Criteria-based quantitative analysis of product usability

An approach to quantitative evaluation of product usability during the design and implementation phases of the product life cycle is presented. The evaluation starts by defining a set of usability characteristics, viz. physical, cognitive and affective characteristic. Each of these characteristics is assessed by a set of usability criteria, such as functionality, visual clarity, learmability, etc. The usability criterion is then evaluated by a checklist consisting of a detailed questionnaire. The fuzzy weighted-checklist method with linguistic variables is used for quantitative analysis. Also, the method for quantifying usability improve- ments in iterative design processes is considered. This analysis procides a quantit- ative measure, which reflects the degree of excellence of product usability during the design and development phases.