Olga Liskin, Raphael Pham, Stephan Kiesling, Kurt Schneider:
»Why We Need a Granularity Concept for User Stories«

User stories are a widespread instrument for representing requirements. They describe small user-oriented parts of the system and guide the daily work of developers. Often however, user stories are too coarse, so that misunderstandings or dependencies remain unforeseeable. Granularity of user stories needs to be investigated more, but at the same time is a hard-to-grasp concept. This paper investigates Expected Implementation Duration (EID) of a user story as a characteristic of granularity. We want to find out, whether it is suitable as a quality aspect and can help software teams improve their user stories. We have conducted a study with software engineering practitioners. There, many user stories had a relatively high EID of four or more days. Many developers state to have experienced certain problems to occur more often with such coarse user stories. Our findings emphasize the importance to reflect on granularity when working with user stories.