Basketball Statistics Glossary

Here is a list of some of the statistics I use most often for your (and my) reference. It’s helpful to me so I thought I’d share.

Each entry has the following:

Name of the metric
A description of what it’s used for
The question it answers
A more technical definition
The formula itself
A link to a description from someone more intelligent than I

Please add any corrections, questions, or suggestions in the comments section.

Assist ratio: Used most often for point guards, assist ratio can be considered a proxy for passer decision making or a means to understanding the degree to which a player facilitates scoring opportunities for others. How often does a player create an assist? The formula is an opportunity rate that describes the percentage of plays on which a player creates assist. Ast/(Ast + (FGA + .44*FTA + TO)). Read more >>>

Assisted field goal percentage: Used primarily for teams, assisted field goal percentage tells us how often a team’s scoring opportunities were facilitated by a pass. What percentage of shots were created by an assist? The formula describes the number of assists per field goals attempted to give us the percentage of assisted shots out of all shots taken. A/FGA. Read more >>>

Boxscores: Used for all players, Boxscores tell us how much an individual contributes to team wins. What portion of team wins can be attributed to a given player? The formula describes a player’s valuable contributions to the team in terms of team wins. Click for the formula and to read more >>>

Defensive contribution: Used to very roughly approximate a player’s contribution to her team’s defensive quality, on the assumption that players who play more minutes on a good defensive team deserve credit as quality defenders. How much does a player contribute to the quality of her team’s defense? The formula describes a player’s contribution to helping a team play defense above or below average in terms of their percentage of team minutes played. (Mins/TM Mins)*Tm Defensive Rating.

Defensive plus/minus: Used to measure a player’s defensive impact in terms of the difference between points scored when they are on the court and off the court (therefore positive numbers indicate a positive defensive impact). How much does a player influence the opponents’ ability to score? The formula describes the number of opponents’ points scored per one hundred possessions when a player is on the court vs. off the court.

Defensive value: Used to approximate a player’s defensive value to her team based upon blocks, defensive rebounds, steals, and personal fouls. How valuable is a player to her team defensively? The formula describes the value of a player’s defensive contributions per 40 minutes.
((dreb * .511 + stls * 1.60 + blks * .98 + pf * -.22)/minutes) * 40. Read more >>>

Diamond Rating: Used to approximate a player’s capacity to increase their statistical production if they played more often. How much more would a player produce if she got more minutes? The formula describes the difference between a player’s current production and expected production given their current minutes played and estimates their level of production with increased minutes. R*40 - R*Min/G + (R - leagueR)*40. Read more >>>

Effective field goal %: Used to measure a player’s shooting ability in terms of field goals and free throws. How well does a player shoot when taking free throw shooting into account? The formula describes the percentage of field goals and free throws made per field goal attempt. eFG% = (FGM + .5*3PM)/FGA. Read more >>>

Free throw rate: Used to measure the how many free throws a team (or player makes) for every field goal attempted. How often does a team score from the free throw line? The formula describes the percentage of free throws made per field goal attempted. FTM/FGA. Read more >>>

Net Plus/Minus: Used to describe a player’s net impact on the game’s score. How does a player's presence impact the game score? Read more >>>

Offensive rebounding rate: Used to measure how well a team gets available offensive rebounds. How often does a team get an offensive rebound? The formula is an opportunity rate that describes a team’s offensive rebounds per total rebounds available as calculated by their offensive rebounds and the opponent’s defensive rebounds. Team OReb% = TmOReb / (TmOReb + OppDReb) Read more >>>

Points/zero point possession: Used for individual players, points per zero point possession could be considered as a proxy for scorer decision making or a means to understand how efficiently a player manages scoring opportunities. How often is a player individually responsible for scoring possessions and non-scoring possessions? The formula describes the number of points a player scores per missed field goals, missed free throws, and turnovers. Pts/(FGx*.693 + FTx/2*.693 + to).

Pure point rating: Used mostly for point guards, pure point rating can be used as a proxy for point guard quality by approximating the rate at which a player creates scoring opportunities for others. How well does a player create scoring opportunities per others? The formula describes the net value of scoring opportunities a player created for teammates per minute played. 100*((ast*2/3)-to)/mins (not pace adjusted). Read more >>>

SPI Player Styles Spectrum: Used to describe the type and quality of each player in terms of scoring, perimeter skills, and interior skills. What type of player is she and to what degree does she exemplify that type? The formula describes the degree to which a player is a scorer, perimeter play-maker, or interior play-maker. For the formula and to read more >>>

SPI Versatility: Based upon the player styles spectrum, this looks at how versatile a player is in terms of scoring, perimeter skills, and interior skills. How versatile is a player in terms of playing style? The formula is based upon John Hollinger’s versatility formula which takes the cube root of a player’s points, assists, and rebounds. In this case, the formula takes the cube root of the components of a player’s SPI style multiplied together.

Synergy score: Used to describe the type of offense a team plays in terms of ball movement and individual play. For example, a score of 60-70 is indicative of a team that relies heavily on individual play, a score of 70-75 is a team that balances individual scoring and ball movement, and a score of 75+ is indicative of a team that relies heavily on ball movement to create scoring opportunities. (It’s important to note that while a team’s synergy score is a descriptive statistic, an opponent’s synergy score can explain how well a team disrupted their opponent’s offense.) How well does a team move the ball? The formula simply adds a team’s assisted field goal percentage to their effective field goal percentage to approximate how well they move the ball to create quality scoring opportunities. A/fga+eFG%. Read more >>>

Team Dynamics rating: Describes how well a team executes the fundamental aspects of basketball: ball movement, managing possessions, and making free throws. Offensive dynamics describe a team’s performance, whereas defensive dynamics describe the opponent’s performance. (It’s important to note that there is no magic formula to win – different teams will balance the elements of team dynamics depending on personnel and match-ups.) How well does a team move the ball, manage possessions, and make free throws? The formula adds together synergy, offensive rebounding rate, turnover rate, and free throw rate to arrive at a team’s score. With a few exceptions, the team with the higher score will win the game. Read more >>>

True shooting percentage: Used for players or teams, true shooting percentage describes a team’s field goal, three point, and free throw shooting. How well does a team shoot when taking free throw shooting and three-point shooting into account? The formula is a ratio of points scored per total field goal attempts and free throw attempts, thus accounting for the additional points scored on three pointers. TS% = Pts/(2*(FGA + (.44*FTA))). Read more >>>

Turnover rate: Used for players or teams, turnover rate describes how often a player(s) turn the ball over. How often does a possession end with a turnover? The formula describes the number of turnovers per possession for a team or player. TO/(FGA - OR + TO + 0.4 * FTA). Read more >>>

Usage percentage: Used to describe how often a player tries to create a play for their team – scoring or turning the ball over -- while on the court. The theory goes that having the ball in position to create any type of play is indicative of either ball dominance or a team’s faith in a player’s ability…which is why it is best used with some indicator of efficiency. How often is a player involved in making a play for their team? The formula describes the percentage of a team’s plays that a player is individually responsible for while on the court. For the formula and to read more >>>

Valuable Contributions Ratio: Valuable contributions rating provides us with an idea of an individual player’s ability to make contributions to the team, independent of team success. How much does a player contribute when she is on the floor? It’s a ratio of player production to team production and he describes the basis for the “production” aspect of this statistic at Hardwood Paroxysm.

Relevant Links

Basketball-Reference.com glossary
http://www.basketball-reference.com/about/glossary.html

Storm Statistical Analysis Primer
http://www.wnba.com/storm/news/stats101.html