User Modeling

These are explicit respresentations of users that predict user behavior and product usability.

Keystroke Level Model

  • Rules for applying the KLM
  • Predicts task length for an expert user
  • Review example in class

We will practice this method on this unit converter.

Note Sauro's approach of using composite operators (screen shot of tool).

Cognitive models of user interaction

GOMS (Goals, Operators, Methods, Selection) hierarchical analysis

The four components of a GOMS analysis

  • Goal -- desired result; does not specify means for achieving result
  • Operator -- a primitive step for achieving a goal; often a user action
  • Method -- a plan for achieving a goal consisting of operators
  • Selection -- a rule for recommending a method that achieves a goal

Properties

  • Explicitly represent the user's knowledge and actions in the form of goals and subgoals
  • The depth of the hierarchy indicates the complexity of the product and task
  • Usage statistics of task components can be applied to other tasks that use the same components
  • Article reviewing GOMS approaches

We will review a GOMS example in class.

Issues for discussion

  • Advantages of user modeling
  • Costs of user modeling