Usability Evaluation [2nd ed.]

Put simply, usability evaluation assesses the extent to which an interactive system is easy and pleasant to use. Things aren’t this simple at all though, but let’s start by considering the following propositions about usability evaluation: Usability is an inherent measurable property of all interactive digital technologies Human-Computer Interaction researchers and Interaction Design professionals have developed evaluation methods that determine whether or not an interactive system or device is usable. Where a system or device is usable, usability evaluation methods also determine the extent of its usability, through the use of robust, objective and reliable metrics Evaluation methods and metrics are thoroughly documented in the Human-Computer Interaction research and practitioner literature. People wishing to develop expertise in usability measurement and evaluation can read about these methods, learn how to apply them, and become proficient in determining whether or not an interactive system or device is usable, and if so, to what extent. The above propositions represent an ideal. We need to understand where current research and practice fall short of this ideal, and to what extent. Where there are still gaps between ideals and realities, we need to understand how methods and metrics can be improved to close this gap. As with any intellectual endeavour, we should proceed with an open mind, and acknowledge that not only are some or all of the above propositions not true, but that they can never be so. We may have to close some doors here, but in doing so, we will be better equipped to open new ones, and even go through them.