Användbarhet - usabilityAnvändbarhet - usability

Vad är användbarhet, hur testar vi Vad är användbarhet, hur testar vi det och vilka är måtten. Vad kan det och vilka är måtten. Vad kan

man sedan ha resultaten till?man sedan ha resultaten till?

Usability

System Acceptability

Practical acceptability Social acceptabilityCostReliabilityCompatibility

Memorability

Etc.

USABILITYUtility

Learnability

Usefulness

Satisfaction

Efficiency

Errors

The context of usability(Nielsen,

1993)

Usabilityaspekter (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.

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.

Utvärderingsmetoder för användbarhet

Dels grovt upp i:

• Empiriska utvärderingsmetoder

• Expertutvärderingsmetoder- inspektionsmetoder

Empiriska metoder

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

Usabilitylabb

Usabilitylabb (forts)

Expertutvärderingsmetoder

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

Feature inspection

    Inspection of sequences of (complicated) features

Heuristic Evaluation 1.      Visability of system statusThe 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 freedomUsers 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 standardsUsers should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions. 5.     Error preventionEven better than good error messages is a careful design, which prevents a problem from occurring in the first place. 6.      Recognition rather than recallMake 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 useAccelerators -- 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.

Usabilityaspekterna i relation till metoder och mått

Hur utvärdera?

Design - implementation, var i processLaboratorium - fältstudierSubjektiv - objektiv, grad av tolkningKvalitativ - kvantitativ mätningTidpunkt för svarGrad av involvering (intervention)Resurser för utvärdering (labb,speglar.. )

Användbarhet och upplevelser

• Charlotte Wiberg

Usability användbarhet – vad är det?• Förståelse

• Lärbarhet

• Effektivitet

• Antal fel

• ’USER SATISFACTION

• Traditionella usabilitystudier

• Användarstudier

• Tidsstudier

• Heuristiker

• Upplevelse

• Estetik

• Attityd

• Kul

• Hur mäter vi det då?

• Eye tracking

• Puls

• Intervjuer

• ..

• …

Upplevelser?

• Funktionalitet – användbarhet – upplevelser• Holistisk egenskap• Teorier?• Kan teorierna hjälpa oss bilda bas för att

avgöra om bra/dåliga upplevelser?• Vad utvärderas – gränssnittet eller

användaren?

Avhandlingen - fokus

• EWS – entertainment web sites• Upplevelser – underhållning – EWS• Kan traditionella metoder användas vid

utvärdering av EWS?• Resultat: Ja.. Med viss modifikation kan

både traditionella Emp metoder och expertmetoder användas – se modifikationer.

Resultat

• Specifika heuristiker för Heuristisk utvärdering

• Guidelines för empirisk utvärdering