The NCAA developed the college basketball RPI ratings back in 1981 as an additional piece of reference material when selecting and seeding teams for the men's basketball tournament. Each year when March Madness rolls around the importance of the RPI(Ratings Index Percentage) seems to get over-hyped by the media and by many college basketball gurus across the internet. The NCAA actually considers several factors when evaluating teams for the tournament. College basketball RPI ratings are just one piece of the puzzle that the tournament committee contends with.
The formula for the college basketball RPI ratings is quite simple. It's based on wins, who you have played, and who your opponents have played. Road wins are weighted heavier than home wins. Home losses are weighted heavier than road losses.