Goals Against Average is a statistic

Statistic

A statistic is a single measure of some attribute of a sample . It is calculated by applying a function to the values of the items comprising the sample which are known together as a set of data.More formally, statistical theory defines a statistic as a function of a sample where the function...

 used in ice hockey

Ice hockey

Ice hockey, often referred to as hockey, is a team sport played on ice, in which skaters use wooden or composite sticks to shoot a hard rubber puck into their opponent's net. The game is played between two teams of six players each. Five members of each team skate up and down the ice trying to take...

, water polo

Water polo

Water polo is a team water sport. The playing team consists of six field players and one goalkeeper. The winner of the game is the team that scores more goals. Game play involves swimming, treading water , players passing the ball while being defended by opponents, and scoring by throwing into a...

, lacrosse

Lacrosse

Lacrosse is a team sport of Native American origin played using a small rubber ball and a long-handled stick called a crosse or lacrosse stick, mainly played in the United States and Canada. It is a contact sport which requires padding. The head of the lacrosse stick is strung with loose mesh...

, and soccer that is the mean

Mean

In statistics, mean has two related meanings:* the arithmetic mean .* the expected value of a random variable, which is also called the population mean....

 of goals

Goal (ice hockey)

In ice hockey, a goal is scored when the puck completely crosses the goal line between the two goal posts and below the goal crossbar. A goal awards one point to the team attacking the goal scored upon, regardless of which team the player who actually deflected the puck into the goal belongs to...

 allowed per game by a goaltender

Goaltender

In ice hockey, the goaltender is the player who defends his team's goal net by stopping shots of the puck from entering his team's net, thus preventing the opposing team from scoring...

.

For ice hockey, it is calculated per game by dividing the number of goals against multiplied by 60 (or the total amount played per game) by the number of minutes played. For a season, divide the total number of goals against by the result of the total number of minutes played (also known as time on ice) divided by 60. Alternatively, take the number of goals against, multiply that by 60 minutes and then divide by the amount of minutes played. When calculating GAA, overtime goals and time on ice are included, where as empty net and shootout goals are not. It is typically given to two decimal places.

GAA is analogous to a baseball

Baseball

Baseball is a bat-and-ball sport played between two teams of nine players each. The aim is to score runs by hitting a thrown ball with a bat and touching a series of four bases arranged at the corners of a ninety-foot diamond...

 pitcher

Pitcher

In baseball, the pitcher is the player who throwsthe baseball from the pitcher's mound toward the catcher to begin each play, with the goal of retiring a batter, who attempts to either make contact with the pitched ball or draw a walk. In the numbering system used to record defensive plays, the...

's earned run average

Earned run average

In baseball statistics, earned run average is the mean of earned runs given up by a pitcher per nine innings pitched. It is determined by dividing the number of earned runs allowed by the number of innings pitched and multiplying by nine...

 (ERA). In Japanese language, the same translation (防御率) is used for both GAA and ERA, because of this analogy.

The top goaltenders in the National Hockey League

National Hockey League

The National Hockey League is an unincorporated not-for-profit association which operates a major professional ice hockey league of 30 franchised member clubs, of which 7 are currently located in Canada and 23 in the United States...

 currently have a GAA of about 2.00, although the measure of a good GAA changes as different playing styles come and go. The top goaltenders in the National Lacrosse League

National Lacrosse League

The National Lacrosse League is a men's professional indoor lacrosse league in North America. It currently has nine teams; three in Canada and six in the United States. Unlike other lacrosse leagues which play in the summer, the NLL plays its games in the winter and spring. Each year, the playoff...

 however, currently have a GAA of about 10.00, and the top 2005 Western Lacrosse Association

Western Lacrosse Association

The Western Lacrosse Association is an amateur league of men's Senior A box lacrosse sanctioned by the Canadian Lacrosse Association. It consists of seven teams, based in cities throughout southwestern British Columbia. Each year, the playoff teams battle for the right to compete against the...

 goaltenders had a GAA of about 9.00. At their best, elite NCAA water polo goalies have a GAA between 3.00 and 5.00.

Since the statistic is highly dependent on the team playing in front of a goalie, save percentage

Save percentage

Save percentage is an ice hockey and lacrosse statistic that represents the percentage of shots on goal a goaltender stops...

is usually considered a more accurate measure of a goaltender's skill, especially in ice hockey and lacrosse, as it takes into account the number of shots the goaltender has faced. In soccer, since it is considered a part of the goalkeeper's job to coach defenders on proper positioning to prevent opponents' shots, GAA is more commonly used to evaluate goalkeepers than save percentage.