Abstract
The purpose of this study is to propose an index for evaluating the offensive ability of American football teams. Up to now, there have been many indices to evaluate the ability such as QB rating, gained yardage, the number of pass catches, and the number of T.D. However, any of the indices can not represent the offensive ability meaningfully, for they depend on the defense ability as well. In this study, we propose a new Offensive Ability Index which independent of the defense ability in terms of the Markov chain.
