Evaluating the Completeness and Granularity of Functional Requirements Specifications: A Controlled Experiment

Requirements engineering (RE) is a relatively young discipline, and still many advances have been achieved during the last decades. In particular, numerous RE methods have been proposed. However, there is a growing concern for empirical validations that assess RE proposals and statements. This paper is related to the evaluation of the quality of functional requirements specifications, focusing on completeness and granularity. To do this, several concepts related to conceptual model quality are presented; these concepts lead to the definition of metrics that allow measuring certain aspects of a requirements model quality (e.g. degree of functional encapsulations completeness with respect to a reference model, number of functional fragmentation errors). A laboratory experiment with master students has been carried out, in order to compare (using the proposed metrics) two RE approaches; namely, Use Cases and Communication Analysis. Results indicate greater quality (in terms of completeness and granularity) when communication analysis guidelines are followed. Moreover, interesting issues arise from experimental results, which invite further research.