Usability Properties in Dialog Models

Usability has gained a lot of attention in the design community and it is one of main goals of every design project. Evaluating usability is usually done with end-users after a prototype has been built and there are not many techniques available that allow usability evaluation during the early design phases. Current dialog modeling techniques generally do not deal with usability aspects, as they are often functional based models, dealing only with states and state changes. This paper investigates how usability aspects can be incorporated into dialog models so that usability can be evaluated during the design process without doing usage tests. A set of measurable properties is given which together could give an indication about the usability of the design, This way, some usability aspects can be covered early in the design process without the need for an executable prototype or end-users.