an effort and time based measure of usability
The hypothesis of this research is that usability relates to the physical effort that is required in order to use software in the accomplishment of interactive tasks. Implications of this hypothesis are significant since effort is an objective quantity that can be measured efficiently in a relatively non-expensive and non-invasive fashion. Based on this hypothesis, this work proposes metrics for measuring operability, learnability, and understandability. Usability testing is an essential element of a robust validation process. Nevertheless, evaluating software usability is an expensive and time consuming activity, frustrating both developers and managers. Developers are frustrated because it is a critical part of their work; yet, they do not have solid information on how to address it. Managerial frustration lies in the fact that correcting usability defects is an iterative process, and the amount of preparation required can significantly delay a project. Hence, wider utilization of usability testing requires reducing the cost and simplifying the approach. This paper proposes a framework for measuring effort and using the effort measurements to assess usability. The framework has two main components: One bases effort on keystrokes and mouse usage; the second uses a model of the eye muscles along with eye-movement tracking to estimate eye effort. The two components are independent, but they could be used in tandem. Tracking time and effort may not be as precise an evaluation of usability. Nevertheless, it can provide a good screening tool to reduce development cost.
usability metrics operability understandability validation quality leanability