User Interface Evaluation

1. User Interface Evaluation CIS 376 Bruce R. Maxim UM-Dearborn

2. Principles of Good Design • State and action alternatives are visible • Conceptual model is consistent with system image • Interface should include mappings that reveal relationships among task stages • User should receive continuous feedback

3. Where is failure likely as users try to accomplish task goals? • Users form inadequate goals • Users fail to find the correct interface object due to poor labeling • Users might not know how to specify or execute a desired action • Users receive poor feedback

4. Building novel widgets that match user task perceptions • Recognize human diversity • Use 8 golden rules of user interface design • Prevent errors, if at all possible

5. 8 Golden Rules of User Interface Design • Strive for consistency • Enable short-cuts for frequent users • Informative feedback • Design dialogs to yield closure • Offer simple error handling • Permit easy reversal of actions • Support internal locus of control • Reduce short-term memory load on user

6. Data Display Guidelines • Consistency • Efficient information assimilation by user • Minimal memory load on user • Compatibility between data display and data entry • Flexibility of user control over data display

7. Getting User’s Attention • Intensity (2 levels only) • Marking (e.g. underscore) • Fonts (up to 3) • Inverse video • Blinking (2 to 4 hertz) • Color (up to 4 standard colors) • Color blinking • Audio

8. Data Entry Guidelines • Consistency • Minimal user input actions • Minimal memory load on user • Compatibility between data entry and data display • Flexible user control

9. Factors affecting choice of evaluation methodology • Stage of design • Novelty of product • Expected number of users • Criticality of interface • Cost of product and budget for testing • Experience of design and evaluation teams

10. Problems with Testing • Can't guarantee perfection • When do stop repairing bugs and ship the prototype? • Testing focuses on normal product use, not extreme

11. Review Methodologies • Expert Reviews • Usability Laboratory Approaches • Surveys • Acceptance Tests • Evaluation During Active Use • Classical Experimental Psychology

12. Expert Review Formats • Heuristic evaluation • Guideline review • Consistency inspection • Cognitive walkthrough • Formal usability inspection

13. Usability Laboratory Approaches • Think aloud • Video tape • Field tests • Destructive testing • Competitive usability testing

14. Surveys • Focus on specific UI features • Plan statistical analysis before data collection • Consider on-line surveys to increase response rates • Use semantically anchored Likert type scales

15. Acceptance Tests • Must be based on measurable criteria • Focus on user behavior and task completion

16. Evaluation During Active Use • Interviews • Continuous user performance data logging • On-line or telephone consulting • On-line suggestion box or trouble reports • On-line bulletin board or newsgroup • User newsletter or conferences