Managers need to know if a theory applies in their situation, if they are to trust it. A very useful book on this topic is Robert K. Yin’s Case Study Research: Design and Methods (Beverly Hills, CA: Sage Publications, 1984). Building on Yin’s concept, we would say that the breadth of applicability of a theory, which Yin calls its external validity, is established by the soundness of its categorization scheme.
