Usability Usability

Dr. Dania BilalDr. Dania Bilal

IS 582IS 582

Spring 2008Spring 2008

Usability Usability

• Measures multiple components of Measures multiple components of the user interfacethe user interface

• Addresses the relationships Addresses the relationships between system and its usersbetween system and its users

What Is Usability?What Is Usability?

• Bridges the gap between human and Bridges the gap between human and machinesmachines

• Measures system quality in relation to Measures system quality in relation to intended usersintended users

• Uses one or more methods to collect dataUses one or more methods to collect data– Each method is applied at appropriate time Each method is applied at appropriate time

of the design and development processof the design and development process

Importance of UsabilityImportance of Usability

• The sooner problems are found, the The sooner problems are found, the less expensive it is to fix themless expensive it is to fix them– Saves money by reducing designers’ Saves money by reducing designers’

time and product costtime and product cost

• Provides information about user Provides information about user experience and goalsexperience and goals

Importance of UsabilityImportance of Usability

• Learn aboutLearn about– users and their goals (affective and users and their goals (affective and

cognitive)cognitive)– Task difficultyTask difficulty– Success and failureSuccess and failure

• Generate requirements for Generate requirements for improving existing or creating new improving existing or creating new user-centered designuser-centered design

Usability AttributesUsability Attributes

• As described by NeilsenAs described by Neilsen– LearnabilityLearnability– EfficiencyEfficiency– MemorabilityMemorability– Errors & their severityErrors & their severity– Subjective satisfactionSubjective satisfaction

LearnabilityLearnability

• System must be easy to learn, System must be easy to learn, especially for novice usersespecially for novice users– Hard to learnHard to learn

• systems are usually designed for expert systems are usually designed for expert usersusers

– Learning curve for novice and expert Learning curve for novice and expert usersusers

EfficiencyEfficiency

• System should be efficient to use so System should be efficient to use so that once the user has that once the user has learned learned how how to use it, the user can achieve a high to use it, the user can achieve a high level of productivitylevel of productivity– Efficiency increases with learningEfficiency increases with learning– Efficiency difference from effectivenessEfficiency difference from effectiveness– Efficiency and effectiveness are Efficiency and effectiveness are

indications of successindications of success

MemorabilityMemorability

• System should be easy to rememberSystem should be easy to remember– No need to learn how to use system all No need to learn how to use system all

over again after a period of not using it. over again after a period of not using it. • System feature (searching, browsing, System feature (searching, browsing,

finding hidden features, etc.) are easy finding hidden features, etc.) are easy to remember in terms ofto remember in terms of– How (how to find them)How (how to find them)– What (what they are and what they do)What (what they are and what they do)– Where (where they are in the system)Where (where they are in the system)

Errors Errors

• System should have a low error rateSystem should have a low error rate• System should provide user with a System should provide user with a

recovery mechanism (how to correct recovery mechanism (how to correct a problem, what to do next, a problem, what to do next, suggestion for correcting a problem, suggestion for correcting a problem, etc.)etc.)

• Two types:Two types:– Minor errorsMinor errors– Major errorsMajor errors

Minor ErrorsMinor Errors

• Errors that did not greatly slow Errors that did not greatly slow down user’s interaction with the down user’s interaction with the system system

• User is able to recover from themUser is able to recover from them– through system feedbackthrough system feedback– through awareness of error madethrough awareness of error made– Not catastrophicNot catastrophic

Major ErrorsMajor Errors

• Difficult to recover from themDifficult to recover from them• Lead to faulty work if high in Lead to faulty work if high in

frequencyfrequency• May not be discovered by the userMay not be discovered by the user

– Errors can be catastrophicErrors can be catastrophic• Affect productivityAffect productivity• Cause negative affectCause negative affect• Cause abandoning systemCause abandoning system

Subjective SatisfactionSubjective Satisfaction

• System should be likeable by users System should be likeable by users (affective)(affective)

• Should meet user goalsShould meet user goals– SatisfactionSatisfaction– Positive experiencePositive experience– Sense of achievementSense of achievement– Want to user system againWant to user system again

AssumptionsAssumptions

• 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 helpSource: Nielsen, J. (1993). Usability Engineering. San Diego: Morgan Source: Nielsen, J. (1993). Usability Engineering. San Diego: Morgan

Kaufman.Kaufman.

Factors Influencing User Factors Influencing User Interaction with SystemInteraction with System

• Address the functionality of the Address the functionality of the system vis-à-vis:system vis-à-vis:– user needsuser needs– user tasksuser tasks– user information seeking user information seeking – user expectationsuser expectations– user cognitive processesuser cognitive processes– environmentenvironment

Usability AssessmentUsability Assessment

• Involves usersInvolves users• Users may perform tasks developed Users may perform tasks developed

by evaluator, or self-selected tasks, by evaluator, or self-selected tasks, or tasks in naturalistic settingor tasks in naturalistic setting

• Varies depending on goalVaries depending on goal• PerformedPerformed

– to uncover problems and correct themto uncover problems and correct them– To enhance the user experience by To enhance the user experience by

improving system improving system

Usability AssessmentUsability Assessment

• Performed Performed – before system is designedbefore system is designed

• How and why?How and why?

– during design processduring design process• How and why?How and why?

– after system releaseafter system release• How and why?How and why?

Usability MethodsUsability Methods

• One or a mix of methods can be used One or a mix of methods can be used • Depends on project usability goalsDepends on project usability goals

– BudgetBudget– Time constraintsTime constraints– Availability of experts for data collection and Availability of experts for data collection and

analysisanalysis– Complexity of system to be assessedComplexity of system to be assessed

Cognitive walkthrough Cognitive walkthrough methodmethod

• Focus is on how a user might achieve a Focus is on how a user might achieve a task and the problems he/she might task and the problems he/she might encounterencounter

• Experts play role of the userExperts play role of the user• Experts perform tasks given by Experts perform tasks given by

experimenter (project leader or observer)experimenter (project leader or observer)• Experts take notes about experience with Experts take notes about experience with

each taskseach tasks• Experimenter or observer takes notes as Experimenter or observer takes notes as

experts perform each taskexperts perform each task

Cognitive walkthrough Cognitive walkthrough methodmethod

• Experimenter/observer meets with experts prior Experimenter/observer meets with experts prior to data collection to decide on parts of system to data collection to decide on parts of system and other matters about the walkthrough and other matters about the walkthrough

• Experimenter:Experimenter:– prepares tasks (task are not disclosed to experts)prepares tasks (task are not disclosed to experts)– develops usability materialsdevelops usability materials– provides introduction about data collection. provides introduction about data collection. – decides on time and location of data collection decides on time and location of data collection

individually or in consultation with expertsindividually or in consultation with experts– schedules debriefing session to discuss collected dataschedules debriefing session to discuss collected data– Analyzes collected data, develops benchmarks by Analyzes collected data, develops benchmarks by

which to evaluate success on each task, and compiles which to evaluate success on each task, and compiles the final report.the final report.

Usability testing methodUsability testing method

• Actual users interact with systemActual users interact with system• Users perform tasks assigned by Users perform tasks assigned by

evaluator and/or selected by usersevaluator and/or selected by users• Users’ activities are observedUsers’ activities are observed

– Observation methodsObservation methods• Users may also be interviewedUsers may also be interviewed• Captured/collected data are coded, Captured/collected data are coded,

analyzed, and reportedanalyzed, and reported• Interview data are coded, analyzed, and Interview data are coded, analyzed, and

reportedreported

Usability testing method Usability testing method

• StagesStages– PreparationPreparation– IntroductionIntroduction– Data collection Data collection – DebriefingDebriefing

Neilsen, J. (1993). Usability Engineering. San Diego: Morgan Neilsen, J. (1993). Usability Engineering. San Diego: Morgan Kaufman.Kaufman.

Usability testing method: Usability testing method: PreparationPreparation

• Preparation for the experiment and Preparation for the experiment and data collectiondata collection– Location of test (e.g., room to be used)Location of test (e.g., room to be used)– System to be used, capturing software, System to be used, capturing software,

etc.etc.– Test materials, instructions, Test materials, instructions,

questionnaires to be completed, as questionnaires to be completed, as applicableapplicable

Usability testing method Usability testing method IntroductionIntroduction

• Explain purpose of testingExplain purpose of testing– Results to be for improving the Results to be for improving the

interfaceinterface

• Ensure user confidentialityEnsure user confidentiality– IRBIRB

• Collect data from usersCollect data from users

Usability testing method Usability testing method Introduction (cont’d.)Introduction (cont’d.)

• Encourage users to ask questions Encourage users to ask questions before and during experimentbefore and during experiment

• Provide users with necessary Provide users with necessary instructions to follow during data instructions to follow during data collectioncollection

Usability testing method: Usability testing method: Running the testRunning the test

• Don’t interact with user, unless Don’t interact with user, unless needed…needed…– Don’t give your personal opinionDon’t give your personal opinion– Don’t tell user how to perform certain Don’t tell user how to perform certain

taskstasks– Don’t distract user during the Don’t distract user during the

interaction interaction – Try to be unobtrusiveTry to be unobtrusive

Usability testing method: Usability testing method: DebriefingDebriefing

• User and/or data collector(s) is(are) User and/or data collector(s) is(are) debriefed after data are collecteddebriefed after data are collected

• Experimenter may follow up with Experimenter may follow up with users about interactionusers about interaction

• InterviewsInterviews• Survey questionnaireSurvey questionnaire• Focus groupFocus group

Usability testing method: Usability testing method: DebriefingDebriefing

• Experimenter ensures collected data Experimenter ensures collected data are labeled with user/participant nameare labeled with user/participant name

• Experimenter writes a brief, Experimenter writes a brief, preliminary report while events are still preliminary report while events are still fresh (can be in the form of notes)fresh (can be in the form of notes)

• Collected data are reviewed, coded, Collected data are reviewed, coded, analyzed, and interpretedanalyzed, and interpreted

• A report is generatedA report is generated

Usability method: Field Usability method: Field studystudy

• Observation of users performing tasks Observation of users performing tasks in everyday life in their own settingsin everyday life in their own settings

• Naturalistic Naturalistic • No tasks are assigned to usersNo tasks are assigned to users• Users’ interaction with system are Users’ interaction with system are

captured, coded, analyzed, captured, coded, analyzed, interpreted, and reported.interpreted, and reported.

• Interviews can be used in addition to Interviews can be used in addition to observationsobservations

Usability assessment: Usability assessment: Heuristic evaluation/testingHeuristic evaluation/testing• Evaluators interact with an interface Evaluators interact with an interface

and evaluate it based on predefined and evaluate it based on predefined heuristicsheuristics or guidelines or guidelines – See Neilsen’s ten heuristicsSee Neilsen’s ten heuristics

• Each evaluator generates a reportEach evaluator generates a report• Reports are aggregated and final Reports are aggregated and final

report is generatedreport is generated• An observer may be present An observer may be present

SourcesSources• http://http://www.usabilityfirst.comwww.usabilityfirst.com/methods/methods • http://http://

www.useit.com/papers/heuristic/heuristic_list.htmlwww.useit.com/papers/heuristic/heuristic_list.html (Neilsen’s usability heuristics)(Neilsen’s usability heuristics)

• http://http://www.useit.com/papers/heuristic/heuristic_evaluatiowww.useit.com/papers/heuristic/heuristic_evaluation.htmln.html (how to conduct a heuristic evaluation) (how to conduct a heuristic evaluation)

• http://http://www.uie.comwww.uie.com/articles/articles (collection of articles) (collection of articles)• http://http://www.uie.com/articles/usability_tests_learnwww.uie.com/articles/usability_tests_learn//

Learning about usability test (Jared Spool)Learning about usability test (Jared Spool)• http://http://

www.useit.com/papers/heuristic/severityrating.htmlwww.useit.com/papers/heuristic/severityrating.html (Severity rating)(Severity rating)

Project 2Project 2

• Review the description and Review the description and guidelines for Project 2. guidelines for Project 2.

• Begin initial plan for working on the Begin initial plan for working on the project by choosing the usability project by choosing the usability method you likemethod you like– Either choose heuristic evaluation or Either choose heuristic evaluation or

cognitive walkthroughcognitive walkthrough