Analyzing a process like design is difficult because only its effects can be observed. Whereas traditional cognitive task analysis, e.g. using computational cognitive models, models the process itself, we concentrate on its effects in the form of the designers' use of representational language to describe the artifact they are designing. Analysis consists of activities such as identifying the objectives subproblems, and identifying issues for research. Description involves clarifying the situation further, conducting research, and defining a problem specification.
Evaluation is characterized by 'stepping back' and reflection.
It involves evaluating the prototype with respect to the criteria, and identifying aspects for improvement and redesign. Each of these activities is concerned with different representational aspects of the artifact. Since an artifact must fulfill a certain purpose in a larger context, analysis deals with the function of the artifact. The description phase deals with the behavior in the given context and with the necessary structure, i.e. the parts and their causal relationships that lead to the behavior. During evaluation the designer tests whether the artifact's behavior implements the required function.