The NFCA, in conjunction with
mathematician Warren Nolan, will once again release a
ratings percentage index (RPI) for Division I softball.
The first rating was released April 3, with the No. 1
team in the
USA Today/NFCA Division I Top 25 Poll, Florida, atop
the RPI.
2009 NFCA Simulated Ratings Percentage Index
The Gators are 34-3 through games of Sunday, March 29,
2009. The Southeastern Conference leads the Conference
RPI at the first date of release.
What is the RPI?
The RPI is a mathematical calculation used to help
determine teams’ success, using a calculated strength of
schedule and won-loss percentage.
The NCAA develops its own RPIs to give selection
committees another tool when selecting teams for the
NCAA championships. This year, the NCAA will release its
softball RPI on a bi-weekly basis, with the first one
released on March 31. The NFCA and NCAA RPIs are a
little different since the NCAA uses bonuses and
penalties that it does not release to the general
public.
“We first developed the RPI in the 2005 season as a
benefit for our members, since the NCAA was not making
its RPI available to coaches,” said NFCA Executive
Director Lacy Lee Baker. “Although the NCAA will release
an RPI this year during the season, we think the NFCA
weekly compilation and the strength of schedule is still
interesting and helpful. From reports we’ve received
from the softball community, it’s apparent that coaches
and fans agree,” Baker continued.
In addition, the NFCA RPI also is used as a tool by
voters in the USA Today/NFCA Coaches poll, and by the
coaches and committee members selecting Louisville
Slugger All-Region and All-American teams.
RPI Calculations
The same basic formula is used in NCAA Division I men’s
and women’s basketball, baseball and softball; however,
there are minute differences (penalties and bonuses)
that are specific to each sport. For example, there may
be a small penalty if a Division I school plays a
non-Division I opponent. There may be a small bonus for
beating a top 25 team.
When determining the RPI for each team, the following
basic formula is used:
25% -- Winning percentage.
50% -- Opponents’ winning percentage.
25% -- Opponents’ opponents’ winning percentage.
Although the NCAA publishes the basic formula, it does
not release the mathematical bonuses and penalties
specific for each sport. It is important to note that
the NFCA RPI may not be exactly the same as the NCAA RPI,
since the NCAA will not release its bonus and penalty
calculations. However, the two should be close and the
NFCA RPI should be an indication of where a team stands.
The NCAA does not endorse the NFCA RPI.
What are the procedures used in developing the NFCA
RPI?
Step 1
To prepare an RPI, the mathematician must have every
score in the nation. All of the 30 conferences that
sponsor softball agreed to send the NFCA an XML file.
The XML files, which are prepared weekly by conference
personnel to send their conference members’ game
statistics and scores to the NCAA, are developed through
the scoring program, The Automated Scorebook.
Scores for these conferences, as well as independents,
are gathered by the NFCA and sent to the mathematician
in a special format.
Step 2
The NFCA has selected Nolan, a mathematician who is
involved in calculations for football’s Bowl
Championship Series, to calculate the RPI. He also
publishes his own basketball and baseball RPI.
Nolan receives the XML files and other scores by
Wednesday. After the information is proofed and
corrected by the NFCA, the RPI is published on NFCA.org
on Fridays. Therefore, the RPI is not final until
Fridays.
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