How Our Models Work
We publish ratings, win probabilities and season simulations for AFL, football (soccer) and tennis. Every number on the site comes from a model we wrote and can explain. These pages describe each one in plain words: what it measures, how it is built, where you can see it, and where it is likely to be wrong.
The code is open source. The AFL models live in torp and the football models in panna.
AFL player ratings: TORP
TORP is our headline AFL player rating. It is a 50/50 blend of two parts: EPR, which credits a player for the scoreboard value of what he did with the ball, and PSR, which predicts his effect on the match margin from his statistical profile. The page explains both parts, how recent games are weighted, and how a player’s rating is pulled toward average when we have seen little of him.
AFL expected possession value
AFL expected possession value covers the per-game side: how we put a points value on where the ball is, how the change in that value is shared between the player who disposes of the ball and the player who receives it, and how that becomes the value measures shown on match and player pages.
Football player and team ratings
Football ratings explains Panna, our plus-minus rating built from who was on the pitch for every stretch of every match, and the composite ratings built on top of it: Piero for players and Tiento for teams. It also covers the PSR, SPMR and EPR components.
Football possession value and expected goals
Football possession value and expected goals explains EPV, our measure of how close a team is to scoring the next goal from any position on the pitch, along with the shot models xG and xGOT and the win probability added measure.
Season and tournament simulations
Simulations explains how we turn match forecasts into odds: the AFL ladder and finals simulator, the football league title and relegation simulations, the World Cup simulator and the tennis Grand Slam draw simulator.
Stat glossaries
For what each column on the site means, see the AFL stat definitions and the football stat definitions.