Understanding changes in use cases: A case study

Requirements change and so (should) do requirements artifacts, such as use cases. However, we have little knowledge about which changes requirements engineers actually perform on use cases. We do not know what is changing, at which locations use cases change and need a deeper understanding of which changes are problematic in terms of difficult or risky. To explore these challenges from an industrial point of view, we conducted a mixed methods case study in which we analyze 15 month of changes in use cases in an industrial software project. The study provided interesting observations for both practitioners and researchers involved: First, the most frequently changing use cases had an issue in their structuring. Second, alternative flows (i.e., variations or extensions of the main flow) were especially prone to changes. Third, changes in content (semantic changes) and in presentation of the content (syntactic changes) happen similarly frequently. Last, a qualitative and quantitative analysis aiming at a deeper understanding of problematic changes identified taxonomy changes, as well as locally or temporally dispersed changes as particularly difficult and risky. In this paper, we contribute a first empirical inquiry for understanding the maintainability of use cases: The presented study provides empirical evidence that there are particular maintenance risks and suggests to continuously analyze local and temporal dispersion.