Evaluate Structural Variables

Structural variables are the factors that define the arena of any human-computer interaction. They vary between texts, users, and user environments. Identifying their values—or their range of values—is an essential initial step in the formulation and planning of any evaluation. Common structural variables include:

	Task variables: Including the domain of required tasks and an overall model of goals for achievement
	User Variables: Including intellectual abilities (both general and technical), cognitive style (risk preference, curiosity, persistence), experience and frequency of system use, knowledge (of method, concept, and task), and perceptual-motor skills (e.g. typing rate, mouse skills)
	Computer Variables: Including dialogue style, command syntax, naming conventions, display layout, input devices, and response times