Maria Francesca Costabile Dip. Informatica, Università di Bari, Via Orabona 4, 70125 Bari, Italy
Usability is a crucial aspect of the overall quality of any kind of interactive application. Recent research has outlined the need for systematic evaluation techniques. Up to now, usability evaluation has been mainly performed for general features of applications, such as interaction style, presentation aspects, choice of the icons, etc., common to all interactive systems ( Nielsen 1993). Most of existing works lack a general, systematic framework for carrying out usability evaluation of different features of an application+ADs- moreover, only a few papers discuss evaluation of specific features that are not strictly related to presentation aspects. Despite the large diffusion of hypermedia, both off-line hypermedia (popular in commercial CD-ROMs) and on-line hypermedia (Web sites), there has been very little work on usability evaluation of such systems.
We have developed a novel evaluation methodology named SUE (Systematic Usability Evaluation) which combines in an original manner inspection methods, involving expert evaluators only, with empirical methods, based on users observations ( Costabile et al. 1997). The basic assumption of SUE is that the in- depth evaluation of an interactive application is obtained through more than one evaluation process, each one conducted from a different perspective, i.e., focusing on a specific set of application features. Each evaluation process starts by inspecting the application. Then, if needed, an empirical test can be conducted for confirming the inspection findings with the help of real users. Since the empirical test is designed on the basis of the inspection results, the testing is better focused, and the real user resources are better optimized, with the overall consequence of making the evaluation less expensive. The most innovative aspect of the SUE methodology is the use of abstract tasks to drive the inspection activity. An abstract task is an evaluation pattern which precisely describes the activities that an evaluator must perform during the inspection phase. Another characteristic of SUE is the systematic use of application models, where the term model is used in a broad sense, for indicating a set of primitives, concepts and terms capable of