NCAA basketball strength of schedule is based on the average winning percentage of all the opponents a given team has played so far during the season. College basketball strength of schedule goes one step further to include the average winning percentage of all the schools that the given team's opponents have played. The SOS formula is easy:
(2/3)*opponents' average winning percentage + (1/3)*opponents' opponents' average winning percentage = SOS
The 2 to 1 ratio used in the above NCAA basketball strength of schedule formula is in line with the SOS component of the Ratings Percentage Index(RPI) that the NCAA uses as a guide when selecting and seeding teams for the NCAA men's basketball tournament.