Usability- användbarhet - Institutionen för Informatik · Entertainment Services Charlotte Wiberg Människa-Datorinteraktion - ett forskningsfält mellan teori och praktik. User!

Entertainment Services

Charlotte Wiberg

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. Charlotte Wiberg [email protected]


Charlotte Wiberg

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


Charlotte Wiberg

Människa-Datorinteraktion - ett forskningsfält mellan teori och praktik.

User

Worker Human Beings

UI

Tool Artifact

Understanding Informing

Designing Evaluation

User


Vanliga frågor

Charlotte Wiberg

• 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?


Usability

Charlotte Wiberg


Charlotte Wiberg

System Acceptability

Practical acceptability Social acceptability Cost Reliability Compatibility

Memorability

Etc.

USABILITY Utility

Learnability

Usefulness

Satisfaction

Efficiency

Errors

The context of usability(Nielsen, 1993)


Charlotte Wiberg

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.

•  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.


Charlotte Wiberg

Vad utvärdera?

•  Uppgift - task •  Aktivitet - activity •  Process - process

•  Task analysis kopplas ofta till usability


Utvärderingsmetoder för användbarhet

•  Dels grovt upp i: –  Empiriska utvärderingsmetoder –  Expertutvärderingsmetoder- inspektionsmetoder

Charlotte Wiberg

Entertainment Services Empiriska metoder

Charlotte Wiberg

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


Charlotte Wiberg

Usabilitylabb


Charlotte Wiberg

Usabilitylabb (forts)


Charlotte Wiberg

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

Expertutvärderingsmetoder (1)

Entertainment Services Expertutvärderingsmetoder (2)

Charlotte Wiberg

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.

Method

Characteristics of

evaluators

Number of evaluators

Goals of inspection

Entertainment Services Heuristic Evaluation (Nielsen, J)

Charlotte Wiberg

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.

Entertainment Services 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.

Charlotte Wiberg


Charlotte Wiberg

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.. )


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!

Charlotte Wiberg


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)


Charlotte Wiberg


Utvärdering i designprocessen


Charlotte Wiberg

Hur ser en designprocess ut?

Föranalys Analys Design Progr. Utv/Dok

Var kan eller vill vi utvärdera

användbarheten då?


Charlotte Wiberg

Designprocessen

Tid

Prototypens körbarhet

Kostnad för ändring av hittat fel

Föranalys Analys Design Progr. Utv/Dok

Expertmetodens lämplighet

Användar- testets

lämplighet


Charlotte Wiberg

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

Documents

Usability- användbarhet - Institutionen för Informatik · Entertainment Services Charlotte Wiberg Människa-Datorinteraktion - ett forskningsfält mellan teori och praktik. User!