Sabermetrics is the specialized analysis of baseball through objective evidence, especially baseball statistics that measure in-game activity. The term is derived from the acronym SABR, which stands for the Society for American Baseball Research. It was coined by Bill James, who is one of its pioneers and is often considered its most prominent advocate and public face.
General principles 
The Sabermetric Manifesto by David Grabiner (1994) begins:
Bill James defined sabermetrics as "the search for objective knowledge about baseball." Thus, sabermetrics attempts to answer objective questions about baseball, such as "which player on the Red Sox contributed the most to the team's offense?" or "How many home runs will Ken Griffey hit next year?" It cannot deal with the subjective judgments which are also important to the game, such as "Who is your favorite player?" or "That was a great game."
It may, however, attempt to settle questions such as "Was Willie Mays faster than Mickey Mantle?" by establishing several possible parameters for examining speed in objective studies (how many triples each man hit, how many bases each man stole, how many times he was caught stealing) and then reaching a tentative conclusion on the basis of these individual studies.
Sabermetricians frequently question traditional measures of baseball skill. For instance, they doubt that batting average is as useful as conventional wisdom says it is because team batting average provides a relatively poor fit for team runs scored. Sabermetric reasoning would say that runs win ballgames, and that a good measure of a player's worth is his ability to help his team score more runs than the opposing team. This may imply that the traditional RBI (runs batted in) is an effective metric; however, sabermetricians also reject RBI, for a number of reasons. Rather, sabermetric measures are usually phrased in terms of either runs or team wins. For example, a player might be described as being worth 54 offensive runs more than a replacement-level player at the same position over the course of a full season, as the sabermetric statistic VORP can indicate.
Sabermetrics is concerned both with determining the value of a player or team in current or past seasons and with attempting to predict the value of a player or team in the future. Many areas of study are still in development, specifically in the area of performance measurement.
Early history 
Sabermetrics research began in the middle of the 20th century. Earnshaw Cook was one of the earliest researchers of sabermetrics. Cook gathered the majority of his research in his 1964 book, Percentage Baseball. The book was the first of its kind to gain national media attention, although it was widely criticized and not accepted by most baseball organizations.
- Base runs (BsR)
- Batting average on balls in play (BABIP)
- Defense independent pitching statistics (DIPS)
- Defensive Runs Saved (DRS)
- Equivalent average (EQA)
- Fantasy batter value (FBV)
- Late-inning pressure situations (LIPS)
- On-base plus slugging (OPS)
- PECOTA (Player empirical comparison and optimization test algorithm)
- Peripheral ERA (PERA)
- Pythagorean expectation
- Range factor
- Runs created
- Secondary average
- Similarity score
- Speed Score
- Super linear weights
- Total player rating, or Batter-Fielder Wins (TPR, BFW); Total Pitcher Index, or Pitcher Wins (TPI, PW)
- Ultimate zone rating (UZR)
- Value over replacement player (VORP)
- Win shares
- Wins above replacement (WAR)
Notable proponents 
- Russ Brandon: Team President and CEO of the Buffalo Bills is going to incorporate Sabermetrics to contracts, and use in conjunction with scouting and player analysis beginning in 2013.
- Sandy Alderson: Former General Manager of the Oakland Athletics, Alderson began focusing on sabermetric principles toward obtaining relatively undervalued players in 1995. He became GM of the New York Mets in late 2010.
- Billy Beane: Athletics' General Manager since 1997. Although not a public proponent of sabermetrics, it has been widely noted that Beane has steered the team during his tenure according to sabermetric principles. In 2003, Michael Lewis published Moneyball about Billy Beane's use of a more quantitative approach. In 2011, a film based on Lewis' book which dramatised Beane's use of sabermetrics was released, starring Brad Pitt in the role of Beane.
- Carson Cistulli: Senior editor of FanGraphs, member of the BBWAA
- Earnshaw Cook: Early researcher and proponent of statistical baseball research. His 1964 book Percentage Baseball was the first book of baseball statistics studies to gain national media attention.
- Paul DePodesta: A key figure in Michael Lewis' book Moneyball: The Art of Winning an Unfair Game as Beane's assistant in Oakland.
- Theo Epstein: President of Baseball Operations for the Chicago Cubs. As GM of the Red Sox, Epstein hired sabermetrician Bill James.
- Bill James: Widely considered the father of sabermetrics due to his extensive series of books, although a number of less well known SABR researchers in the early 1970s provided a foundation for his work. He began publishing his Baseball Abstracts in 1977 to study some questions about baseball he found interesting, and their eclectic mix of essays based on new kinds of statistics soon became popular with a generation of thinking baseball fans. He discontinued the Abstracts after the 1988 edition, but continued to be active in the field. His two Historical Baseball Abstract editions and Win Shares book have continued to advance the field of sabermetrics, 25 years after he began. In 2002 James was hired as a special advisor to the Boston Red Sox.
- Christina Kahrl: Co-founder of Baseball Prospectus and current ESPN columnist, Kahrl puts an emphasis on advanced baseball analytics.
- Sean Lahman: Created a database of baseball statistics from existing sources and in the mid-1990s made it available for free download on the Internet, providing access to statistical data in electronic form for the first time.
- Voros McCracken: Developed a system called Defense Independent Pitching Statistics (DIPS) to evaluate a pitcher based purely on his ability.
- Rob Neyer: Senior writer at ESPN.com and national baseball editor of SBNation and former assistant to Bill James, he has worked to popularize sabermetrics since the mid-1980s. Neyer has authored or co-authored several books about baseball, and his journalistic writing focuses on sabermetric methods for looking at baseball players' and teams' performance.
- Joe Posnanski: A popular baseball writer and a proponent of sabermetrics.
- Nate Silver: Writer and former managing partner of Baseball Prospectus, inventor of PECOTA. Later applied sabermetric statistical models to the study of politics, particularly elections, and published the results on his blog FiveThirtyEight (later affiliated with The New York Times).
- David Smith: Founded Retrosheet in 1989, with the objective of computerizing the box score of every major league baseball game ever played, in order to more accurately collect and compare the statistics of the game.
- Tom Tango: Runs the Tango on Baseball sabermetrics website. In particular, he has worked in the area of defense independent pitching statistics.
- Eric Walker: Former aerospace engineer turned baseball writer, who played an important part in the early acceptance of sabermetrics within the Oakland Athletics organization. GM Sandy Alderson hired Walker in order to get "some Bill James-like stuff that was proprietary to us."
- Keith Woolner: Creator of VORP, or Value over Replacement Player, is a former writer for sabermetric group/website Baseball Prospectus. He was hired in 2007 by the Cleveland Indians as their Manager of Baseball Research & Analytics.
- Craig R. Wright: A statistician for the Texas Rangers, was the first front office employee in Major League Baseball to work under the title "Sabermetrician."
- Baseball Prospectus is an annual publication and web site produced by a group of sabermetricians who originally met over the Internet. Several Baseball Prospectus authors have invented or improved upon widely relied upon sabermetric measures and techniques. The website publishes analytical articles as well as advanced statistics and projections for individuals and teams. This group also publishes other books that use and seek to popularize sabermetric techniques, including Baseball Between the Numbers and It Ain't Over 'til It's Over.
- The Hardball Times is a website as well as an annual volume that evaluates the preceding major league season and presents original research articles on various sabermetric topics. The website also publishes original research on baseball.
- FanGraphs is a website that publishes advanced baseball statistics as well as graphics that evaluate and track the performance of players and teams. The site also favors the analysis of play-by-play data and PITCHf/x. It draws on some of the advanced baseball metrics developed by well-known sabermetricians such as Tom Tango and Mitchel Lichtman.
- Beyond the Boxscore is a part of SB Nation and specializes in sabermetric analysis and research. It has also launched the careers of many successful sabermetricians.
- SABR is the Society for American Baseball Research, founded in 1971, and the root of the term sabermetrics. Statistical study, however, is only a small component of SABR members' research, which also focuses on diverse issues including ballparks, the Negro Leagues, rules changes, and the desegregation of baseball as a mirror of American culture.
- Fielding Bible Awards are voted on by a panel of sabermetically inclined writers to recognize the best defensive player for each fielding position. It provides an alternative to the Gold Glove Awards, the traditional measurement of fielding excellence.
- Baseball Think Factory is a web forum that includes extensive coverage of and commentary on baseball, usually from the perspective of sabermetrics.
Popular culture 
- Moneyball, the 2011 film about Billy Beane's use of sabermetrics to build the Oakland Athletics. The film is based on Michael Lewis' book of the same name.
- The season 3 Numb3rs episode "Hardball" focuses on sabermetrics, and the season 1 episode "Sacrifice" also covers the subject.
- "MoneyBART", the third episode of The Simpsons' 22nd season, in which Lisa utilizes sabermetrics to coach Bart's Little League Baseball team.
See also 
- Fielding Bible Award
- Win Shares by Bill James
- Whatever Happened to the Hall of Fame? by Bill James
- Total Baseball by John Thorn and Pete Palmer
- The Bill James Historical Baseball Abstract
- Moneyball, by Michael Lewis
- APBRmetrics, the basketball equivalent
- Lewis, Michael M. (2003). Moneyball: The Art of Winning an Unfair Game. New York: W. W. Norton. ISBN 0-393-05765-8.
- Grabiner, David J. "The Sabermetric Manifesto". The Baseball Archive.
- Jarvis, J. (2003-09-29). "A Survey of Baseball Player Performance Evaluation Measures". Retrieved 2007-11-02.
- Albert, James; Jay M. Bennett (2001). Curve Ball: Baseball, Statistics, and the Role of Chance in the Game. Springer. pp. 170–171. ISBN 0-387-98816-5.
- Kipen, D. (June 1, 2003). "Billy Beane's brand-new ballgame". San Francisco Chronicle. Retrieved November 2, 2007.
- Neyer, Rob (November 5, 2002). "Red Sox hire James in advisory capacity". ESPN.com. Retrieved March 7, 2009.
- Shanahan, M. (May 23, 2005). Retrieved November 2, 2007 His numbers are in the ballpark The Boston Globe
- "Bill James, Beyond Baseball". Think Tank with Ben Wattenberg. PBS. June 28, 2005. Retrieved November 2, 2007.
- Ackman, D. (May 20, 2007). "Sultan of Stats". The Wall Street Journal. Retrieved November 2, 2007.
- Jaffe, C. (October 22, 2007). "Rob Neyer Interview". The Hardball Times. Retrieved November 2, 2007.
- Lewis, M. Moneyball. pp. 58–63.
- "Baseball Prospectus". Retrieved 2012-03-04.
- Baseball Between the Numbers. 2006. ISBN 0-465-00596-9.
- Goldman, Steven (2007). It Ain't Over 'til It's Over. ISBN 0-465-00285-4.