Bracketology is the process of predicting the field of the NCAA Basketball Tournament, named as such because it is commonly used to fill in tournament brackets for the postseason. It incorporates some method of predicting what the NCAA Selection Committee will use as its Ratings Percentage Index in order to determine at-large (non-conference winning) teams to complete the field of 68 teams, and, to seed the field by ranking all teams from first through sixty-eighth.