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What is Usability?

What is Usability?. Usability is the measure of the quality of a user’s experience when interacting with a product or system. (Usability.gov, 2006) Usability is a quality attribute that assesses how easy user interfaces are to use. (Nielsen, 2003)

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What is Usability?

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  1. What is Usability? • Usability is the measure of the quality of a user’s experience when interacting with a product or system. (Usability.gov, 2006) • Usability is a quality attribute that assesses how easy user interfaces are to use. (Nielsen, 2003) • 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. (ISO standard 9241-11, 1998)

  2. What is Usability? • Ease of learning—How fast can a user learn to accomplish basic tasks? • Efficiency of use—How fast can an experienced user accomplish tasks? • Memorability—Can a user remember enough to use it effectively the next time? • Error frequency and severity—How often do users make errors, how serious are these errors, and how do users recover from these errors? • Subjective satisfaction—How much does the user like using the system?

  3. What is Usability Testing? • A usability test is a structured process used to explore the interaction between an objective participant and a proposed design • Paper and pencil (paper prototype) • Heuristic evaluation • Cognitive walkthrough • Usability Lab (functional prototype) • Formal testing with subjects

  4. What is Usability Testing? • Attributes common to most usability tests: • The goal is to improve a product. • Participants are real users. • The participants do real tasks. • Participants are formally observed. • The data are analyzed. • Recommendations for improvement are made. Dumas and Redish (1999)

  5. What is Usability? – Phases of a Usability Test • Design the Test • Prepare for the Test • Perform the Test • Process the Data

  6. Design the Test • Why: Define the Purpose • What: Define Your Concerns and Goals • What: Define the Tasks • What: Create the Scenarios • What: Define the Measurements • How: Define the Test Method

  7. Why: Purpose Statement What do you expect to gain from the test? What effect will the test results have on the project? How much of the design can be changed? Are there differences pf opinions between the team?

  8. Why: Purpose Statement E.g., We want to determine how easy Powerpoint 2007 is to learn for 2003 users. • What do you expect to gain from the test? • We expect to gain guidelines for improving the learnability of PPT 2007 • What effect will the test results have on the project? • Reorganize the layout of the interface. • How much of the design can be changed? • Offer new layout templates. • Are there differences of opinions between the team? • Most team members think that the layout should change to look more like 2003. Others think the menu should be renamed/reorganized.

  9. What: Concerns and Goals • What do we need to improve? • Look back at results of cognitive walkthroughs, heuristic evaluations, eval of paper prototype etc. • Concern: • The edit controls have been relocated • Goal: • Users will be able to paste with 2 clicks

  10. What: Tasks • What task should the user perform? • Task 1: Select a word, copy it, paste it next to the previous word • NO – this is artificial. Usability tests involve real tasks. • Better: Task 1: Reorder bullet points of a slide to match a flowchart

  11. What: Scenarios • A paragraph that tells a short story setting up the task. The user will read this. It should be: • Short • Complete • Unambiguous • Familiar

  12. What: Define Measurements • How do we measure usability of Powerpoint? • Quantitative • Time taken • Errors (?) • Number of incorrect click • Qualitative • interviews, questionnaires

  13. Design the Test • Where: Determine the Location of the Tests

  14. Why is Usability Testing Important? http://www.talltech.com/student/imos2k/finalproj/judy/research/index.htm#import

  15. Exercise: Design a study to evaluate the usability of the visual studio IDE • Step 1: Write a purpose statement (10 min) • What do you expect to gain from the test? • What effect will the test results have on the project? • How much of the design can be changed? • Are there differences of opinions between the team?

  16. Exercise: Design a study to evaluate the usability of the visual studio IDE • Step 2: Define concerns and goals (10 min) • What do we need to improve? • Identify 4 concerns • Define 4 corresponding goals for the user (hypotheses)

  17. Exercise: Design a study to evaluate the usability of the visual studio IDE • Step 3: Define tasks that will test each of your hypotheses (10 min) • What will you have participants do?

  18. Exercise: Design a study to evaluate the usability of the visual studio IDE • Step 4: Define scenarios (10 min) • A paragraph that tells a short story setting up the task. The user will read this. It should be: • Short • Complete • Unambiguous • Familiar

  19. Exercise: Design a study to evaluate the usability of the visual studio IDE • Step 5: Define Measurements (5 min) • List ways (quantitative and qualitative) ways that we will assess task performance (e.g., errors and time). • The results of these measurements will tell us whether our hypotheses can be accepted

  20. Design the Test • Who: Select Participants, Testers, and Observers

  21. Design the Test Participants should be real users You do not always need to test a great many users • The people you recruit should have the following basic characteristics: • Availability • Responsiveness • Objectivity

  22. Prepare for the Test • Writing Scripts • Greeting the Participant • Preliminary Interview • Providing Instructions • Monitoring the Test • Debriefing the Participant • Running a Pilot Test • Be organized • Be presentable

  23. Perform the Test • Test Phases • Pre-Test • Greet the participant. • Have the participant sign the informed consent form. • Have the participant fill out any pre-test questionnaire. • Proceed with scripts. • During the Test • Maintain a log or observation check list for each task. • Create a problem list to capture anything that is not covered by the check list. • Notate problems and jot down any hypotheses that occur to you about the problems.

  24. Perform the Test • Test Phases • Post-Test • Debrief the participant. • post-test questionnaire • verbal interview • Thank the participant and provide compensation. • Collect, summarize, and organize test data. • Reset the room for the next participant.

  25. Process the Data • Activities Performed on the Day of the Test • Collecting Data • Summarizing Data • Organizing the Material • Follow-Up Activities • Categorizing • Analyzing • Quantitative Data • Qualitative Data

  26. Process the Data • Documenting • Identify problems • Severity • Frequency • Errors of omission • Errors of commission • Prioritize problems • Theorize reasons • Theorize solutions • Identify successes • Identify areas of uncertainty

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