Visual variability analysis for goal models

One of the benefits of goal-oriented requirements engineering is the possibility of conducting formal analysis in order to evaluate alternative solutions of goal models. Superficially, goal analysis seems like an optimization technique. In contrast to such techniques, however, goal analysis does not aim at optimal solutions, but rather "good enough" ones (Simon, 1996). Moreover, goal analysis has to blend quantitative with qualitative techniques to account for subject matters that are not readily quantifiable. The analysis of the interplay of nonfunctional softgoals and functional goals at a high level of abstraction is an important element of goal analysis for the requirements engineer, especially so when dealing with requirements variability. This work proposes a visual variability analysis technique and describes an implemented tool that supports it.