ABSTRACT
Observational studies such as user trials are at the core of user-involved product assessment. Potential users are observed when operating a product. Generally, their activities reveal usability problems. It is commonly accepted that the earlier in a design process that usability problems can be identified the better, as the opportunity for improvement by design is less complicated in early phases. During the early phases of a design process, prospective users may be observed operating design models, e.g., drawings, foam models, computer simulations, or prototypes (cf. Moggridge 2007). In our study, a design model represents a design at some point in its development (Figure 27.1). The assumption underlying user trialing with design models is that participants will indeed approach the model as representing a design.
