1. Usability Dr. Dania Bilal IS 582 Spring 2008

2. Usability Measures multiple components of the user interfaceMeasures multiple components of the user interface Addresses the relationships between system and its usersAddresses the relationships between system and its users

3. What Is Usability? Bridges the gap between human and machinesBridges the gap between human and machines Measures system quality in relation to intended usersMeasures system quality in relation to intended users Uses one or more methods to collect dataUses one or more methods to collect data –Each method is applied at appropriate time of the design and development process

4. Importance of Usability The sooner problems are found, the less expensive it is to fix themThe sooner problems are found, the less expensive it is to fix them –Saves money by reducing designers’ time and product cost Provides information about user experience and goalsProvides information about user experience and goals

5. Importance of Usability Learn aboutLearn about –users and their goals (affective and cognitive) –Task difficulty –Success and failure Generate requirements for improving existing or creating new user-centered designGenerate requirements for improving existing or creating new user-centered design

6. Usability Attributes As described by NeilsenAs described by Neilsen –Learnability –Efficiency –Memorability –Errors & their severity –Subjective satisfaction

7. Learnability System must be easy to learn, especially for novice usersSystem must be easy to learn, especially for novice users –Hard to learn systems are usually designed for expert userssystems are usually designed for expert users –Learning curve for novice and expert users

8. Efficiency System should be efficient to use so that once the user has learned how to use it, the user can achieve a high level of productivitySystem should be efficient to use so that once the user has learned how to use it, the user can achieve a high level of productivity –Efficiency increases with learning –Efficiency difference from effectiveness –Efficiency and effectiveness are indications of success

9. Memorability System should be easy to rememberSystem should be easy to remember –No need to learn how to use system all over again after a period of not using it. System feature (searching, browsing, finding hidden features, etc.) are easy to remember in terms ofSystem feature (searching, browsing, finding hidden features, etc.) are easy to remember in terms of –How (how to find them) –What (what they are and what they do) –Where (where they are in the system)

10. Errors System should have a low error rateSystem should have a low error rate System should provide user with a recovery mechanism (how to correct a problem, what to do next, suggestion for correcting a problem, etc.)System should provide user with a recovery mechanism (how to correct a problem, what to do next, suggestion for correcting a problem, etc.) Two types:Two types: –Minor errors –Major errors

11. Minor Errors Errors that did not greatly slow down user’s interaction with the systemErrors that did not greatly slow down user’s interaction with the system User is able to recover from themUser is able to recover from them –through system feedback –through awareness of error made –Not catastrophic

12. Major Errors Difficult to recover from themDifficult to recover from them Lead to faulty work if high in frequencyLead to faulty work if high in frequency May not be discovered by the userMay not be discovered by the user –Errors can be catastrophic Affect productivityAffect productivity Cause negative affectCause negative affect Cause abandoning systemCause abandoning system

13. Subjective Satisfaction System should be likeable by users (affective)System should be likeable by users (affective) Should meet user goalsShould meet user goals –Satisfaction –Positive experience –Sense of achievement –Want to user system again

14. Assumptions The designer’s best guess is not good enoughThe designer’s best guess is not good enough The user is always rightThe user is always right The user is not always rightThe user is not always right Users are not designersUsers are not designers Designers are not usersDesigners are not users More features are not always betterMore features are not always better Minor interface details matterMinor interface details matter Online help does not really helpOnline help does not really help Source: Nielsen, J. (1993). Usability Engineering. San Diego: Morgan Kaufman.

15. Factors Influencing User Interaction with System Address the functionality of the system vis-à-vis:Address the functionality of the system vis-à-vis: –user needs –user tasks –user information seeking –user expectations –user cognitive processes –environment

16. Usability Assessment Involves usersInvolves users Users may perform tasks developed by evaluator, or self-selected tasks, or tasks in naturalistic settingUsers may perform tasks developed by evaluator, or self-selected tasks, or tasks in naturalistic setting Varies depending on goalVaries depending on goal PerformedPerformed –to uncover problems and correct them –To enhance the user experience by improving system

17. Usability Assessment PerformedPerformed –before system is designed How and why?How and why? –during design process How and why?How and why? –after system release How and why?How and why?

18. Usability Methods One or a mix of methods can be usedOne or a mix of methods can be used Depends on project usability goalsDepends on project usability goals –Budget –Time constraints –Availability of experts for data collection and analysis –Complexity of system to be assessed

19. Cognitive walkthrough method Focus is on how a user might achieve a task and the problems he/she might encounterFocus is on how a user might achieve a task and the problems he/she might encounter Experts play role of the userExperts play role of the user Experts perform tasks given by experimenter (project leader or observer)Experts perform tasks given by experimenter (project leader or observer) Experts take notes about experience with each tasksExperts take notes about experience with each tasks Experimenter or observer takes notes as experts perform each taskExperimenter or observer takes notes as experts perform each task

20. Cognitive walkthrough method Experimenter/observer meets with experts prior to data collection to decide on parts of system and other matters about the walkthroughExperimenter/observer meets with experts prior to data collection to decide on parts of system and other matters about the walkthrough Experimenter:Experimenter: –prepares tasks (task are not disclosed to experts) –develops usability materials –provides introduction about data collection. –decides on time and location of data collection individually or in consultation with experts –schedules debriefing session to discuss collected data –Analyzes collected data, develops benchmarks by which to evaluate success on each task, and compiles the final report.

21. Usability testing method Actual users interact with systemActual users interact with system Users perform tasks assigned by evaluator and/or selected by usersUsers perform tasks assigned by evaluator and/or selected by users Users’ activities are observedUsers’ activities are observed –Observation methods Users may also be interviewedUsers may also be interviewed Captured/collected data are coded, analyzed, and reportedCaptured/collected data are coded, analyzed, and reported Interview data are coded, analyzed, and reportedInterview data are coded, analyzed, and reported

22. Usability testing method StagesStages –Preparation –Introduction –Data collection –Debriefing Neilsen, J. (1993). Usability Engineering. San Diego: Morgan Kaufman.

23. Usability testing method: Preparation Preparation for the experiment and data collectionPreparation for the experiment and data collection –Location of test (e.g., room to be used) –System to be used, capturing software, etc. –Test materials, instructions, questionnaires to be completed, as applicable

24. Usability testing method Introduction Explain purpose of testingExplain purpose of testing –Results to be for improving the interface Ensure user confidentialityEnsure user confidentiality –IRB Collect data from usersCollect data from users

25. Usability testing method Introduction (cont’d.) Encourage users to ask questions before and during experimentEncourage users to ask questions before and during experiment Provide users with necessary instructions to follow during data collectionProvide users with necessary instructions to follow during data collection

26. Usability testing method: Running the test Don’t interact with user, unless needed…Don’t interact with user, unless needed… –Don’t give your personal opinion –Don’t tell user how to perform certain tasks –Don’t distract user during the interaction –Try to be unobtrusive

27. Usability testing method: Debriefing User and/or data collector(s) is(are) debriefed after data are collectedUser and/or data collector(s) is(are) debriefed after data are collected Experimenter may follow up with users about interactionExperimenter may follow up with users about interaction InterviewsInterviews Survey questionnaireSurvey questionnaire Focus groupFocus group

28. Usability testing method: Debriefing Experimenter ensures collected data are labeled with user/participant nameExperimenter ensures collected data are labeled with user/participant name Experimenter writes a brief, preliminary report while events are still fresh (can be in the form of notes)Experimenter writes a brief, preliminary report while events are still fresh (can be in the form of notes) Collected data are reviewed, coded, analyzed, and interpretedCollected data are reviewed, coded, analyzed, and interpreted A report is generatedA report is generated

29. Usability method: Field study Observation of users performing tasks in everyday life in their own settingsObservation of users performing tasks in everyday life in their own settings NaturalisticNaturalistic No tasks are assigned to usersNo tasks are assigned to users Users’ interaction with system are captured, coded, analyzed, interpreted, and reported.Users’ interaction with system are captured, coded, analyzed, interpreted, and reported. Interviews can be used in addition to observationsInterviews can be used in addition to observations

30. Usability assessment: Heuristic evaluation/testing Evaluators interact with an interface and evaluate it based on predefined heuristics or guidelinesEvaluators interact with an interface and evaluate it based on predefined heuristics or guidelines –See Neilsen’s ten heuristics Each evaluator generates a reportEach evaluator generates a report Reports are aggregated and final report is generatedReports are aggregated and final report is generated An observer may be presentAn observer may be present

31. Sources http://www.usabilityfirst.com/methodshttp://www.usabilityfirst.com/methodshttp://www.usabilityfirst.com/methods http://www.useit.com/papers/heuristic/heuristic_list. html (Neilsen’s usability heuristics)http://www.useit.com/papers/heuristic/heuristic_list. html (Neilsen’s usability heuristics)http://www.useit.com/papers/heuristic/heuristic_list. htmlhttp://www.useit.com/papers/heuristic/heuristic_list. html http://www.useit.com/papers/heuristic/heuristic_eval uation.html (how to conduct a heuristic evaluation)http://www.useit.com/papers/heuristic/heuristic_eval uation.html (how to conduct a heuristic evaluation)http://www.useit.com/papers/heuristic/heuristic_eval uation.htmlhttp://www.useit.com/papers/heuristic/heuristic_eval uation.html http://www.uie.com/articles (collection of articles)http://www.uie.com/articles (collection of articles)http://www.uie.com/articles http://www.uie.com/articles/usability_tests_learn/ Learning about usability test (Jared Spool)http://www.uie.com/articles/usability_tests_learn/ Learning about usability test (Jared Spool)http://www.uie.com/articles/usability_tests_learn/ http://www.useit.com/papers/heuristic/severityrating. html (Severity rating)http://www.useit.com/papers/heuristic/severityrating. html (Severity rating)http://www.useit.com/papers/heuristic/severityrating. htmlhttp://www.useit.com/papers/heuristic/severityrating. html

32. Project 2 Review the description and guidelines for Project 2.Review the description and guidelines for Project 2. Begin initial plan for working on the project by choosing the usability method you likeBegin initial plan for working on the project by choosing the usability method you like –Either choose heuristic evaluation or cognitive walkthrough