Win_probability
Win probability is a statistical tool which suggests a sports team's chances of winning at any given point in a game, based on the performance of historical teams in the same situation.[1] The art of estimating win probability involves choosing which pieces of context matter. Baseball win probability estimates often include whether a team is home or away, inning, number of outs, which bases are occupied, and the score difference. Because baseball proceeds batter by batter, each new batter introduces a discrete state. There are a limited number of possible states, and so baseball win probability tools usually have enough data to make an informed estimate.
American football win probability estimates often include whether a team is home or away, the down and distance, score difference, time remaining, and field position. American football has many more possible states than baseball with far fewer games, so football estimates have a greater margin of error. The first win probability analysis was done in 1971 by Robert E. Machol and former NFL quarterback Virgil Carter.
As a brief example, guessing that each team playing at home will win is based on home advantage. This guess uses a single contextual factor and involves a very large number of games. But with only one factor, the accuracy of this guess is limited to home advantage itself (about 55–70% across sports) and does not change within the game based on in-game factors.
Win probability added is the change in win probability, often how a play or team member affected the probable outcome of the game.[2]