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Seng 5115 Spring 2011

Seng 5115 Spring 2011. Usability Testing. Usability Testing: A Systematic Look. The big picture. Why are you conducting the test? What are you going to learn? What will the results be used for? What kind of claims do you want to make?

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Seng 5115 Spring 2011

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  1. Seng 5115Spring 2011 Usability Testing

  2. Usability Testing: A Systematic Look

  3. The big picture • Why are you conducting the test? • What are you going to learn? • What will the results be used for? • What kind of claims do you want to make? • ROI: Your time and users’ are valuable

  4. Caveat: these columns are not carved in stone Two broad approaches

  5. Our focus so far (and today) More specifically, different methods • Controlled (laboratory) experiments • Field experiments • Field studies • Qualitative usability studies • Think aloud method

  6. What are you trying to learn? • Concrete, quantitative measures of usability • Time to learn a feature • Use time for specific tasks and users • Features used (or not)‏ • Error rates • Measures of user satisfaction • Comparison to prior/alternative versions, competitors • Results!

  7. What are you trying to learn (2)? • Qualitative experiences of usability • What will they use this thing for anyway? • Trouble spots in completing tasks • Features found / not found • Reactions to design elements/decisions • Learning users’ mental models • Why can’t those silly users do it? • Process!

  8. Exercise • For your prototype, brainstorm key things you would want to learn

  9. Picking users • Hopefully, real users • Variety • Authenticity: definitely not your group • Gosh, how many? • Key point: users’ time is valuable • Diminishing returns (especially formative)‏ • Recruitment

  10. Picking tasks • Tasks vs. play (exploration)‏ • Scripts for tasks • A lot like scenarios • When is the task over? • How long can tasks be? • What tasks should you choose?

  11. Which tasks? • Common tasks • Potentially troublesome tasks • Aspects of the design with many options • Tasks your prototype supports! • Horizontal vs. vertical prototyping • The Wizard of Oz

  12. What data to collect? • Observations, notes • Videotape? • Pretests • To gauge/control for experience level • Questionnaires • Multiple choice vs. open-ended questions • Process data

  13. Think aloud method • User asked to think aloud • ask questions (they won’t be answered) • explain decisions, identify confusion • Very useful for understanding

  14. Setting up the test environment

  15. Setting up the environment • “Natural” use scenario • Eliminate distractions • (unless distractions are part of the test!)‏ • Space between user and experimenter • Facilities for observers and data collection

  16. Roles • Experimenter • Observer / Data Collector

  17. The experimenter • Oversees the testing process • Makes sure setup is ready • Welcomes users • Conducts test activities • Debriefs subjects • Better to not collect data • Let observers do this

  18. Experimenters: very important • Practice! • Be consistent • Don’t “help” or interfere with tests • Very tempting… • But keep ethics in mind • Be aware that testing can affect you

  19. Pilot study: very important • Find obvious mistakes • Hopefully, Cognitive Walkthrough and Heuristic Evaluation helped here • Get practice running tests • Check that tasks are realistic • Gain confidence in data collection • Pilot study likely to change test plan

  20. Running a test with one user • Preparation • Introduction • Scripts • Debriefing

  21. Running: Preparation • Room ready? • Equipment ready? • Interface in the start state? • Observers present? • One experimenter, several observers • Other needed materials available?

  22. Running: Introduction • Evaluating the interface, not the user • No personal stake • Confidentiality reminder -- system,results • Voluntary participation • Welcome to ask questions • Specific instructions • Any questions?

  23. Running: Scripts • Introduce each task • Go over task with subject • Ask for questions • Refrain from interacting with the subject • “Help”ing doesn’t • Prompt for thinking aloud, if needed • Watch for stuckness: wait, hint, skip, fail

  24. Running: Debriefing • Administer questionnaires • Ask follow-up questions • General discussion • Any other comments? • Thank them! • Team debrief?

  25. Interpreting the data • Some way of prioritizing • Severity • Number of observers who record problem • Ease of fixing • Summarizing the results • A report • More on this later • Note: Keep a design focus! • Or you may be analyzing for months….

  26. General Guidelines • Always have a pilot study • Get professional help for big studies • In general, it is better if you aren’t there • too much bias • subtle clues (the counting horse)‏ • stay behind one-way glass • (but, realistically….)‏

  27. Test Plan Checklist, 1 • Goal of the test? • Specific questions you want to answer? • Who will be the experimenter? • Who are the users going to be? • How many users are needed? • What kind of instruction will users be given? • What tasks will you ask the users to perform? • What criteria will be used to determine the end of each task?

  28. A Test Plan Checklist, 2 • What aids will be made available to users? • To what extent will the experimenter be allowed to help the users? • What data is going to be collected and how will it be analyzed? • What is the criterion for judging the interface a success?

  29. A Test Plan Checklist, 3 • Where and when will the evaluation be done? • How long will the evaluation take? • What computer support? • What software? • Initial state of the system? • Are there any system/network load requirements?

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