Improving the Effectiveness of Visual Representations in Requirements Engineering: An Evaluation of i* Visual Syntax

Goal-oriented modelling is one of the most important research developments in the RE field. This paper conducts a systematic analysis of the visual syntax of i*, one of the leading goal-oriented languages. Like most RE notations, i* is highly visual. Yet surprisingly, there has been little debate about or modification to its graphical conventions since it was proposed more than a decade ago. We evaluate the notation using a set of evidence-based principles for visual notation design. The paper identifies some serious flaws in the i* visual notation together with some recommendations for improvement. A broader goal of the paper is to raise the level of debate and stimulate discussion about visual representation in RE research.