Goals Against Average is a statistic used in water polo (as well as ice hockey, field hockey, lacrosse, soccer (football) and other sports with a goalie) that is used to put a goalie’s number of goals allowed into perspective with their total playing time.
It is intended to give a measure of how many goals the goalie allows per unit of regulation game time.
It is considered one statics among some other ones, including win/loss ratio and save percentage that are used to help measure a goalie’s capability.
In Water Polo, goals against average (GAA) calculates as follows:
Goals Against Average = (goals against x game length) / minutes played.
If a goalie has been in net for 637 minutes, has allowed 32 goals in that time, and regulation time for the league they play in is 60 minutes per game:
32 goals against times 60-minute game length is 1,920.
1,920 divided by 637 minutes played is 3.01
Therefore, the goalie’s Goals Against Average (GAA) is 3.01
What counts as a “Goal Against”?
In water polo, a “goal against” is a goal that occurs while the goalie is assigned the position of the goalkeeper.
If the goalie is not on the field of play at the time when the goal happens, a goal against the team does not count against the goalie’s GAA.
Rules for what qualifies as a goal can be found in the Fina rulebook under the method of scoring (other leagues with alternative rules may have different scoring regulations).
What counts as a “Minute Played”?
Each minute that the goalie is an active player in a game counts as a “minute played.”
What is “Game Length”?
Game length varies depending on the league.
Olympic and FINA level water polo games have a game length of 32 minutes (4 periods of 8 minutes), while NCAA games have a length of 28 minutes. Other leagues exist with game lengths of 24 and 36 minutes.