Modeling and Reasoning with Changing Intentions: An Experiment

Existing modeling approaches in requirements engineering assume that stakeholder goals are static: once set, they remain the same throughout the lifecycle of the project. Of course, such goals, like anything else, may change over time. In earlier work, we introduced Evolving Intentions: an approach that allows stakeholders to specify how evaluations of goal model elements change over time. Simulation over Evolving Intentions enables stakeholders to ask a variety of 'what if' questions, and evaluate possible evolutions of a goal model. GrowingLeaf is a web-based tool that implements both the modeling and analysis components of this approach. In this paper, we investigate the effectiveness and usability of Evolving Intentions, Simulation over Evolving Intentions, and GrowingLeaf. We report on a between-subjects experiment we conducted with fifteen graduate students familiar with requirements engineering. Using qualitative, quantitative, and timing data, we show that Evolving Intentions were intuitive, that Simulation over Evolving Intentions increased the subjects' understanding and produced meaningful results, and that GrowingLeaf was found to be effective and usable.