by Eric Steinhouse (@mesksk)

RPI calculations have been used by NCAA basketball to assist with selecting and seeding the NCAA tournament.  Thanks to the new availability of the master schedule on Missouri Water Polo , I have attempted to calculate an RPI (Ratings Percentage Index) for the St. Louis HS water polo teams as of 4/25/12.

Given some of the close rankings (see #6-7, #8-11).  Obviously there are some important games coming up at the Lindbergh and JBS Invitationals this weekend that could alter the rankings before the District seeding meeting on Sunday.

FYI, a school’s RPI ranking consists of three factors that are weighted as follows:

1.  St. Louis Winning Percentage — 25 percent of the RPI

2.  Opponent’ Winning Percentage– 50 percent of the RPI

3.  Opponents’ Opponent Winning Percentage — 25 percent of the RPI

I also ranked teams based on their strength-of-schedule, which combines factors #2 & 3 above.

TEAM                           RPI                    SOS Rank

1.   SLUH                      0.669                2

2.   P-West                    0.626                7

3.   MICDS                    0.605                1

4.   DeSmet                  0.599                4

5.   Ladue                     0.566                8

6.   Kirkwood                0.548                3

7.   Lindbergh                0.546                9

8.   P-South                  0.534                11

9.   P-North                   0.532                6

9.   Marquette                0.532                5

11. John Burroughs       0.525                9

12. Summit                   0.495                18

13. Chaminade              0.469                14

14. Oakville                   0.461                16

15. Lafayette                 0.436                12

16. Ft. Zumwalt             0.416                15

17. Clayton                   0.400                19

18. P-Central                 0.396                13

19. Eureka                    0.380                21

20. U-City                      0.345                17

21. Mehlville                  0.328                20

a)     Only games against St. Louis teams used for calculations (out of state W-L records too unwieldy)

b)    For opponents winning percentage calculations, W-L records do NOT include wins/losses against the original team

c)     I did not attempt to look at home-away (makes my spreadsheet overly complicated)

d)    RPI excludes margin of victory, which can be manipulated by running up the score