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Gathering Usability Data

Gathering Usability Data. Observing users & subjective data. Directing Sessions. Issues: Are you in same room or not? Single person session or pairs of people Objective data -- stay detached. Collecting Data. Data gathering Note-taking Audio and video tape Instrumented user interface

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Gathering Usability Data

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  1. Gathering Usability Data Observing users & subjective data

  2. Directing Sessions • Issues: • Are you in same room or not? • Single person session or pairs of people • Objective data -- stay detached PSYCH / CS 6750

  3. Collecting Data • Data gathering • Note-taking • Audio and video tape • Instrumented user interface • Post-experiment questions and interviews PSYCH / CS 6750

  4. Collecting Data • Identifying errors can be difficult • Qualitative techniques • Think-aloud - can be very helpful • Post-hoc verbal protocol - review video • Critical incident logging - positive & negative • Structured interviews - good questions • “What did you like best/least?” • “How would you change..?” PSYCH / CS 6750

  5. Observing Users • Not as easy as you think • One of the best ways to gather feedback about your interface • Watch, listen and learn as a person interacts with your system PSYCH / CS 6750

  6. Observation • Direct • In same room • Can be intrusive • Users aware of your presence • Only see it one time • May use 1-way mirror to reduce intrusiveness • Indirect • Video recording • Reduces intrusiveness, but doesn’t eliminate it • Cameras focused on screen, face & keyboard • Gives archival record, but can spend a lot of time reviewing it PSYCH / CS 6750

  7. Location • Observations may be • In lab - Maybe a specially built usability lab • Easier to control • Can have user complete set of tasks • In field • Watch their everyday actions • More realistic • Harder to control other factors PSYCH / CS 6750

  8. Challenge • In simple observation, you observe actions but don’t know what’s going on in their head • Often utilize some form of verbal protocol where users describe their thoughts PSYCH / CS 6750

  9. Verbal Protocol • One technique: Think-aloud • User describes verbally what s/he is thinking and doing • What they believe is happening • Why they take an action • What they are trying to do PSYCH / CS 6750

  10. Think Aloud • Very widely used, useful technique • Allows you to understand user’s thought processes better • Potential problems: • Can be awkward for participant • Thinking aloud can modify way user performs task PSYCH / CS 6750

  11. Teams • Another technique: Co-discovery learning (Constructive interation) • Join pairs of participants to work together • Use think aloud • Perhaps have one person be semi-expert (coach) and one be novice • More natural (like conversation) so removes some awkwardness of individual think aloud PSYCH / CS 6750

  12. Alternative • What if thinking aloud during session will be too disruptive? • Can use post-event protocol • User performs session, then watches video afterwards and describes what s/he was thinking • Sometimes difficult to recall • Opens up door of interpretation PSYCH / CS 6750

  13. Historical Record • In observing users, how do you capture events in the session for later analysis? • ? PSYCH / CS 6750

  14. Capturing a Session • 1. Paper & pencil • Can be slow • May miss things • Is definitely cheap and easy Task 1 Task 2 Task 3 … Time 10:00 10:03 10:08 10:22 S e S e PSYCH / CS 6750

  15. Capturing a Session • 2. Recording (audio and/or video) • Good for talk-aloud • Hard to tie to interface • Multiple cameras probably needed • Good, rich record of session • Can be intrusive • Can be painful to transcribe and analyze PSYCH / CS 6750

  16. Capturing a Session • 3. Software logging • Modify software to log user actions • Can give time-stamped key press or mouse event • Two problems: • Too low-level, want higher level events • Massive amount of data, need analysis tools PSYCH / CS 6750

  17. Issues • What if user gets stuck on a task? • You can ask • “What are you trying to do..?” • “What made you think..?” • “How would you like to perform..?” • “What would make this easier to accomplish..?” • Maybe offer hints • Can provide design ideas PSYCH / CS 6750

  18. Subjective Data • Satisfaction is an important factor in performance over time • Learning what people prefer is valuable data to gather PSYCH / CS 6750

  19. Methods • Ways of gathering subjective data • Questionnaires • Interviews • Booths (eg, trade show) • Call-in product hot-line • Field support workers • (Focus on first two) PSYCH / CS 6750

  20. Questionnaires • Preparation is expensive, but administration is cheap • Oral vs. written • Oral advs: Can ask follow-up questions • Oral disadvs: Costly, time-consuming • Forms can provide better quantitative data PSYCH / CS 6750

  21. Questionnaires • Issues • Only as good as questions you ask • Establish purpose of questionnaire • Don’t ask things that you will not use • Who is your audience? • How do you deliver and collect questionnaire? PSYCH / CS 6750

  22. Questionnaire Topic • Can gather demographic data and data about the interface being studied • Demographic data: • Age, gender • Task expertise • Motivation • Frequency of use • Education/literacy PSYCH / CS 6750

  23. Interface Data • Can gather data about • screen • graphic design • terminology • capabilities • learning • overall impression • ... PSYCH / CS 6750

  24. Question Format • Closed format • Answer restricted to a set of choices • Typically very quantifiable • Variety of styles PSYCH / CS 6750

  25. Closed Format • Likert Scale • Typical scale uses 5, 7 or 9 choices • Above that is hard to discern • Doing an odd number gives the neutral choice in the middle Characters on screen hard to read easy to read 1 2 3 4 5 6 7 PSYCH / CS 6750

  26. Other Styles Rank from 1 - Very helpful 2 - Ambivalent 3 - Not helpful 0 - Unused Which word processingsystems do you use? LaTeX Word ___ Tutorial ___ On-line help ___ Documentation FrameMaker WordPerfect PSYCH / CS 6750

  27. Closed Format • Advantages • Clarify alternatives • Easily quantifiable • Eliminate useless answer • Disadvantages • Must cover whole range • All should be equally likely • Don’t get interesting, “different” reactions PSYCH / CS 6750

  28. Open Format • Asks for unprompted opinions • Good for general, subjective information, but difficult to analyze rigorously • May help with design ideas • “Can you suggest improvements to this interface?” PSYCH / CS 6750

  29. Questionnaire Issues • Question specificity • “Do you have a computer?” • Language • Beware of terminology, jargon • Clarity • Leading questions • Can be phrased either positive or negative PSYCH / CS 6750

  30. Questionnaire Issues • Prestige bias • People answer a certain way because they want you to think that way about them • Embarrassing questions • Hypothetical questions • “Halo effect” • When estimate of one feature affects estimate of another (eg, intelligence/looks) PSYCH / CS 6750

  31. Deployment • Steps • Discuss questions among team • Administer verbally/written to a few people (pilot). Verbally query about thoughts on questions • Administer final test PSYCH / CS 6750

  32. Interviews • Get user’s viewpoint directly, but certainly a subjective view • Advantages: • Can vary level of detail as issue arises • Good for more exploratory type questions which may lead to helpful, constructive suggestions PSYCH / CS 6750

  33. Interviews • Disadvantages • Subjective view • Interviewer can bias the interview • User may not appropriately characterize usage • Time-consuming PSYCH / CS 6750

  34. Interview Process • How to • Plan a set of questions (provides for some consistency) • Don’t ask leading questions • “Did you think the use of an icon there was really good?” • Can be done in groups • Get consensus, get lively discussion going PSYCH / CS 6750

  35. Data Analysis • Simple analysis • Determine the means (time, # of errors, etc.) and compare with goal values (coming up…) • Determine • Why did the problems occur? • What were their causes? PSYCH / CS 6750

  36. Experimental Results • How does one know if an experiment’s results mean anything or confirm any beliefs? • Example: 20 people participated, 11 preferred interface A, 9 preferred interface B • What do you conclude? PSYCH / CS 6750

  37. Hypothesis Testing • In experiment, we set up a “null hypothesis” to check • Basically, it says that what occurred was simply because of chance • For example, any participant has an equal chance of preferring interface A over interface B PSYCH / CS 6750

  38. Hypothesis Testing • If probability result happened by chance is low, then your results are said to be “significant” • Statistical measures of significance levels • 0.05 often used • Less than 5% possibility it occurred by chance PSYCH / CS 6750

  39. Presentation Techniques Middle 50% Age low high Mean 0 20 Time in secs. PSYCH / CS 6750

  40. Upcoming • Audio • Web PSYCH / CS 6750

  41. Using the Results • How do you use the results of your evaluation? • How can you make your design better with this knowledge? PSYCH / CS 6750

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