Possession in soccer as well as many other sports is indicated by the overall amount of time a team spends with the ball in its own possession. As a result, a statistics keeper is often required to keep track of how long each team has possession of the ball during a game. Often, the team with the greater time of possession comes out victorious, due to the longer amount of time it gets to spend attacking the defense.
Time of Possession
Time of possession is defined in soccer as the total amount of time a team possesses a ball while on offense. The calculation of this number depends directly on the level of soccer and statistics keeping that goes into each game. For a recreational league game, time of possession may not even be calculated during the game. For higher level games, a manual clock will be placed next to the scoreboard that a scorekeeper will hit each time the ball changes possession. In professional soccer, an automated calculation is put in place to increase precision and accuracy.
For intermediate-level soccer games, possession is often calculated using a manual clock. During the game, the individual who is in charge of the game clock will also have a chess-style clock in front of him with two dials and a button above each dial. Once he sees the ball change possession, he will hit the button above the dial of the corresponding team, hitting between each dial during every change of possession. While this calculation will keep a fairly accurate time of possession, it is subject to human error, which is why it is not often used in professional matches.
In high-level soccer matches, time of possession is tabulated through an automated calculation that is based directly on the number of passes each team executes over the course of one game. Each pass is calculated and plugged directly into this equation. The total number of passes are then divided by the total number of passes in the game to get a percentage for the total. While this is not directly a time calculation, it ends up directly correlating to a team's time of possession during a game.
Change of Possession
Change of possession occurs in a soccer match when the ball is stolen by an opponent or the ball goes out of bounds, giving the ball to the other opponent. A change of possession is always performed in accordance with the official rules of the game. Despite this, the referees who enforce the game are prone to human error, resulting in missed calls and change of possession calls when they should not have occurred.