning individual points at different relative levels we have calculated a mapping that converts the match result to each teams played at ratio. I.e. if you’re winning 6-1 in games then you’re playing twice as well as your opponents. 6-2 is 55% better, 6-3 is 33% better, 6-4 is 18% better, 7-5 is 14% better, even down to a 7-6 tie break which works out as 6% better.
Weighting - the more important the match (e.g. a tournament) the greater the weighting. This means that when you play different types of matches your level will be damped accordingly.
Damping - there is a reasonable amount of damping dialled into each match trying to get the balance right between dynamic change and slow progress. The algorithm does its best to reward every player for a good result and, as a consequence, an appropriate level reduction if the result isn't so good. The intention is that a player's level is a reasonable assessment of their current playing level within a match or two. The maths determines what level you should be, the damping determines how long it takes to get there. As we are all human and vary quite a bit from match to match, we need some damping!
Behavioural modelling - not everyone puts 100% effort in every match and that’s down to behaviour. Based on the analysis of millions of results on our system, we’ve built an extensive behavioural model that allows us to predict different scenarios where we need to include additional adjustments.
Initial levels - the initial level of a player determines their starting point in the system, not all players enter the system at the same level. therefore has a big impact on the current level. See our Understanding Initial levels FAQ for more details.
Partner ratios - partners aren’t always the same level and we need to reflect that as we interchange between team and individual levels. If the same two players play together continuously, unless someone sets their level manually, the system doesn’t know how the partners compare to each other as it has nothing to go on. As soon as people play with multiple partners we are able to understand the level of each individual. See our Player partner-ratios in initial level setting FAQ for more details.