|
Ratings Percentage Index RPI (ratings percentage index) is a rating that applies to a team's record and schedule such that the stronger the opponents, the higher the RPI rating or, conversely, the weaker the opponents, the lower the RPI rating. In order to tabulate an RPI rating, the opponent's strength has to be evaluated by examining the W-L record of the opponents as well as the W-L record of the opponent's opponents. RPI = 1/4 * team's record + 1/2 * opponent's record + 1/4 * opponent's opponent's record Records are in the usual form of a win proportion: Wins / (Wins + Losses). Ties are treated as 1/2 win + 1/2 loss. Note: when computing the opponent's record, do NOT include the game(s) with the team under consideration and when consider the opponent's games against their opponent's, do NOT consider the opponent's game in the calculation. Here is an example of the computation: A team has played 8 of its 12 games through the season. The team's record is 7 wins and 1 loss or 0.875. The records for the opponents are as follows:
Team A 5 3 62.5 %
Team B 4 3 57.1 %
Team C 2 5 28.6 %
Team D 3 4 42.8 %
Team E 7 1 87.5 %
Team F 2 5 28.6 %
Team G 2 5 28.6 %
Team H 9 0 100.0 %
------
34 26 54.5 %
Note that the 54.5% is not based on 34/60 (56.66%) but the average percentage of each opponent's
percentage.
The records for each opponent's opponents are:
Team A 42 18 75.0 % Based on average % of all opponent's opponents
Team B 22 24 50.2 % Not based on total wins / total games
Team C 18 18 48.3 %
Team D 32 22 60.0 %
Team E 30 31 53.0 %
Team F 29 15 62.4 %
Team G 37 16 64.5 %
Team H 39 27 61.5 %
-------
249 171 59.4 %
Note 59.4% is not based on (249/(249+171) but the average of percentages
in the last column.
The RPI for our example team is then computed as follows:RPI = 0.25 * 0.875 + 0.50 * 0.545 + 0.25 * 0.594 = 0.600 The second and third components define the Strength of Schedule of a team. |