What does the abbreviation RPI stand for in NCAA softball rankings?

The abbreviation RPI in NCAA softball rankings stands for Ratings Percentage Index. This metric is used to measure the strength of a team's record in relation to its opponents. The RPI is calculated based on a team's winning percentage, as well as the winning percentage of the teams they have played and the teams those opponents have played (often referred to as "opponent's opponent"). This formula helps to assess the competitive strength of a team across the season.

Using RPI provides a more nuanced understanding of a team's performance beyond just wins and losses. It factors in the quality of both the team’s performance and the opponents' records, making it a crucial tool for determining seeds in tournaments, including the NCAA tournament. By evaluating both a team's performance and the context in which those performances occur, RPI is pivotal for ranking and selection purposes in collegiate softball.