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NBA win probability, explained.
What the numbers mean, how they are graded, and how the well-known ones hold up. Every figure on these pages comes from the data and is rebuilt every day.
What is NBA win probability?
What an NBA win probability means, how to read 55% or 75%, where the number comes from, and how to tell a good one from a bad one.
Calibration and the Brier score, explained
How to grade a forecaster: calibration (does 70% happen 70% of the time?) and the Brier score, with real NBA calls scored one game at a time.
How accurate is ESPN BPI?
ESPN BPI picked the winner in about 69% of NBA games. We graded its probabilities on 2,631 games beside the market, Clutch and the home team.
How to check a prediction was made before the game
Anyone can say they called it after the final. Three marks of a real pregame prediction, shown on a real night of sealed NBA numbers.