Design

1
Design UsabilityHUMBAS FS03

• Sisse Siggaard Jensen
• associate professor
• Communication Studies

2
Programme

• 0900-0945 Design Usability Intro
• 0945-1000 Test og evalueringsgrupper
• 1000-1015 Kaffepause
• 1015-1035 Design walk-through
• 1035-1100 Test laboratorium, session 1
• 1100-1115 Kaffepause
• 1115-1200 Test laboratorium, session 2

3
Design

• User-friendly - a warm, fuzzy feeling (p. 27)
• User Centered Design (UCD)
• Participatory design
• Focus group research
• Surveys
• Design walk-throughs
• Paper and pencil evaluations
• Expert evaluations
• Usability testing
• Field studies
• Follow-up studies

4
System acceptability

• Social acceptability
• Practical acceptability
• Cost
• Compatibility
• Reliability
• Usefullness
• Utility Wether the functionality of the system
  in principle can do what is needed (Nielsen
  1993)
• Usability How well users can use the
  functionality (Ibid)

5
Usability

• Learnability
• Efficiency of Use
• Memorability
• Few and Noncatastrophic Errors
• Subjective Satisfaction

6
Measuring usability

• Usability is measured relative to certain users
  and certain tasks
• Representative group of users
• Representative set of test tasks
• Testing methods
• Transaction time studies
• Visualization studies
• Error rates and frequency of errors
• Satisfaction (attitudes, feelings)

7
Specific Methods

• Likert scale
• Semantic differential scale
• Quartile ratios

8
Likert scale

• A set of statements about the system
• Indicate degree of agreement
• on a scale 1-5 (or 1-7)
• 1 strongly disagree
• 2 partly disagree
• 3 neither agree nor disagree
• 4 partly agree
• 5 strongly agree

9
Semantic differential scale

• Two opposite terms along some dimension
• Indicate rating along the dimension
• Easy _ _ _ _ _ _ _ Difficult

10
Quartile ratios

• To measure the magnitude of individual
  differences
• A sorted range of observations
• Division of user performance data into four
  equally large sets
• The Q3/Q1 ratio indicates how much better the
  best 25 of the users are compared with the worst
  25

11
Quartile ratios

• Q3 indicates the level of performance where 25
  of the users are better and 75 are worse.
• Q1 indicates the level of perfomance where 25 of
  the users are worse and 75 are better
• 8 users 2,3,3,4,45,6 9 transactions pr. minute
• Buttom quartile will cut between second and third
  worst user level 3
• Top quartile will cut between second and third
  best user level 5.5
• The Q3/Q1 ratio 5.5/3 1.8
• Average for computer tasks is about 2

12
Design walk-through

• www.mcc.ruc.dk

13
Test Laboratory I

• Representative testgroup (three users) - Who ?
• Icon test
• Point and ask (testgroup)
• Draw a picture (all students)

14
Test Laboratory II

• Representative test tasks and transaction time
• Create a folder
• Upload a document and add a note
• Create a link, rate it as passable and then
  remove the description
• Start a discussion-thread and ask a question
• Configure user-access
• Use the project manager

15
Test Laboratory II

• Satisfaction questionnaire
• Decide on criterion for satisfaction (mean value
  at least ??)
• Summarize test results (overheads)
• ---
• New testgroup (eight users)
• Task test (chosen by students)
• Identify the Q3/Q1 ratio