Performance Evaluation as a Tool for Quantitative Assessment of Complexity of Interactive Systems

While research in the field of HCI seems to focus on usability issues real-time safety critical systems deals with specific requirements that make usability only one of the main factors that designers of such systems have to deal with. Indeed, reliability and efficiency are also to be taken into account. This paper presents extensions to previous work done in the field of formal description techniques for interactive systems by adding temporal elements to the ICO formalisms. These temporal elements are used for evaluating in a quantitative way the relative efficiency of different designs. Such results are aimed at supporting design decisions in the design process of safety critical interactive systems.