Serving the scholastic field hockey and lacrosse community since 1998

Aug. 18, 2015 — If metrics maketh (wo)man ….

If you’ve been on this site enough times, especially in the days before the brackets are released for the NCAA Division I field hockey and women’s lacrosse brackets, you’ve heard the term RPI.

No, not the engineering school near Albany, N.Y., but Ratings Percentage Index. It is a formula, based upon a team’s results and the results of the teams they play, which can serve as a prime index or a tie-breaking factor as to which teams play whom in a filled bracket — or even if a team makes the tournament.

This site did an experiment a couple of years ago with a simplified version of this computer formula in the Weekly Top 10. It showed, frankly, a gulf in terms of the strength in schedule between Hummelstown Lower Dauphin (Pa.) — a team which has to play the likes of Hershey (Pa.) and Palmyra (Pa.) two to three times a year — and Watertown (Mass.), which has to try to improve itself without a lot of non-conference opposition but has willed its way to 138 straight games without a defeat.

The Colorado High School Athletic Association (CHSAA) announced a week ago that it would be using an RPI formula for seeding all high-school playoff competitions beginning with the fall of 2016. The formula would take into account a team’s winning percentage, the winning percentage of their opponents, and the winning percentage of their opponents’ opponents.

The RPI is an elegant formula, first used in 1981 for the NCAA Division I men’s basketball tournament. It was thought that, after the Boston College point-shaving scandal, that margins of victory could be taken out of the equation as to who to seed where. The 1981 men’s tournament, which featured a number of dramatic finishes clustered around the afternoon of March 14th, justified the new seeding formula.

Websites, for both college and high school sports, use the formula to track teams and to rate how well they do. For the past decade, for example, has used a version of the RPI formula to determine the best boys’ and girls’ lacrosse teams in the country.

Metrics can help try to figure out which team is more likely to be victorious on a particular day, but they do not take into account human elements such as deception, cunning, determination, and motivation.

This is, of course, why you play a game between two teams on an acre of grass (or a reasonable facsimile thereof) and have at it.


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