Empirical assessment of UML class diagram layouts based on architectural importance

The paper presents a family of experiments that investigate the effectiveness of different layout techniques for class diagrams in the Unified Modeling Language (UML). Three different layout schemes are examined based on architectural importance of class stereotypes. The premise is that layout techniques for UML class diagrams significantly impact comprehension. Both traditional questionnaire-based studies as well as eye-tracking studies are done to quantitatively measure the performance of subjects solving specific software maintenance tasks. The main contribution is the detailed empirical validation of a set of layout techniques with respect to a variety of software maintenance tasks. Results indicate that layout plays a significant role in the comprehension of UML class diagrams. In particular, there is a significant improvement in accuracy, time, and visual effort for one particular layout scheme, namely multi-cluster. The end goal is to determine effective ways to adjust the layout of existing UML class diagrams to support program comprehension during maintenance.