Technical Overview of Safe3Step (S3S): Power Ratings and quality wins for selecting at-large teams to the NCAA Division I Men's Lacrosse Championship

This document describes a system for selecting teams to the NCAA Men's Division I Lacrosse Championship Tournament called "Safe3Step" (S3S) that was developed in conversation with the NCAA Lacrosse Selection Criteria and Ranking Committee (SCR) with the objective of improving on the Ratings Percentage Index (RPI). S3S employs three steps that: 1) evaluate the strength of each team based on score data, 2) award S3S points to each team based on the quality of its wins and losses, ranking teams accordingly, and 3) examine each pair of teams with adjacent rankings, swapping ranks if the lower-ranked team has a better head-to-head record against the higher-ranked team. Safe3Step is not entirely new, but it improves on other "quality win" methods by using Power Ratings to identify team strengths, respecting head-to-head records, and adhering to standards of simplicity, transparency, and objectivity. Empirical analysis is left to future work.