Estimating Possessions


In order to predict the outcome of a game, we need to estimate the number of points that each team will end up with at the end of each possession.

The first step is to understand the 3 outcomes for a team that has the ball.

There are only three things that can happen when the team has the ball in a normal possession: 1. They score a two or three point field goal 2. They score a one point free throw. 3. There's a turnover and the other team ends up with the ball.

There are also times when a team will shoot freethrows without it counting as a possession.

The Possessions Equation

A common equation for possessions is as follows:

poss = 0.96 * (FGA - ORB + TOV + (0.44 * FTA))

Where 0.96 adjusts for team rebounds and 0.44 is an adjustment for free throws that don't count as possessions.

Basketball-reference.com provides us with a more robust equation to estimate possessions:

poss = 0.5 * ((teamFGA + 0.4 * teamFTA - 1.07 * (teamORB / (teamORB + oppDRB)) * (teamFGA - teamFGM) + teamTOV) + (oppFGA + 0.4 * oppFTA - 1.07 * (oppORB / (oppORB + teamDRB)) * (oppFGA - oppFG) + oppTOV))

Spurs: 97.7 for first formula

Predicting a Team's Score

(342)+(113)+20 spurs 121