• Aucun résultat trouvé

C ONCEPTION TILISATEUR POUR C ENTRÉE LE W U EB

N/A
N/A
Protected

Academic year: 2022

Partager "C ONCEPTION TILISATEUR POUR C ENTRÉE LE W U EB"

Copied!
166
0
0

Texte intégral

(1)

C ONCEPTION C ENTRÉE

U TILISATEUR POUR LE W EB

MNT

25 octobre 2012

James Eagan <james.eagan@telecom-paristech.fr>

(2)

J AMES E AGAN  

MAÎTRE DE CONFÉRENCES EN INTERACTION HOMME-MACHINE

Maître de conférences en IHM à Télécom ParisTech

Ph. D. en Informatique, Georgia Institute of Technology

Recherche en Visualisation d’Information, Interaction Multi- surface

(3)
(4)

W HY D O W E C ARE ?

(5)
(6)
(7)

IBM

1999 : « Most popular feature was ... search ... people couldn’t figure out how to navigate the site »

« The 2nd most popular feature was the help button, because the search technology was so ineffective. »

Après re-conception du site centrée utilisateur :

Utilisation du bouton « help » a baissé 84 %

Ventes ont augmenté 400 %

[ New York Times, 30 août 1999 ]

(8)

O UTLINE

Principes de l’utilisabilité

Perception

Comprendre l’utilisateur

Analyse de tâches

Prototypage

Evaluation & Expériences Utilisateur

(9)

U SABILITY P RINCIPLES

(10)

U SABILITY P RINCIPLES

Many different kinds

No cookbooks, checklists, magic recipes

Shneiderman, Designing the User Interface

Dix, Finlay, Abowd, Beale, Human-Computer Interaction

(11)

U SABILITY P RINCIPLES

Learnability

Support for learning for users of all levels

Flexibility

Multiple ways for performing tasks

Robustness

Support recovery

(12)

L EARNABILITY

Ease with which new users can begin effective interaction

Performance improvement from session to session

Principles

Predictability, Synthesizability, Familiarity, Generalizability, and Consistency

(13)

C HUNKING

(14)

P REDICTABILITY

I think that this action will do…

Operation visibility – can see all available actions

e.g. menus versus command-line

Grayed menu items

(15)

P REDICTABILITY

vs.

(16)

F LEXIBILITY

Minimize modality, Multithreading, Task Migratability, Substitutivity, Customizability

(17)

R OBUSTNESS

Observability

Recoverability

Responsiveness

Task Conformance

(18)

O BSERVABILITY

(19)

O BSERVABILITY

(20)

ENTONNOIR DE PROCESSUS

Version simplifiée de l’interface

Adaptée pour focaliser sur le processus impliqué

Évite de distractions, confusion

(21)
(22)
(23)

R ECOGNITION OVER R ECALL

(24)

M ODÈLES M ENTAUX

La représentation mentale de l’utilisateur du système

Sa perception de comment marche le système

(25)

D ON N ORMAN

Design of Everyday Things

(26)

I NTERFACE DUN F RIGO

(27)

M ODÈLE DUN F RIGO

(28)

M ODÈLE DUN F RIGO

(29)

I NTERFACE DUN F RIGO

(30)

M AKE C ONTROLS L OOK & F EEL

D IFFERENT

(31)

P ARADOX OF C HOICE

(32)
(33)

I NVOKE S CARCITY

If it costs a lot, it must be good!

Only two left in this size!

(34)
(35)
(36)
(37)

[ Source : James Hudson, PayPal ]

(38)

[ Source : James Hudson, PayPal ]

(39)

[ Source : James Hudson, PayPal ]

(40)

33 % conversion

66 % conversion

[ Source : James Hudson, PayPal ]

(41)

[ Source : James Hudson, PayPal ]

(42)

Conception Centrée Utilisateur

(43)

W HY D O W E C ARE ?

Même si ce ne serait pas nous qui font tout ça, il faut pouvoir le comprendre, qu’est-ce qui est important, et comment le

communiquer avec les experts

Fondamentalement une question de relations

Vous et vos

Designers, ingénieurs, experts d’XU, chercheurs, marketing,

(44)

Conception

Prototypage

Evaluation

(45)

Qui est l’utilisateur ?

Quels sont ses besoins ?

Quel est le contexte d’utilisation ?

Sociale, dans l’organisme, environnement

Pourquoi veut-il faire ces tâches ?

(46)

MYTHES DE LA CONCEPTION CENTRÉE UTILISATEUR

Mythe 1 : Un bon design est juste du bon sens

Pourquoi y a-t-il autant de mauvais sites ?

Mythe 2 : Seulement les experts peuvent créer des bons designs

Les experts sont plus rapides, mais tout le monde peut comprendre la CCU

(47)

Mythe 3 : On peut toujours changer l’interface avant de déployer

Ça suppose que le site comporte déjà de la bonne fonctionnalité est des bonnes pratiques de

développement

Mythe 4 : Un bon design prend trop de temps/est trop cher

CCU aide à trouver des problèmes tôt dans le processus, réduisant le coût et le temps de

développement

(48)

Mythe 5 : Un bon design n’est que des jolies images

N’est qu’une part de l’identité de l’organisme

Mythe 6 : Suivre des guidelines suffit pour créer un bon design

Guidelines s’occupe seulement de

l'implémentation, pas de la fonctionnalité et son

organisation

(49)

Mythe 7 : Le client peut toujours se servir de la doc/aide

Si le client regarde la doc, il est déjà énervé !

Mythe 8 : Market Research suffit pour comprendre les besoins du client

Montre ce que le client dit, pas ce qu’il fait.

(50)

Mythe 9 : l’assurance de qualité/tests peuvent montrer si un site marche bien

Le testing montre seulement si le site

corresponde à la spécification, pas ce qui arrive

avec des vrais clients

(51)

Clients :

• Rôles (Qui) • Tâches (Quoi) • Contexte

Marketing : • Priorités • Messages Technologie : • Produits

• Architecture Design :

• L’état de l’art

Définition du design

• Description de problèmes

• Utilisateurs ciblés

• Tâches utilisateurs

Processus de Développement

Design

Discovery Design

Exploration Evaluation Exécution

Clients, Produits, Entreprise, Marketing

Clients, Produits,

Entreprise, Marketing Clients, Produits, Entreprise, Marketing

Storyboards

Proposal

• Démos

• Prototypes légers Itération

Spécification

• Design raffiné

• Description du design

• Réaliser le design

• Évaluation avec utilisateurs

[ Source : Sara Redpath, IBM ; Thyra Trauch, Tivoli ]

(52)

ITÉRATION

Design

Prototype

Évaluation

À chaque étape !

(53)

DESIGN

Un bon design dépend des besoins

Le but de l’objet

Pas comment c’est implémenté

e.g., téléphone mobile moins important que « app mobile »

(54)

DESIGN = REPRÉSENTATION

Pour un interface, ça peut être :

sketches ou storyboards

outline / diagrammes de flux

prototypes exécutables

(55)

Schématiques

Storyboards

Mockups

(56)

E VALUATION

(57)

L ABORATOIRE D ’U TILISABILITÉ

(58)

S ALLE D ’O BSERVATION

Grand champ de vision, glace uni-directionnel,

isolation de lumière et son

Portes situées tel que le

participant ne peut pas les voire en entrant dans la salle d’observation

(59)

S ALLE D ’O BSERVATION

Trois écrans pour voir le participant, l’écran du

participant, et les deux à la fois

Confortable pour plusieurs observateurs

DVD-R pour enregistrer la séance

(60)

S ALLE DU P ARTICIPANT

Se ressemble à un bureau normale

Caméra haute-

résolution, contrôlable à distance, placée

discrètement dans le coin

Micro

(61)
(62)

L A T HÉORIE DE G RANDE U NIFICATION

Qui est {l’utilisateur, le client, le sujet, …} ?

Astuce : Il y en a probablement plusieurs

Qu’est-ce qu’il ou elle essaye de faire ?

Comment peut-on l’aider à le faire ? (Et gagner quelques €/$/

¥ en le faisant.)

L’interface, réussit-elle ces buts ?

(63)

K NOW T HY U SER

You are not your user

Who are your stakeholders?

Travel system: employee, manager, auditor

What is the user’s goal?

How is success defined?

What are the constraints? Real-world, technical, political?

User characteristics

(64)

R EAL -W ORLD C ONSTRAINTS

Time to market

Cost/effort to design & implement

Size/footprint/weight/price/power

Computer power/memory

Consistency with product line/brand image

Backward compatibility

Differentiation from competitive products

(65)

H OW TO U NDERSTAND THE U SER

Gather data

Interviews, observation, surveys & questionnaires, documentation, immersion

Organize data

Notes, cards, brainstorming, computer tools

Represent data

Lists, outlines, matrices

Narratives, Scenarios

Hierarchies, Networks, Flow Charts

(66)

W HAT TO G ATHER

Three key components in how people work

Activities

Artifacts

Relations

Not just computer system oriented!

The context matters!

Office: papers, whiteboards, …

Phone calls: address book, note pad, dialer, …

(67)

F OCUS ON O BSERVABLE B EHAVIORS

What are the practices, methods, steps, objects, …, used?

Learn what users do, why they do it, how, they do it, when they do it, with what tools or people they do it

Your new system may change some of this, especially how

Understanding the how and the why is what leads to deeper knowledge and insights

(68)

D ATA G ATHERING

Tasks & Substasks

Physical

Cognitive

Communication

Conditions under which these are done

Results/outcomes of tasks

(69)

T ASK R EQUIREMENTS

Requirements to perform task

Information

Communication with others

Equipment

Must include Should include Could include Exclude

(70)

S OME D ATA G ATHERING M ETHODS

Observation & Think-aloud

Cooperative Evaluation

Interviews

Questionnaires & Surveys

Focus Groups

Study Documentation

Competitive Product Analysis

Ethnography

(71)

I NTERPRETIVE A NALYSIS

Controlled Experiments: formal & objective

Interpretive Analysis: more subjective

Concerned with humans, so no objective reality

Sociological approach

(72)

C ONTROLLED E XPERIMENTS

Great for objective performance

But:

Lab is not the real world

Can’t control all the variables

Context matters

Tasks are short, artificial

(73)

I NTERPRETIVE A NALYSIS M ETHODS

Field studies, contextual inquiry, ethnography

Inspired by anthropology (€¥$)

Interviews

Philosophy:

Formal environment of controlled study is artificial, so

Get into user’s environment

Interpretation is primary over data

(74)

O BJECTIVES

Understand the user

What are his or her goals & values?

Individual’s or group’s interactions within a culture

Make tacit domain knowledge explicit

Be unbiased

For UI designers: improve system by finding existing problems

(75)

T ECHNIQUES

In-person observation

Audio/video recording

Interviews

“Wallow in the data”

(76)

O BSERVATION IS K EY

Carefully observe everything about the users and their environment

Think of describing it to someone who has never seen this activity before

What users say is important, but also non-verbal details

(77)

O BSERVATIONS

Things of interest to the evaluator

Structure & language used in work (domain vocabulary)

Individual & group actions

Work culture

Explicit & implicit aspects of work

Example: Office environment

Business practices, rooms, artifacts, work standards, relationships between workers, managers, …

(78)

I NTERVIEWS

Have a question plan, but keep interview open

Be specific

Create interpretations together with users

Be sure to use their terminology

At the end, ask if there’s anything else you should have asked

Record interviews

(79)

S TEPS

1. Preparation

Understand the organizational context

Familiarize yourself with system and its history

Set initial goals and prepare questions

Gain access and permission to observe & interview

(80)

D URING I NTERVIEWS

Establish rapport with users

Observe/interview users in workplace and collect all different forms of data

Follow any leads that emerge from visits

Record the visits

(81)

A NALYSIS

Compile the data in numerical, textual, and multimedia databases

Quantify data and compile statistics

Reduce and interpret data

Refine goals and process used

(82)

R EPORTING

Consider different audiences and goals

Prepare a report and present findings

(83)

A FFINITY D IAGRAM

Useful technique for qualitative data analysis

Write each observation/quote on a slip of paper

Put it on a board/wall

Coalesce items that have affinity

Give names/colors to groups

Continue making subgroups

May yield a hierarchy of groups

(84)
(85)
(86)
(87)

W HY IS THIS U SEFUL ?

Can help gain a rich and true assessment of user needs

Helps to define requirements

Uncovers true nature of user’s needs

Discover things that are outside job description, documentation

Allows you to put yourself in the role of an end-user

Open-ended and unbiased nature promotes discovery

(88)

T YPES OF F INDINGS

Qualitative

Observe trends, habits, patterns, …

Quantitative

How often was something done, what percent of the time did something occur, how many errors, …

(89)

D RAWBACKS

Takes a lot of time

Scale : small numbers

Qualitative results are subjective and difficult to generalize

Acquired skill

Identifying and extracting meaningful and “interesting” things is challenging

(90)

A LTERNATIVE : O BSERVATIONS

Observe user performing activity of interest to you

Record audio/video/screen (with permission)

(91)

T HINK -A LOUD O BSERVATIONS

Observe user performing activity of interest to you

Record audio/video/screen (with permission)

Encourage user to verbalize what they are thinking

Not everyone is good at this

Hard to keep it up for long; need breaks

(92)

C OOPERATIVE E VALUATION

User is viewed as a collaborator in evaluation, not a subject

“Friendly approach”

Relaxed version of think-aloud

Evaluator and participant can ask each other questions

(93)

T HINK - ALOUD & C OOP E VAL

Help to detect errors early in a prototype

Experimenter uses tasks, also talks to participant throughout, asks questions

Have a debriefing session at the end

(94)

I NTERVIEWS

Structured — “Just the facts”

Efficient

Training: interview process

Unstructured — A conversation

Inefficient

Training: process + domain knowledge

(95)

S EMI -S TRUCTURED I NTERVIEWS

Start with focused questions, move to open-ended discussion

Good balance, often appropriate

Training: process + domain knowledge

(96)

S EMI - STRUCTURED I NTERVIEW Q UESTIONS

Pre-determine data of interest — know why you are asking questions, don’t waste time

Plan for effective question types

How do you perform task x?

Why do you perform task x?

Under what conditions do you perform task x?

What do you do before you perform…?

What information do you need to…?

Whom do you need to communicate with …?

What do you use to…?

What happens after you…?

What is the result or consequence of…?

What is the result or consequence of NOT…?

See Gordon & Gill, 1992; Graesser, Lang, & Elofson, 1987

(97)

T YPICAL O PEN - ENDED Q UESTIONS

Why do you do this (whatever the task is you are studying)?

How do you do this?

Gets at task-subtask structure

Then ask about each subtask

Why do you do it this way rather than some other way?

Attempts to get user to explain method and rationale so you can assess importance of the particular way of doing task (onion)

(98)

M ORE O PEN - ENDED Q UESTIONS

What has to be done before you can do this?

To get at sequencing issues

Please show me the results of doing this

Do errors ever occur when doing this?

How do you discover the errors, and how do you correct them? (Adapted from Nielsen et al., CHI ’86).

Encourage digressions; ask for elaborations

What else should I have asked you?

(99)

Q UESTIONNAIRES

General Criteria

Make questions clear & specific

Ask some closed questions with range of answers

Sometime also have a neutral or other option

Do test run with one or two people

(100)

L IKERT S CALE

Evaluation Questionnaire

Please complete the following questionnaire by indicating how strongly you agree or disagree with the following statements. Your responses will be kept confidential and will be used only for improving the interface that you worked with in this experiment.

1. I felt that the computer agent’s help was worthwhile. 1---2---3---4---5---6---7

Strongly Strongly Disagree Agree

2. I found the computer agent to be intrusive. 1---2---3---4---5---6---7

Strongly Strongly Disagree Agree

3. I found the computer agent's help to be distracting. 1---2---3---4---5---6---7

Strongly Strongly Disagree Agree

Seven-point Likert scale (use odd #)

Could also just use words (e.g., strongly agree, agree, neutral, disagree, strongly disagree)

(101)

O THER T YPICAL Q UESTIONS

Rank the importance of each of these tasks

List the four most important tasks that you perform (this is an open question)

List the pieces of information you need to have before making a decision about X, in order of importance

Are there any other points you would like to make? (open-ended opinion question; good way to end)

Same questions can be used in interview and in questionnaire; difference is in follow-up opportunity

(102)

F OCUS G ROUPS

Group of individuals — 3 to 10

Use several different groups with different roles or perspectives

And to separate the dominant personalities from the others

Want to avoid few people dominating discussion

Use structured set of questions

More specific at beginning, more open as progresses

Allow digressions before coming back on track

(103)

S TUDY DOCUMENTATION

Describes how things should be done rather than how they are done

Try to understand these discrepencies

(104)

C OMPETITIVE A NALYSIS

Look at competing products

Look for both good and bad ideas

Functionality

UI Style

Do user task performance metrics to establish bounds for your system

(105)

W HICH M ETHOD TO U SE ?

Depends on your own resources ...

Current knowledge of tasks & users

Context

E.g., can’t use think-aloud if tasks involve two people working together

(106)

O RGANIZING O BSERVATIONS

Organizing the observations serves two purposes

Understand the data

Helps present the data

(107)

T OOLS FOR S ENSEMAKING

Card sorting – to create Affinity Diagrams

Also useful for web site organization

Do it with multiple users

Flow charts

Task analysis diagrams

(108)

N OW W HAT ?

(109)

N OW W HAT ?

You have piles of notes, hours of video, surveys up to here…

How can you digest and represent the data, to turn it into information?

(110)

R EPRESENTING D ATA

Essential use cases

User characteristics + personae

Task outlines

Narratives

Hierarchies & Network Diagrams

Flow Charts

(111)

E SSENTIAL U SE C ASE (S CENARIO )

Description of important or frequent user interactions

Used to evaluate/walkthrough various design alternatives

Three elements

Name

User intention

System responsibility

Do not make assumptions about the UI design

(112)

E XAMPLE U SE C ASE

User Intention

Arrange a meeting

˙

Identify meeting attendees and constraints

Choose preferred date

System Responsibility

Request attendees &

constraints

Suggest potential dates

˙

Book meeting

Arrange-Meeting

(113)

[ From User Interface Design and Evaluation, The Open University ]

(114)

U SER C HARACTERISTICS &

P ERSONA

Description of user and what he or she wishes to do

Be specific/detailed, even give names and picture

Three persona for ATM usage follow

Adapted from User Interface Design & Evaluation, The Open University

Developed by Cooper (1999)

(115)
(116)

F ELIX (T EENAGE ATM U SER )

Felix is 13 and gets pocket money each week. He spends it with his friends, so doesn’t make regular deposits. He does receive gifts for his birthday, Christmas, etc. and saves that money for special purchases, such as a computer games

console or trendy clothes. He has an ATM card allowing him to make withdrawals when needed for his purchases.

(117)

S ANDRA (Y OUNG A DULT )

Sandra is 30, is married to Jason, has two children Todd(6) and Carly (18 months). They live in a subdivision that is about three miles from the town center, where the bank and stores are located. Jason uses the car for work, and works long hours, leaving at 6:45 am and returning at 8:00 pm. Sandra does not drive, so has to use public transportation.

She tries to run errands and shop while Todd is in school, so she does only has to take Carly to town with her. She typically needs to make two trips to town each week to get everything done. She uses a

stroller with Carly, and the bank is one flight up via escalator, so she

prefers to use the ATM outside the first floor, even though there is no canopy to protect customers from bad weather.

(118)

G RANDPA M ARVIN (O LDER A DULT )

Marvin is 68 years old, and his social security is deposited into his bank account at the start of each month. He goes to the bank every week, withdrawing enough cash for the week - for miscellaneous expenditure. Regular bills are paid by check.

He stands in line for a live teller, as he prefers the social

interaction to using an ATM, even though his new artificial hip makes standing in line uncomfortable. He does not have an ATM card.

(119)

T ASK O UTLINES

Lists, outlines, matrices

Use expanding/collapsing outline tool

Add detail progressively

Know in advance how much detail is enough

Can add linked outlines for specific subtasks

Good for sequential tasks, not so good for parallel

(120)

Using a lawnmower to cut grass

Step 1. Examine lawn

Make sure grass is dry

Look for objects laying in the grass

Step 2. Inspect lawnmower

Check components for tightness

Check that grass bag handle is securely fastened to the grass bag support

Make sure grass bag connector is securely fastened to bag adaptor

Make sure that deck cover is in place

Check for any loose parts (such as oil caps)

Check to make sure blade is attached securely

Check engine oil level

Remove oil fill cap and dipstick

Wipe dipstick

Replace dipstick completely in lawnmower

Remove dipstick

Check that oil is past the level line on dipstick

(121)

Describe tasks in sentences

Often expanded version of list or outline

More effective for communicating general idea of task

Not effective for

details

branching tasks

parallel tasks

Great as introduction to diagrams or outlines

N ARRATIVES

(122)

H IERARCHIES & N ETWORKS

Goals – what the user wants to achieve

Tasks – do these to achieve the goals

Sequential dependencies

Create new document before entering text

Multiple occurrences of tasks

Subtasks – lower-level tasks

The lowest-level subtasks get mapped onto one or several UI commands

i.e., move done by a copy followed by a paste

(123)
(124)

T ASK M ODEL — B ORROW A B OOK

Tasks to Goal complete goal

Subtasks to carry out one

task

(125)

C AN BE M ORE T HAN O NE

(126)

F LOWCHARTS

Start

Continue? Document

Input Display

Manual Operation

End Y

N

(127)

W ORKFLOWS

Documents going from one person/organization to another

Multiple participants in an activity

Web page sequencing

Browsing, purchasing, checkout

(128)

D OCUMENT F LOW E XAMPLE

Create Travel Request (Traveler)!

Approval (Dean)!

Notification of Approval

(Dean)!

Ensure Funds Available (Accounting)!

Notification of Approval

(Dean)!

No Funds

Make Trip (Traveler)!

Complete Expense Report

(Traveler)!

Approval

(Accounting)! Etc

(129)

M ULTIPLE P ARTICIPANTS

[ From Interaction Design, Preece Rogers and Sharp ]

(130)

S UMMARY OF T ASK A NALYSIS

Determine the data you need

Gather it using various appropriate methods and techniques

Represent the tasks and subtasks, plus other related information

Use this data to improve design

Note: be efficient!

(131)

U SING W HAT Y OUVE L EARNED

How do attributes of users & their tasks influence the design of user interfaces?

Are there some design guidelines we can derive from different attributes?

(132)

U SER P ROFILES

Attributes:

attitude, motivation, reading level, typing skill, education, system experience, task experience, computer literacy, frequency of use, training, color-blindness, handedness, gender,…

Novice, intermediate, expert

Manager, employee, contractor, …

(133)

M OTIVATION

User

Low motivation, discretionary use

Low motivation, mandatory use

High motivation, due to fear

High motivation, due to interest

Design goal

Ease of learning

˙

Control, power ˙

Ease of learning, robustness, control

Power, ease of use

(134)

K NOWLEDGE & E XPERIENCE

Experience

task system low high

low

low low high high high

Design goals:

– Many syntactic & semantic prompts – Efficient commands, concise syntax – Semantic help facilities

– Lots of syntactic prompting

(135)

J OB & T ASK I MPLICATIONS

Frequency of use

High — Ease of use

Low — Ease of learning & remembering

Task implications

High — Ease of use

Low — Ease of learning

System use

Mandatory — Ease of use

Discretionary — Ease of learning

(136)

D EFINE T ASKS

Consider the whole system

Determine who or what should perform each task and each step : e.g. the system remembers the login, but the user remembers the password

Determine criteria: efficiency, cognitive effort, time

Task x should take no more than y seconds

A new user should be able to create a new account in 5 minutes

(137)

D ESIGN & P ROTOTYPING

(138)

P ROTOTYPING THE I NTERFACE

Why prototype?

Creating the system is expensive

Start with low-fidelity mockups

Progress to prototypes

Storyboards, task diagrams, etc.

(139)

D ESIGN THE I NTERFACE

(140)

P APER & P HYSICAL P ROTOTYPING

(141)
(142)
(143)
(144)
(145)

W IREFRAME P ROTOTYPES

Paper or digital

Layout & functionality

Tools :

OmniGraffle

Browser plugins

e.g. Pencil project

(146)

6. Prototypage : mockup

CONCEPTION : UCD

plus fidèle

look & feel

pixel prêt

Outils :

Suite Adobe CS

OmniGraffle

(147)
(148)

W IZARD OF O Z

Simulate the system with a human wizard

(149)

P ROTOTYPING TOOLS

(150)
(151)

U SER T ESTING & E VALUATION

(152)

W HY T EST ?

Identify problems with software

You are not your user

The earlier you find your problems, the cheaper they are to fix

(153)

E VALUATION M ETHODS

Experimental, Observational

Typically with users

Controlled experiments based on usability requirements

Predictive

(without users)

(154)

P REDICTIVE E VALUATION

Idea:

Observational studies are expensive, time consuming

Let’s predict rather than observe usage

Save resources (quick, cheap)

(155)

A PPROACH

Expert review

HCI professional (not a real user) interacts with the system, tries to find usability problems

Ideally:

Has not used previous prototypes

Knows the problem domain

Understands the user’s perspective

(156)

P REDICTIVE E VALUATION M ETHODS

Heuristic Evaluation

“Discount” usability testing

Cognitive Walkthrough

(157)

H EURISTIC E VALUATION

Developed by Jakob Nielsen (www.useit.com)

Several experts evaluate the system according to simple and general heuristics

(158)

M ETHOD

Determine inputs

Evaluate the system

Collect observations

Rank by severity

(159)

I NPUTS

Who are the expers?

Learn domain, practices

What is the prototype to evaluate?

Mock-ups, storyboards, … or even a working system

(160)

E VALUATION M ETHOD

Use simple and natural dialog

Speak user’s language

Minimize memory load

Be consistent

Provide feedback

Provide clearly-marked exits

Provide shortcuts

Provide good error messages

Prevent errors

Reviewers evaluate system according to high-level usability principles :

(161)

P ROCESS

Perform at least two passes

Look at each screen

Flow from screen to screen

At each step, evaluate according to heuristics

Look for problems:

Subjective (if you think its a problem, it is)

(162)

D EBRIEFING

Gather all identified problems

Identify which ones aren’t really problems

Group, classify

Document and record the problems

(163)

O RDER BY S EVERITY

Scale from 0 to 4

Based on:

Frequency

Impact

Persistence

Market impact

(164)

A DVANTAGES

Cheap, good for small companies that can’t afford more

Can be performed on mockups

Experienced evaluators ideal

According to Nielson, 5 evaluators finds 75% of problems

(165)

L IMITATIONS

Evaluation is subjective, depends on reviewer expertise

Are these the right heuristics?

Are the identified problems really problems?

(166)

Références

Documents relatifs

CgA derived peptides, from MD simulations, and from globular proteins, we have strong evidence that the KE diad of amino acids interacts specifically with dopamine to control

The existence of comprehensive tables for solvation free energies in bulk solution(191) makes this parametrization rather unproblematic for solvated molecules and

The early infant vaccination strategy is estimated to prevent 2089 cases within the first 5 years of the vaccination programme, including a 55% reduction in VP cases in infants

The goal of the study is to analyze, from the perspective of researchers, the design of interfaces in order to: - evaluate the adherence of real-world interfaces to the

As such, this research lies at the intersection of the three fields of pedagogy, innovation and design thinking by asking how we can develop evaluation criteria to

This section presents the results of the two-way ANOVA, performed along with the one-way ANOVA presented in the main body of the paper, which examined the effect of gender and role

We build our proposal upon two main axes: (1) to provide more than one explanation, each targeted to a different user group, and (2) making explanations that follow

Here we report ob- servations that reveal a cold, clumpy accretion flow towards a supermassive black hole fuel reservoir in the nucleus of the Abell 2597 Brightest Cluster Galaxy