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Usability Evaluation with Users. CMPT 281. Outline. Usability review Observational methods Interview methods Questionnaire methods. Usability. ISO 9241-11:

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outline
Outline
  • Usability review
  • Observational methods
  • Interview methods
  • Questionnaire methods
usability
Usability
  • ISO 9241-11:
    • The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency, and satisfaction, in a specified context of use
  • Efficiency
  • Effectiveness
  • Satisfaction
  • Context: user, task, environment
operationalizing usability
Operationalizing usability

How to assess usability criteria?

What measures?

What thresholds?

What is “usable enough?”

observational methods
Observational Methods
  • Simple observation
  • Think-aloud protocols
  • Retrospective think-aloud protocols
  • Co-discovery learning
  • Recording observations
simple observation
Simple Observation

User is given a task, and evaluator just watches the user

Problem: no insight into the user’s decision process or attitude

think aloud protocol
Think-aloud Protocol
  • Subjects are asked to say what they are thinking/doing:
    • What they believe is happening
    • What they are trying to do
    • Why they took an action
  • Gives insight into what the user is thinking
think aloud protocol1
Think-aloud Protocol
  • Problems:
    • Awkward/uncomfortable for subject (thinking aloud is not normal!)
    • “Thinking” about it may alter the way people perform their task
    • Hard to talk when they are concentrating on problem
  • Still the most widely used method in industry
retrospective think aloud
Retrospective Think-aloud
  • Problems with Think-aloud:
    • Awkward for subject (thinking aloud not normal!)
    • “Thinking” about it may alter the way people perform their task
    • Hard to talk when they are concentrating on problem
  • Solution: videotape the experience, perform a retrospective think-aloud
  • Has its own problems
    • Awkwardness of watching themselves on video
    • Awkwardness of reliving mistakes
    • Reflection of the experience rather than in context
co discovery learning
Co-discovery Learning
  • Two people work together on a task
    • Normal conversation between the two users is monitored
    • Removes awkwardness of think-aloud, more natural
    • Provides insights into thinking process of both users
field studies
Field Studies
  • Observe ‘in the field’ = natural environment
    • Sit and observe
    • Video records
    • Join the culture (ethnography)
field studies1
Field Studies
  • Observe ‘in the field’ = natural environment
    • Sit and observe
    • Video records
    • Join the culture (ethnography)
  • Requires that the system be fully deployed
  • Highest degree of realism
  • Can be highly specific to the particular setting
  • Can take a long time
recording observations
Recording Observations
  • Paper and pencil
    • primitive but cheap
    • evaluators record events, interpretations, and extraneous observations
    • evaluator seems disengaged
    • problem: writing is slow
      • prepared coding schemes can help; just tick off events
  • Audio recording
    • capture discussion (think aloud, co-discovery)
    • hard to synchronize streams (e.g., interface actions)
      • (expensive) tools exist to help
    • transcription is slow and difficult!
      • tools exist to help
recording observations1
Recording Observations
  • Video recording
    • can see what a user is doing
    • (good to use one camera/scan converter for screen + one for subject)
    • can be intrusive (at least initially)
    • analysis can be challenging
      • annotation is time consuming and dull
  • Companies often build “usability labs” with one-way mirrors, video cams, etc.
analyzing observation data
Analyzing Observation Data
  • Qualitative data:
    • interpreted to “tell a story”
  • Qualitative data:
    • categorized
  • Quantitative data:
    • presented as values, tables, charts, and graphs
    • often treated with statistical tests
  • How do you know which analysis is appropriate?
    • Depends on what you are using it for
querying users with interviews
Querying Users with Interviews
  • “conversations with a purpose”
  • excellent for pursuing specific issues
    • more interactive than observation: address specific issues of interest
    • more flexible than questionnaires: probe more deeply on interesting issues as they arise
  • problems
    • accounts are subjective
    • time consuming (to conduct and to analyze)
    • evaluator can bias the interview
    • prone to rationalization of events/thoughts by user
      • user’s reconstruction may be wrong
planning the interview
Planning the Interview
  • general
    • what is the purpose of the interview?
    • how many people? (breadth vs. depth)
    • length of interview & number of sessions
    • scheduling interviews (location, times, people)
    • will the interview be recorded? (audio, video; transcription)
  • avoid:
    • asking long questions
    • using compound sentences
    • using jargon
    • asking leading questions
    • … and generally be alert to unconscious biases.
interviews1
Interviews

control &

pre-determined questions

  • three main types:
    • open-ended / unstructured
    • semi-structured
    • structured
  • other categories (can include types above):
    • group
    • retrospective
unstructured interviews
Unstructured Interviews

So, difficult to use forquantitative study

  • most like a conversation, often go into depth
  • open questions
  • exploratory

key is to listen rather than talk: practice silence!

  • pros/cons:

+ rich data, things interviewer may not have considered

- easy to go off the rails

- time-consuming & difficult to analyze

- impossible to replicate

structured interviews
Structured Interviews

Think telephone survey

  • predetermined questions (like questionnaire, often with a flowchart)
  • closed questions
  • short, clearly worded questions
  • confirmatory
  • pros/cons:

+ replicable

- potentially important detail can be lost

better (cheaper) with a questionnaire?

semi structured interviews
Semi-structured Interviews

Between structured & unstructured

Uses elements of both

In usability studies, unstructured and semi-structured are the most common

group interviews focus group
Group Interviews (Focus Group)
  • 3 – 10 people interviewed at one time
  • usually has agenda, but may be structured/unstructured
  • skilled moderator critical!
  • usually recorded
  • pros/cons:

+ can accommodate diverse and sensitive issues

+ opinions developed within a social context

+ good way to locate “proto-users”: most articulate, imaginative participants can help later w/participatory design

- some interviewees may dominate

- expensive: usually pay participants + professional moderator

- people may not know what they think (or be afraid to express it)!

retrospective interview

Do you know why you never tried that option?

I didn’t see it. Why don’t you make it look like a button?

Retrospective Interview
  • post-test interview to clarify events that occurred during system use:

record what happened, replay it, and ask about it

  • pros/cons:

+ excellent for grounding apost-test interview

+ avoids erroneous reconstruction

+ users often offer concrete suggestions

- requires a second session

overview of an exploratory interview
Overview of an Exploratory Interview
  • explain purpose of the interview
    • allow time to get acquainted with the interviewee
    • provide understanding and background
  • enumerate activities
    • find out what the user does
  • explain work methods
    • find out how the user does things (skills and knowledge)
  • trace interconnections
    • determine other people and activities that are related
  • identify performance issues
    • explore current problems and impediments to success
things you uncover during interviews
Things You Uncover during Interviews
  • exceptions
    • lots of things people do are not “in the manual”
    • many jobs evolve to fit changing circumstances
    • much of this is not documented
    • many times “management” does not know about this
  • domain knowledge
    • most people know a lot about their jobs, and those they work with
  • terminology, common phrases, specific details
    • audio recording helps capture this
    • video recording helps provide body language
    • written notes can provide context, but not always details
querying users with questionnaires
Querying Users with Questionnaires
  • closed or open questions
  • get evidence of wide general opinion
  • or experiences after an experiment
  • pros/cons:

+ preparation expensive, but administration cheap

can reach a wide subject group (e.g. mail or email)

+ does not require presence of evaluator

+ results can be quantified

- risk: low response rate and/or low quality responses

questionnaires designing questions

Deeper issue: actions vs. beliefs vs. intentions

Questionnaires: Designing Questions
  • establish the purpose of the questionnaire:
    • what information is sought?
    • how would you analyze the results?
    • what would you do with your analysis?
  • determine the audience you want to reach
    • typical: random sample of between 50 and 1000 users of the product -- why a random sample?
  • test everything before sending it out:
      • test the wording
      • test the timing
      • test the validity
      • test the analysis
styles of questions open ended
Styles of Questions: Open-ended
  • asks for opinions
  • good for general subjective information
    • but difficult to analyze rigorously
  • E.g., “can you suggest any improvements to the interface?”
styles of questions closed
Styles of Questions: Closed

What does each answer mean??

  • restricts responses by supplying the choices for answers
  • can be easily analyzed …
  • but can still be hard to interpret, if questions / responses not well designed!

 alternative answers should be very specific

Do you use computers at work:

O often O sometimes O rarely

In your typical work day, do you use computers:

O over 4 hrs a day

O between 2 and 4 hrs daily

O between 1 and 2 hrs daily

O less than 1 hr a day

styles of questions scalar likert scale
Styles of Questions: Scalar - Likert Scale

Often multiple questions to triangulate underlying concept

Connect to affinity diagram

  • measure opinions, attitudes, and beliefs
  • ask user to judge a specific statement on a numeric scale
  • scale usually corresponds to agreement or disagreement with a statement

Characters on the computer screen are hard to read:

strongly agree strongly disagree

1 2 3 4 5

styles of questions scalar semantic differential scale
Styles of Questions: Scalar - Semantic Differential Scale
  • clear 1 2 3 4 5 confusing
  • attractive 1 2 3 4 5 ugly

explore a range of bipolar attitudes about a particular item

each pair of attitudes is represented as a pair of adjectives

WebCT is:

styles of questions multi choice
Styles of Questions: Multi-Choice

Will the latter work? Consider blanks.

  • respondent offered a choice of explicit responses

How do you most often get help with the system? (tick one)

O on-line manual

O paper manual

O ask a colleague

Which types of software have you used? (tick all that apply)

O word processor

O data base

O spreadsheet

O compiler

styles of questions ranked
Styles of Questions: Ranked
  • respondent places an ordering on items in a list
  • useful to indicate a user’s preferences
  • forced choice

Rank the usefulness of these methods of issuing a command

(1 most useful, 2 next most useful..., 0 if not used)

__2__ command line

__1__ menu selection

__3__ control key accelerator

styles of questions combining open ended closed questions
Stylesof Questions:Combining Open-ended & Closed Questions

the undo facility is great!

  • gets specific response, but allows room for user’s opinion

It is easy to recover from mistakes:

disagree agree comment:

1 2 3 4 5

herman miller aeron chair
Herman Miller – Aeron Chair
  • Comfort Likert
    • 1-10 (want 7.5)
    • Got 4.5
    • Eventually inched up to 8 before release
  • Aesthetics Likert
    • 1-10
    • Got 2-3 (never above 6!)
  • Usually a relationship between these two but it didn’t happen!
  • Focus Group
    • Check on pricing
    • Architects and designers liked
    • Facility managers and ergonomicists hated!
  • Entire design was *actually* user friendly
  • Where is this chair at today?
considerations
Considerations
  • Style of Questions
    • Open Ended
    • Closed
    • Choose one
    • Choose all that apply
    • Ratings (scale)
    • Rankings
  • Ease of Analysis
    • Poor
    • Depends
    • Easy
    • Somewhat easy*
    • Easy
    • Somewhat easy

*Note: Can’t really make a pie chart if the responses don’t add up to 100%

be considerate of your respondents
Be Considerate of Your Respondents
  • not just because it’s nice, but it works better.
  • questionnaire length (short is good):
    • think in terms of reasonable completion times
    • do not ask questions whose answers you will not use!
  • privacy invasions: be careful how / what you ask
  • motivation
    • why should the respondent bother?
    • usually need to offer something in return

… but be careful about introducing bias.

deployment issues
Deployment Issues
  • Online/email
    • html
    • tools
      • U of S survey tool
      • Survey Monkey
  • Choice impacts ease of analysis
    • 10000 responses? Go directly to database…
presenting questionnaire results1
Presenting questionnaire results

Choose one

Choose all that apply

summary questionnaires
Summary: Questionnaires
  • Establish purpose
  • Determine audience
  • Variety of administration methods(for different audiences)
  • Design questions:many kinds, depend on what you want to learn
  • Be considerate of your respondents
  • Motivate your respondents (without biasing them).