An Effort-Based Approach to Measuring Software Usability
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An Objective Measure of Usability Using Effort Estimation Design and implementation of usable human computer interface (HCI) systems involves expensive, primarily cognitive based, usability testing and evaluation techniques. This complicates the development process and may cause software companies and software engineers that are more familiar with objective testing methodologies to reduce or completely avoid the usability testing stage, reverting to best practice techniques, and producing HCI systems that lack usability. This research is based on the assumption that usability of HCI systems is directly related to the amount of mental and physical effort expended by the user throughout the interaction. It explores and exploits the utility of an objective, relatively easy to measure, and engineering oriented usability metric. A mathematical model of interaction effort is formulated. The model transforms data related to primitive interaction events such as keyboard keystrokes, mouse key clicks and Mickys traversed by the mouse along with eye tracking data into an effort metric. A carefully crafted set of user interaction goals employing scenario based test design techniques is implemented. Data is collected using logging programs that record goal completion time along with keyboard, mouse, and eyes interaction events. The recorded information is reduced to a statistically meaningful data-set that is used to evaluate the validity of the research assumptions. Experimental results support the hypothesize. Furthermore, they are prompting several interesting finding that merit further research and investigation. This is the first research that carries the intuitive idea of relation between effort and usability all the way to the "field" by recording and processing effort based metrics obtained from subjects while interacting with real complex systems.