Performing User Interface Design - Design Evaluation

Design should be evaluated to check whether it meets the user needs or not once an operational user interface prototype has been created. Evaluation spans a formality spectrum that ranges from an informal test drive in which a user provides an impromptu feedback to a formally designed study.

- After design model has been completed, a first level prototype is created.
- Prototype is evaluated by user.
- User provides designer with direct comments about the efficacy of interface.
- Evaluation cycle continues until no further modifications to interface design are necessary.
- Once first prototype is built, designer collects a variety of qualitative and quantitative data that will assist in evaluating the interface.
- Qualitative data includes questionnaires like simple yes/no, numeric response, scaled response, likert scales, percentage response or open ended.
- Quantitative data can be got by a form of time study analysis can be conducted.

The evaluation criterion applied during early design reviews are:
- length and complexity of written specification of the system.
- number of user tasks specified and average number of actions per task.
- number of actions, tasks, and system states indicated by the design model imply memory load.
- interface styles, help facilities, and error handling protocol provides an indication of interface complexity.