In this dynamic age of corporate acquisitions, mergers, and enterprise integration, decisions concerning the evaluation and selection of information systems require comparing the functionality of each candidate system to the intended business activities that it will support. However, consensus on the definition of business activities used to support this evaluation is rare. What is needed is a referent business activity model that defines the business in a manner to serve as the basis for determining how well each candidate system supports the business. This paper 1) defines the referent business activity model concept; 2) provides an example from a case study of business activity modeling; and 3) demonstrates the utility of this model in defining functional requirements for selecting the optimal system from a set of 30 legacy systems to be used throughout the United States Department of Defense (DoD). Twenty-nine DoD business experts were able to construct a referent business activity model consisting of 65 business activities organized in a hierarchical manner. These activities served as the foundation for a questionnaire of 165 questions used to select three information systems out of the over 300 known systems that supported one or more of the 65 business activities. This experience demonstrated the feasibility of achieving consensus among business experts on one referent business model. It also demonstrated the utility of that model in evaluating legacy systems. This case provides a detailed example that business experts can bridge the gulf of ambiguous systems requirements that exists between real-world business activities and the information systems that support them
