Usability evaluation: an empirical validation of different measures to quantify interface attributes

One of the main problems of standards (e.g. DIN 66234, ISO 9241) in the context of the usability of software quality is that they cannot be measured in product features. We present a new approach to measure user interface quality in a quantitative way. First, we developed a concept to describe user interfaces on a granularity level that is detailed enough to preserve important interface characteristics and is general enough to cover most of the known interface types. We distinguish between different types of 'interaction points'; with these, we can describe several types of interfaces: both character-based user interfaces (CUIs) (command languages, menus, form fill-in, etc.) and graphical user interfaces (GUIs) (desktop metaphor, direct manipulation, multimedia, etc.). We carried out two different comparative usability studies to validate our quantitative measures. The results of one other published comparative usability study can be predicted. The results of six different interfaces are presented and discussed