NCAA Basketball - Rankings for Selection Sunday
These pages contains details and results of an approach for ranking US college basketball teams, aimed at guiding the selection of teams for annual NCAA national tournament. For details of the background to the selection process see here
Our approach is to quantify each team's strength of schedule in terms of a benchmark number of wins. This enables us to compare schedules for different teams, in terms of how many more wins we would expect a team to get if they played one schedule rather than another. To calculate this strength of schedule we estimate the average number of wins a fixed team, comparable in ability to the last team in the national tournament, would get if they played that schedule. If a team wins more game than their strength of schedule, then that is evidence that they warrant a bid to the national tournament.
Intepreting the results is relatively straight forward. In 2008/09 Creighton had a win-loss record of 26-7 and Boston College one of 22-11. While Creighton won 4 more matches than Boston College, their strength of schedule is 26.5 wins and Boston College's is 21.5 wins. Thus their schedule is 5 wins easier than Boston College's -- and thus we rank Boston College to have the better record, by one win.
The strength of schedules are calculated by fitting a statistical model to all regular season results to date. This is used to estimate the ability of each team, and thus the likelihood of winning a match against that team. We also give a margin of error, which gives an indication of how accurate the resulting estimates of the strength of schedule are. This can be used to highlight the teams for which there is uncertainty about whether their record deserves a bid to the national tournament.
Below are Frequently Asked Questions page, which contains more detail of the ranking procedure, and the interpretation of the results.
Full details of the method can be found in the academic paper Calculating Strength of Schedule, and Choosing Teams for March Madness.
There are around 340 division I US college basketball teams, almost all of whom belong to one of 31 conferences. Each March there is a national basketball tournament (known as March Madness). This is a knockout tournament, in which (from 2011) 68 teams take part. The field of 68 consists of 31 conference champions, and a further 37 teams that are picked by committee. The announcement of these 37 teams, and the draw for the tournament, is made on Selection Sunday.
The difficulty with selecting the 37 teams for the tournament is that the strength of schedule of each team varies greatly. For example in 2009, Arizona were given entry to the national tournament, with a Win-Loss record of 19-13, whereas Creighton, with a 26-7 record, were not. Picking the 37 teams with the best win-loss record is not appropriate.