Jeff Sagarin
Encyclopedia
Jeff Sagarin is an American
sports statistic
ian well-known for his development of a methodology for ranking and rating sports teams in a variety of sports. His ratings have been a regular feature in the USA Today
sports section since 1985, have been used by the NCAA
Tournament Selection Committee to help determine the participants in the NCAA Men's Division I Basketball Championship
tournament since 1984, and have been a part of the Bowl Championship Series
since its inception in 1998.
in mathematics
from the Massachusetts Institute of Technology
in 1970. He grew up outside of New York City
in Westchester County in New Rochelle, New York
. He moved to Bloomington, Indiana
, where he currently lives, in 1977.
s, does not divulge the exact methodology behind his system. He offers two rating systems, each of which gives each team a certain number of points. One system, "Elo chess," is presumably based on the Elo rating system
used internationally to rank chess players. This system uses only wins and losses, with no reference to the victory margin. The other system, "Predictor," takes victory margin into account. For that system, the difference in two teams' rating scores is meant to predict the margin of victory for the stronger team at a neutral venue. For both systems, teams gain higher ratings within the Sagarin system by winning games against stronger opponents, factoring in such things as home-venue advantage. For the Predictor system, margin of victory (or defeat) factors in also, but a law of diminishing returns
is applied. Therefore, a football
team that wins a game by a margin of 7-6 is rewarded less than a team that defeats the same opponent under the same circumstances 21-7, but a team that wins a game by a margin of 35-0 receives similar ratings to a team that defeats the same opponent 70-0. This characteristic has the effect of recognizing "comfortable" victories, while limiting the reward for running up the score.
At the beginning of a season, when only a few games have been played, a Bayesian network
weighted by starting rankings is used as long as there are whole groups of teams that have not played one another, but once the graph
is well-connected, the weights are no longer needed. Sagarin claims that from that point, the rankings are unbiased. http://www.usatoday.com/sports/sagarin/bkt0809.htm
college football
and basketball
, where, with hundreds of teams in NCAA Division I competition, there is no way a team can play against more than a small fraction of its competitors. Therefore, in determining the participants in championship games and tournaments, it is necessary to distinguish between teams that have compiled impressive win-loss records against strong competition and teams that have defeated weaker opponents.
In addition, sports rating systems are generally of great interest to gamblers. Gamblers use Sagarin's ratings as a source of "Power Rankings," traditionally used as a way to determine the spread between two teams.
However, Sagarin's ratings are being increasingly viewed as antiquated with some speculation that his rankings will no longer be used in upcoming BCS Rankings following this year. This is primarily due to his rankings being viewed as the least reliable and relevant than other computer rankings.
, Sagarin advises the Dallas Mavericks
about which lineups to use during games and which free agents to sign using a system called Winval. Winval is modeled after hockey's plus/minus system. The pair are paid over $100,000 for use of the system.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
sports 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...
ian well-known for his development of a methodology for ranking and rating sports teams in a variety of sports. His ratings have been a regular feature in the USA Today
USA Today
USA Today is a national American daily newspaper published by the Gannett Company. It was founded by Al Neuharth. The newspaper vies with The Wall Street Journal for the position of having the widest circulation of any newspaper in the United States, something it previously held since 2003...
sports section since 1985, have been used by the NCAA
National Collegiate Athletic Association
The National Collegiate Athletic Association is a semi-voluntary association of 1,281 institutions, conferences, organizations and individuals that organizes the athletic programs of many colleges and universities in the United States...
Tournament Selection Committee to help determine the participants in the NCAA Men's Division I Basketball Championship
NCAA Men's Division I Basketball Championship
The NCAA Men's Division I Basketball Championship is a single-elimination tournament held each spring in the United States, featuring 68 college basketball teams, to determine the national championship in the top tier of college basketball...
tournament since 1984, and have been a part of the Bowl Championship Series
Bowl Championship Series
The Bowl Championship Series is a selection system that creates five bowl match-ups involving ten of the top ranked teams in the NCAA Division I Football Bowl Subdivision , including an opportunity for the top two to compete in the BCS National Championship Game.The BCS relies on a combination of...
since its inception in 1998.
Background
Sagarin earned a Bachelor of ScienceBachelor of Science
A Bachelor of Science is an undergraduate academic degree awarded for completed courses that generally last three to five years .-Australia:In Australia, the BSc is a 3 year degree, offered from 1st year on...
in mathematics
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
from the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
in 1970. He grew up outside of New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
in Westchester County in New Rochelle, New York
New Rochelle, New York
New Rochelle is a city in Westchester County, New York, United States, in the southeastern portion of the state.The town was settled by refugee Huguenots in 1688 who were fleeing persecution in France...
. He moved to Bloomington, Indiana
Bloomington, Indiana
Bloomington is a city in and the county seat of Monroe County in the southern region of the U.S. state of Indiana. The population was 80,405 at the 2010 census....
, where he currently lives, in 1977.
Methodology
Sagarin, like the developers of many other sports rating systemSports rating system
A sports rating system is a system that analyzes the results of sports competitions to provide objective ratings for each team or player. Rankings are then derived by sorting each team's ratings and assigning an ordinal rank to each team starting with the highest rated team earning the #1 rank...
s, does not divulge the exact methodology behind his system. He offers two rating systems, each of which gives each team a certain number of points. One system, "Elo chess," is presumably based on the Elo rating system
Elo rating system
The Elo rating system is a method for calculating the relative skill levels of players in two-player games such as chess. It is named after its creator Arpad Elo, a Hungarian-born American physics professor....
used internationally to rank chess players. This system uses only wins and losses, with no reference to the victory margin. The other system, "Predictor," takes victory margin into account. For that system, the difference in two teams' rating scores is meant to predict the margin of victory for the stronger team at a neutral venue. For both systems, teams gain higher ratings within the Sagarin system by winning games against stronger opponents, factoring in such things as home-venue advantage. For the Predictor system, margin of victory (or defeat) factors in also, but a law of diminishing returns
Diminishing returns
In economics, diminishing returns is the decrease in the marginal output of a production process as the amount of a single factor of production is increased, while the amounts of all other factors of production stay constant.The law of diminishing returns In economics, diminishing returns (also...
is applied. Therefore, a football
American football
American football is a sport played between two teams of eleven with the objective of scoring points by advancing the ball into the opposing team's end zone. Known in the United States simply as football, it may also be referred to informally as gridiron football. The ball can be advanced by...
team that wins a game by a margin of 7-6 is rewarded less than a team that defeats the same opponent under the same circumstances 21-7, but a team that wins a game by a margin of 35-0 receives similar ratings to a team that defeats the same opponent 70-0. This characteristic has the effect of recognizing "comfortable" victories, while limiting the reward for running up the score.
At the beginning of a season, when only a few games have been played, a Bayesian network
Bayesian network
A Bayesian network, Bayes network, belief network or directed acyclic graphical model is a probabilistic graphical model that represents a set of random variables and their conditional dependencies via a directed acyclic graph . For example, a Bayesian network could represent the probabilistic...
weighted by starting rankings is used as long as there are whole groups of teams that have not played one another, but once the graph
Graph (mathematics)
In mathematics, a graph is an abstract representation of a set of objects where some pairs of the objects are connected by links. The interconnected objects are represented by mathematical abstractions called vertices, and the links that connect some pairs of vertices are called edges...
is well-connected, the weights are no longer needed. Sagarin claims that from that point, the rankings are unbiased. http://www.usatoday.com/sports/sagarin/bkt0809.htm
Justification
Sagarin's ratings are particularly relevant in the world of AmericanUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
college football
American football
American football is a sport played between two teams of eleven with the objective of scoring points by advancing the ball into the opposing team's end zone. Known in the United States simply as football, it may also be referred to informally as gridiron football. The ball can be advanced by...
and basketball
Basketball
Basketball is a team sport in which two teams of five players try to score points by throwing or "shooting" a ball through the top of a basketball hoop while following a set of rules...
, where, with hundreds of teams in NCAA Division I competition, there is no way a team can play against more than a small fraction of its competitors. Therefore, in determining the participants in championship games and tournaments, it is necessary to distinguish between teams that have compiled impressive win-loss records against strong competition and teams that have defeated weaker opponents.
In addition, sports rating systems are generally of great interest to gamblers. Gamblers use Sagarin's ratings as a source of "Power Rankings," traditionally used as a way to determine the spread between two teams.
However, Sagarin's ratings are being increasingly viewed as antiquated with some speculation that his rankings will no longer be used in upcoming BCS Rankings following this year. This is primarily due to his rankings being viewed as the least reliable and relevant than other computer rankings.
Winval
Along with his former MIT classmate Wayne L. Winston, a professor of decision sciences at Indiana UniversityIndiana University
Indiana University is a multi-campus public university system in the state of Indiana, United States. Indiana University has a combined student body of more than 100,000 students, including approximately 42,000 students enrolled at the Indiana University Bloomington campus and approximately 37,000...
, Sagarin advises the Dallas Mavericks
Dallas Mavericks
The Dallas Mavericks are a professional basketball team based in Dallas, Texas. They are members of the Southwest Division of the Western Conference of the National Basketball Association , and the reigning NBA champions, having defeated the Miami Heat in the 2011 NBA Finals.According to a 2011...
about which lineups to use during games and which free agents to sign using a system called Winval. Winval is modeled after hockey's plus/minus system. The pair are paid over $100,000 for use of the system.
External links
- Article from The Wall Street JournalThe Wall Street JournalThe Wall Street Journal is an American English-language international daily newspaper. It is published in New York City by Dow Jones & Company, a division of News Corporation, along with the Asian and European editions of the Journal....
about why he believes Indiana should be in the Central Time zoneCentral Time zoneIn North America, the Central Time Zone refers to national time zones which observe standard time by subtracting six hours from UTC , and daylight saving, or summer time by subtracting five hours... - Sagarin Ratings, via USA Today
- Jeff's Sports Ratings, Jeff Sagarin's personal page