Player Evaluation Metrics
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|There are 4 entries in the glossary.|
|Real Plus Minus (RPM)|
Author: Jeremias Engelmann
A metric provided by former Phoenix Suns consultants Steve Ilardi and Jeremias Engelmann, based on Engelmann's version (xRAPM) of Regularized Adjusted Plus-Minus
Real Plus Minus is the player's average impact in terms of "net point differential" per 100 offensive and defensive possessions. RPM can be broken down to offensive and defensive metrics:
Total rebound percentage is estimated percentage of available rebounds grabbed by the player while the player is on the court.
Total Rebound Percentage=100*(Total Rebounds*(Team Minutes Played/5))/(Minutes Played*(Team Total Rebounds + Opponent Team's Total Rebounds))
|Regularized Adjusted Plus Minus (RAPM)|
Author: Joe Sill
In "Regularized Adjusted Plus-Minus" (RAPM), the goal is to provide more accurate results by employing a special technique called "ridge regression" (a.k.a. regularization). It significantly reduces standard errors in Adjusted Plus-Minus (APM).
Conventional adjusted plus-minus is shown to do a poor job of predicting the outcome of future games, particularly when fit on less than one season of data. Adding regularization greatly improves accuracy, and some player ratings change dramatically. The enhancement with the RAPM is a Bayesian technique in which the data is combined with a priori beliefs regarding reasonable ranges for the parameters in order to produce more accurate models. That is what ridge regression (a.k.a. regularization) does.
Comments: RAPM is about twice as accurate as an APM using standard regression and using 3 years of data, where the weighting of past years of data and the reference player minutes cutoff has also been carefully optimized.
The Roland Rating is a basic, quick look at the player that represent a player's value to a particular team and are not intended to be an accurate gauge of the ability and talent of the player away from the specific team. It represents how successful a player is with a given team.
The on court +/- number represents the team's net points with the player on the floor per 48 minutes, while the off court number is the team's net with the player off the floor per 48 minutes. The Roland Rating is the difference between the two, with a positive number indicating the team has played better with the player than without.