Win probability
CFBD publishes three separate win probability concepts: pregame, in-game, and postgame. Each answers a different question and should be interpreted on its own terms.
All win probabilities are returned as decimals from 0 to 1. They represent
uncertainty, not certainty. A team with a 0.75 probability is expected to win
about three out of four comparable situations over a large sample; it can
still lose the individual game.
Pregame win probability
Pregame win probability estimates the home team's chance of winning before kickoff. It is derived from the available point spread and the historical relationship between spreads and game outcomes.
This is a market-based estimate rather than a CFBD team-rating forecast. Games without a usable spread may not have a pregame probability.
Use the
pregame win probability operation
to retrieve the spread and homeWinProbability together.
In-game win probability
In-game win probability estimates the home team's chance of winning after each play. The current model considers the score, time remaining, down, distance, field position, and possession. Timeout context may also be used where it is available and reliable.
The model introduced for the 2025 season uses separate approaches for three game states:
- Regulation handles the broad range of normal game situations.
- Clutch focuses on late, high-leverage situations where clock and field position behave differently from the rest of the game. Its estimate is blended with the regulation estimate as those situations develop.
- Overtime handles the distinct possession and scoring structure of college overtime.
The model is evaluated for calibration, which asks whether outcomes labeled with a given probability occur at roughly that rate over a large sample. Calibration does not make any one prediction certain.
Stored values for 2025 and later use the revamped model. Values through 2024 remain outputs from the retired models and were not backfilled. Analyses that span that boundary should account for the methodology change, especially when comparing Excitement Index values.
Use the in-game win probability operation to retrieve the play-by-play home-team probability. The final record resolves to the game outcome.
Postgame win probability
Postgame win probability asks how often a team would be expected to win with a similar underlying game performance. It uses aggregate efficiency and game profile measures rather than replaying the in-game probability path.
This is sometimes useful for identifying games where the final result and the underlying performance tell different stories. It is not a replacement for the score, and it is not the final value from the in-game model.
Postgame win probability appears in advanced game and team box score data.
Excitement Index
Excitement Index summarizes the movement in win probability over a game. Larger and more frequent swings produce a higher value. It describes the path of the game, not team quality or the closeness of the final score by itself.
Because the measure is derived from in-game win probability, the 2025 model change also affects Excitement Index comparability across the 2024-2025 boundary.
Further reading
The underlying models are proprietary. These resources explain the design and interpretation without publishing fitted parameters, model artifacts, or the complete production calculation.