An Experimental Comparison of Two Navigation Techniques for Requirements Modeling Tools

In Requirements Engineering, many modeling tasks require viewing different parts of a model concurrently. However, traditional zoom+scroll navigation uses a single focus zoom, i.e., at a given point in time, a user can zoom in on a single spot in the model only. Therefore, new focus+context navigation techniques have been proposed that allow multiple foci at the same time. In this paper, we report on an experiment with students where we compare the participants' performance when using a requirements modeling tool with traditional zoom+scroll navigation vs. one with so-called FlexiView navigation which is a focus+context technique with multiple foci. The participants had to perform typical modeling tasks such as searching, editing, and traversing a model. All tasks were performed on medium-sized tablets with a tool for manipulating so-called ImitGraphs. ImitGraphs are enriched node-and-edge diagrams that can mimic various diagram types such as class, activity, or goal decomposition diagrams. We found that navigation with FlexiView outperformed zoom+scroll navigation with respect to task completion time, number of mistakes, cognitive load, and user satisfaction.