Usability as a goal for the design of computer systems

The goal of all software engineering is to construct computer systems that people find usable and will use. Usability is an overall goal that encompasses both system functionality and user interface issues. Assessing usability is vital for those acquiring software packages as well as for those designing and developing software. The concept is also worth scientific research. Still, defining or measuring usability is problematic both in the course of sys-tem development projects and in research settings. The measures promoted by some recent usability studies are inadequate and even give rise to false assumptions. The concept of usability is a difficult one since the factors affecting it are defined only in the use context. It is not possible to evaluate the usability of a computer system without tying it up with the actual activities the user wants to use the system for. This claim is supported by a series of case studies in decision support systems. These studies have clearly shown that no list of usability evaluation criteria suffices in the long run; instead, perceived usability depends heavily on (organizational) context. Still, it is an important goal in every context, not only in decision support systems.