Methods
Brier Score
A measure of probability forecasts: the average squared gap between the forecast and what happened (1 if it happened, 0 if not). Lower is better; always saying 50% scores 0.25.
How we use it
We report the Brier score of our home-team win probability on every completed game, by season. A forecaster who says 70% and is right scores 0.09 on that game; one who says 70% and is wrong scores 0.49. Bold forecasts are rewarded only if they are right often enough.
Where to see it
Related terms
- Calibration
- Whether forecast probabilities match how often things happen: of all the teams given a 70% chance, about 70% should win.
- Win Probability
- The model's estimated chance that a team wins a game, from the share of simulated games it wins. A 70% favorite should still lose about 3 games in 10.