This document discusses methods for evaluating the usability of human-computer interfaces (HCI). It outlines several criteria for evaluation, including usefulness, meaning, aesthetic qualities, sociability, and usability. Usability is broken down into learnability, efficiency, memorability, accuracy, and satisfaction. Both formative and summative evaluation methods are described, such as questionnaires, usability engineering, expert reviews, and usage tracking. Recommendations are provided on selecting representative participants and determining an appropriate sample size for usability testing. Factors that can influence usability, such as cognitive load, personality, gender, culture, and language are also addressed.

1. HCI: evaluatie
KU Leuven, B, 17 February 2014
!
Erik Duval
http://erikduval.wordpress.com
@ErikDuval
1

2. 2
http://www.slideshare.net/erik.duval

3. Criteria for evaluation:
what do you think?

4. criteria
•
Usefulness
•
Meaning
•
(aesthetic) Qualities
•
Sociability
•
Usability

5. http://semanticstudios.com/publications/semantics/000029.php

6. Usability
• Learnability: time to learn the application
• Efficiency: time to perform task
• Memorability: timethat users remember how and what
• Accuracy: number and kind of errors
• satisfaction: subjective feeling
Often a compromise - important to make explicit

7. •
tijdens het ontwikkelen
•
om te verbeteren
•
summatief
•
op het einde
•
om te bewijzen dat “het (niet) werkt”
•
formatief

8. methods
!
- questionnaire
- usability engineering
- by experts
- usage tracking

9. questionnaires
http://hcibib.org/perlman/question.html

10. http://www.cc.gatech.edu/gvu/images/lab/usability-lab.jpg
Usability Lab

11. Usability engineering
• ‘Think-aloud protocol‘
• Video recording with annotation
• Log, remarks, etc. for analysis
• ‘Discount usability engineering’
• Comparative test of user interface

12. By experts
•
•
•
•
in HCI or domain
very effective
delicate relation with developers
target
• identify problems
• suggest solutions
• through checklist of guidelines

13. User tracking
•
google analytics
•
“attention metadata”

14. Participants
• representative
• computer experience, language, task,
motivation, education, etc.
• gender, age
• have to know they are not being evaluated
• relationship
• colleagues, friends, family, ...

15. they are ... human beings
!

17. how many?
Text
http://www.useit.com/alertbox/20000319.html
http://www.useit.com/alertbox/20000319.html

18. • every test user finds fraction L of usability
issues
• independent test users
n
n users find fraction 1-(1-L)
• L=31%
L=8%
85% for n=5, 99% for n=15
35% for n=5

19. Factors that influence usability:
what do you think?

20. Factoren: Cognitief
• cognitive
• fatigue, boredom, stress, fear, ...
• personality
• gender (‘abort’)
• cultural
• i18n

21. Trash can in Thailand

22. ?
@ErikDuval
http://erikduval.wordpress.com
22