A Consistent Weighted Ranking Scheme with an Application to NCAA College Football Rankings

The NCAA college football ratings, in which the "so-called" national champion is determined, has been plagued by controversies the last few years. The difficulty arises because there is a need to make a complete ranking of teams even though each team has a different schedule of games with a different set of opponents. A similar problem arises whenever one wants to establish a ranking of patents or academic journals, etc. in which the raw data are (incomplete) bilateral citations or interactions among objects. This paper develops and estimates a simple consistent weighted ranking (CWR) scheme which, in the sports world, depends on four parameters (winning vs. losing and the relative importance of home vs. away games). In most ranking problems, there are not explicit criteria to evaluate the success of proposed rankings. NCAA college football has a special structure that enables the evaluation of each ranking scheme. Each season is essentially divided into two parts: the regular season and the post season bowl games. If a ranking scheme is accurate it should correctly predict a relatively large number of the bowl game outcomes. We use this structure to estimate the four parameters of our ranking function using "historical" data from the 1999-2003 seasons.