17.4. Predictive evaluation
Inspection methods
Cognitive walkthrough
Steps through the interface
Startup
- Task description
- Initial goals
Actions
- Correct goals
- Problems forming correct goals
- Failure to add goals
- Failure to drop goals
- Addition of spurious goals
- No-progress impasse
- Premature loss of goals
- Supergoal kill-off
- Problems identifying the action
- Correct action does not match goal
- Incorrect action match goals
- Problems performing the action
- Physical difficulties
- Time-outs
Modelling - the keystroke level model
- Specification of systems functionality
- Task analysis showing how tasks are performed using the equipment
Time to execute a task consists of
- TK
- Time for keystrokig
- TP
- Time for pointing
- TD
- Time for drawing
- TM
- Time for mental operation
- TH
- Time for homing
- TR
- Response time
- Different tasks can be described this way and compared without experiments
- The designer can compare the differences and complexities of tasks