Comments on Competitive Responsiveness

M Science features many and diverse articles that analyze competitive responsiveness. Although recent Marketing Science editorials (e.g., Shugan 2002) suggest that competitive responsiveness is only a part of a comprehensive competitive marketing strategy, it remains a vital part. For that reason and many others, Marketing Science is particularly proud of this special issue edited by David J. Reibstein and Dick R. Wittink. Before introducing and vigorously applauding both the editors and authors of this excellent special issue, we emphasize that competitive responsiveness raises numerous issues, including whether one can forecast outcomes of new policies based on past observations made under old policies (i.e., the Lucas critique) and decisions regarding which variables should be considered endogenous (Shugan 2004), i.e., determined within the model. Perhaps, normative models are inherently perishable—evolution in market structure requires modifications over time. Also, although complete consistency within the world of the model is aesthetically pleasing, imposing industry-specific exogenous constraints (that might appear unrelated to the modeling assumptions) is sometimes necessary.