ABSTRACT
This chapter argues that model-based evaluation is a valuable supplement to conventional usability evaluation and analyzes the approaches for performing model-based evaluation. It presents several high-level issues in constructing and using models for interface evaluation and comment on the approaches in the context of those issues. Model-based evaluation can be best viewed as an alternative way to implement an iterative process for developing a usable system. The model itself summarizes the design and can be inspected for insight into how the design supports the user in performing the tasks. The basic scheme for using model-based evaluation in the overall design process is that iterative design is done first using the model and then by user testing. In task network models, task performance is modeled in terms of a PERT-chart-like network of processes. Building a model and using it to obtain predictions may indeed involve substantial detail work.
