Usability- användbarhet

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Alexandra Nyström
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1 Usability- användbarhet Tekniker, metoder och annat vi måste känna till för att kunna använda oss av usability som ett framgångsrecept i design av IT & digitala medier. cwiberg@informatik.umu.se

2 Veckans agenda Usability vad är det? Definitioner på användbarhet. Utvärdering i stort inom HCI & ID - vad har vi för andra möjligheter? Utvärderingsmetoder två huvudspår Empiriska utvärderingsmetoder Expertmetoder Metodologiska avvägningar Utvärdering i relation till designprocessen

3 Människa-Datorinteraktion - ett forskningsfält mellan teori och praktik. Understanding Informing Human Beings Worker User Artifact Tool UI Evaluation Designing

4 Vanliga frågor Hur ser en professionell målgruppsanalys/användartest ut? Hur gör man en sån test? -personliga intervjuer? -kvalitets test? -kvantitetstest? Vilka fel kan man göra? Hur använder man sig av resultatet? Hur presenterar man sitt resultat? När bör man göra en sån här test? När bör man inte göra en sån här test?

5 Usability

6 The context Entertainment of Services usability(nielsen, 1993) System Acceptability Practical acceptability Social acceptability Cost Reliability Compatibility Etc. Usefulness Utility USABILITY Learnability Efficiency Memorability Errors Satisfaction

7 Usability aspects (Nielsen, 1993) Learnability: The system should be easy to learn so that the user can rapidly start getting some work done with the system. Efficiency: The system should be efficient to use, so that once the user has learned the system, a high level of productivity is possible. Memorability: The system should be easy to remember, so that the casual user is able to return to the system after some period of not having used it, without having to learn everything all over again. Entertainment Services Errors: The system should have a low error rate, so that users make few errors during the use of the system, and so that if they do make errors they can easily recover from them. Further, catastrophic errors must not occur. Satisfaction: The system should be pleasant to use so that users are subjectively satisfied when using it; they like it.

8 Vad utvärdera? Uppgift - task Aktivitet - activity Process - process Task analysis kopplas ofta till usability

9 Utvärderingsmetoder för användbarhet Dels grovt upp i: Empiriska utvärderingsmetoder Expertutvärderingsmetoder- inspektionsmetoder

10 Empiriska metoder Entertainment Services Method Measures Generated data Think-aloud (or verbal) protocol Captured events from usage situations; problems, expectations etc. Record of cognitive processes of users in system usage Use data collection Number of errors, types of errors, time to complete task Record of statistics for errors, listings of types of occurring errors, time statistics Clinical experiments Eye gaze, heart rate, skin color, body heat Statistics for measured clinical aspects Surveys and Questionnaires Accuracy regarding memory, learning etc. Record of answers quantitative or qualitative Interviews General information from users. Structured or unstructured. Record of answers - qualitative

11 Usabilitylabb

12 Usabilitylabb (forts)

13 Expertutvärderingsmetoder (1) Entertainment Services Method Characteristics of evaluators Number of evaluators Goals of inspection Heuristic evaluation Usability experts One Judge whether each element in interface follows heuristics Cognitive Walkthrough Cognitive Psychologists One Predictions of user behavior regarding learning Formal usability inspections One or group Combines Heuristic Ev. with Cog. Walkthrough Design (or pluralistic) Walkthroughs Users, developers and Human Factor HCI experts One or group Walkthrough of each dialogue element by using scenarios

14 Expertutvärderingsmetoder Entertainment (2) Services Method Characteristics of evaluators Number of evaluators Goals of inspection Feature inspection Inspection of sequences of (complicated) features Consistency inspection (External) designers Group Comparison of different designs to check consistency Standard inspections Expert in (specific) standard(s) One Inspection of interface for compliance with standard(s) Theory-based reviews Experts in each method One Discover problems on a micro-level.

15 Heuristic Evaluation Entertainment (Nielsen, J) Services 1. Visability of system status The system should always keep users informed about what is going on, through appropriate feedback within reasonable time. 2. Match between system and real world. The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order. 3. User control and freedom Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo. 4. Consistency and standards Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions. 5. Error prevention Even better than good error messages is a careful design, which prevents a problem from occurring in the first place.

16 Heuristic Evaluation (2) 6. Recognition rather than recall Make objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate. 7. Flexibility and efficiency of use Accelerators -- unseen by the novice user -- may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions. 8. Aesthetic and minimalist design Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility. 9. Help users recognize, diagnose and recover from errors. Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution. 10.Help and documentation Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large.

17 Metodologiska avvägningar Design - implementation, var i process Laboratorium - fältstudier Subjektiv - objektiv, grad av tolkning Kvalitativ - kvantitativ mätning Tidpunkt för svar Grad av involvering (intervention) Resurser för utvärdering (labb,speglar.. )

18 Från usability till user experience (UX) 2004 en klar skillnad på traditionell användbarhet och UX Idag vill vissa säga att det är samma sak för att vinna mark allt är usability! allt är UX Samma problem kvarstår dock oberoende vad vi kallar aspekten så har vi en flora av metoder och mått som passar mer eller mindre bra. Viktigt att ha koll på Jordans trappa (User Needs) Viktigt att skilja på typer av fel i relation till denna Viktigt att kunna skilja svåra (severe) fel från mindre svåra fel Detta avgörs från syftet med artefakten MEN om den är oklar blir er uppgift att säga något om usability och/eller UX oklar! Viktigt att informera/lära kunden om detta!

19 Övningsuppgift: Jobba tillsammans 2 informationsåtkomstwebbplatser Skriv ner identifierade usabilityproblem Hittar ni andra än sådant som inryms inom heuristikerna? 45 minuter (max) Redovisa för lärare samt diskussion (15 min)

21 Utvärdering i designprocessen

22 Hur ser en designprocess ut? Föranalys Analys Design Progr. Utv/Dok Var kan eller vill vi utvärdera användbarheten då?

23 Designprocessen Kostnad för ändring av hittat fel Prototypens körbarhet Användartestets lämplighet Expertmetodens lämplighet Tid Föranalys Analys Design Progr. Utv/Dok

24 Iterativ design Cykliskt tänkande där utvärdering återfinns i varje fas. Olika typer av utvärderingar används usability, utility, debugging mm Iterationerna kan vara av olika längd Kan vara kostsamt i alla fall på kort sikt Återfinns (tyvärr) mest inom forskningsvärlden

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