CS3724 Human-computer Interactioncourses.cs.vt.edu/~cs3724/summer1-2005-pyla/notes-1/02-LC.pdf · 4 LC The Process of User Interaction Development zConnections of user interaction

CS3724 Human-computer Interaction

An Iterative, Evaluation-Centered Life Cycle For Interaction Development

Copyright © 2005 H. Rex Hartson and Deborah Hix.

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Topics

Connections of user interaction development to software engineeringDevelopment activities in the usability engineering life cycleUsability managementUser interface development team

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Typical Software Engineering LC

The Waterfall Model

System feasibility

Operations and maintenance

Implementation

Integration

Code

Detailed design

Product design

Software plans and requirements

System feasibility

Operations and maintenance

Implementation

Integration

Code

Detailed design

Product design

Software plans and requirements

System feasibilitySystem feasibility

Operations and maintenanceOperations and maintenance

ImplementationImplementation

IntegrationIntegration

CodeCode

Detailed designDetailed design

Product designProduct design

Software plans and requirementsSoftware plans and requirements

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The Process of User Interaction Development

Connections of user interaction development to software engineeringAll these figures depict communication paths, not temporal ordering of activitiesDistinction between design and implementationStart with basic software engineering concept:

Software design

Software implemen-

tation

Spec'ns

Con-straints and problems

Software design

Software implemen-

tation

Spec'ns


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Adding systems analysis, testing, and problem (application) domain

Req'ts

Software design

Spec'ns

Software implemen-

tation

Pgms

Main feedback: design flaws, errors, modifications

Test plan, criteria

Problem domain design

Req'ts

Errors, bugs

Major reconsiderations

Systems analysis

Software testing




Req'ts

Software design

Spec'ns

Software implemen-

tation

Pgms


Test plan, criteria


Req'ts

Errors, bugs


Systems analysis

Software testing




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Analogous activities for user interface development

Software design require-mentsUser

interface interaction

design

User interface software

design


implemen-tation

User-based

evalua-tion of

interface software

Interface design req'ts, usability spec'ns

Software imple-mentation spec'ns Pgms

Test plan, usability spec'ns

Main feedback is due to low usability: design flaws, errors, modifications

Errors, bugs


Systems analysis






design


design


implemen-tation

User-based

evalua-tion of

interface software





Errors, bugs


Systems analysis




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Connecting the processes together and adding rapid prototyping

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Systems analysis

Req'ts Spec'ns Pgms


Test plan, criteria


Req'ts

Errors, bugs




design


design


implemen-tation





User-based

testing and

evalua-tion of

interface and non-interface software

Rapid proto-typing

Formative user-based

evaluation

Usability spec'ns

Con-straints

and problems

Con-straints

and problems

Con-straints

and problems

Errors, bugs

Con-straints

and problems

Con-straints

and problems

Con-straints

and problems

Applica-tion

software design

Applica-tion

software implemen-

tation

Systems analysis

Req'ts Spec'ns Pgms


Test plan, criteria


Req'ts

Errors, bugs




design


design


implemen-tation





User-based

testing and

evalua-tion of


Rapid proto-typing


evaluation

Usability spec'ns

Con-straints

and problems

Con-straints

and problems

Con-straints

and problems

Errors, bugs

Con-straints

and problems

Con-straints

and problems

Con-straints

and problems

Applica-tion

software design

Applica-tion

software implemen-

tation

Systems analysis

Req'ts Spec'ns Pgms


Test plan, criteria


Req'ts

Errors, bugs




design


design


implemen-tation





User-based

testing and

evalua-tion of


Rapid proto-typing


evaluation

Usability spec'ns

Con-straints

and problems

Con-straints

and problems

Con-straints

and problems

Errors, bugs

Con-straints

and problems

Con-straints

and problems

Con-straints

and problems

Applica-tion

software design

Applica-tion

software implemen-

tation

Systems analysis

Req'ts Spec'ns Pgms


Test plan, criteria


Req'ts

Errors, bugs




design


design


implemen-tation





User-based

testing and

evalua-tion of


Rapid proto-typing


evaluation

Usability spec'ns

Con-straints

and problems

Con-straints

and problems

Con-straints

and problems

Errors, bugs

Con-straints

and problems

Con-straints

and problems

Con-straints

and problems

Applica-tion

software design

Applica-tion

software implemen-

tation

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The rest of this course is about just this part:

Systems analysis

User interface

interaction design


Rapid proto-typing


evaluation

Usability spec'ns

Con-straints

and problems

Systems analysis

User interface

interaction design


Rapid proto-typing


evaluation

Usability spec'ns

Con-straints

and problems

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The Wheel – Usability Engineering Life Cycle Process Model

Iterative, evaluation-centered process model for interaction developmentNew life cycle concept comes from:– The waterfall model – movement toward completion– Star (Hartson & Hix, 1989) – evaluation centered– LUCID (Cognetics, Inc.) – development activities– Boehm’s Spiral Model – iteration – New work by Helms & Hartson (2001) – put it

together

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– Star (Hartson & Hix, 1989)Evaluation centered

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– Boehm’s spiral model-evolution through iteration

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Determine objectives, alternatives, constraints

Evaluate alternatives, identify, resolve risks

Develop, verify next-level product

Plan next phases

Cumulative Cost

Commitment

Review

Determine objectives, alternatives, constraints

Evaluate alternatives, identify, resolve risks

Develop, verify next-level product

Plan next phases

Cumulative Cost

Commitment

Review

– Boehm’s spiral model abstracted

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– Spiral model adapted

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– Spiral unwound

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– Spiral unwound and stretched out

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– Waterfall with whirlpools

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Wheel

Connect-ing into Wheel, for inter-cycle iteration

Product concept

User/taskmodel

Usage scenarios

Screendesigns

Lo-fiprototype

Hi-fiprototype

Integration

Deployment

Operationalsystem

Close down

Global evaluation

hub

Direction of evolutionary advancement

Product concept

User/taskmodel

Usage scenarios

Screendesigns

Lo-fiprototype

Hi-fiprototype

Integration

Deployment

Operationalsystem

Close down

Global evaluation

hub


Product concept

User/taskmodel

Usage scenarios

Usage scenarios

Screendesigns

Lo-fiprototype

Hi-fiprototype

Integration

Deployment

Operationalsystem

Close down

Global evaluation

hub


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Life cycle=iterative configuration of cycles (each associated with a stage/form of the product)– Example: System analysis model, scenarios and

screen designs, lo-fi prototype, hi-fi prototype, software production & integration

Cycle is a sequence of four development activity types:

– Analyze– Design– Build– Evaluate

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Cycle as sequence of four types of development activities

Evaluate

Design

Analyze ImplementCycle ofactivities

Product

form in

Product form out

Evaluate

Design

Analyze ImplementCycle ofactivities

Product

form in

Product form out

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Zoom in on details of a generic cycle activity Activity type/

instance

Project role

Activity role

Tools/templates

Common databaseof documentation

TechniqueTechnique

Technique selection criteria

Product form in Product form

out

Relationships with other activities

Work products

Work products

Activity type/instance

Project role

Activity role

Tools/templates


TechniqueTechnique



out


Work products

Work products



Project roleProject role

Activity roleActivity role

Tools/templatesTools/templates


TechniqueTechniqueTechniqueTechnique




out


Work products

Work products

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Choose a technique for each activity type in each cycle

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– Shows how each activity type is assigned a technique, the role of the person doing the activity, support tools, and documentation

Example: In scenario and screen design cycles, design walk-through is used as evaluation technique

Basic Principles– Process is product oriented– Products evolve through cycles (cycles named for

product forms)

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– Each cycle is iterative– Each cycle contains same activity types– Each cycle is evaluation-centered– Work products (documentation) evolve over cycles– Process can be viewed at different levels

Process, cycle, activity, documentation

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Any part of the process is an instance of what is possible– Pick and choose cycles, activities, iterations to meet

schedule, budget, management styleIntegrate with software engineering development processValidated by Helms & Hartson (2001) in e-commerce start-up company

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Any part of process is instance of what is possible– Developers include their favorite UE methods and

techniques– Omit activities, cycles, iterations indicated by

management, budget, schedule, project scope, team composition

– Can be different every time

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Usability Management

The control mechanism for the iterationControl involves:– Establishing usability specifications– Evaluating against usability specifications– Performing impact and cost/benefit analyses

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Usability Management

– Deciding on changes to make to interaction design– Deciding when to stop iterating

Same process can be applied to develop user documentation or training course

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Roles on user interface development teamNote: Different roles, but not necessarily different people

– User interaction designer (or usability engineer or usability specialist)

– Evaluator (or facilitator)– User (and/or user representative)– Software engineer and/or programmer – Technical writer– Graphic designer– Application domain expert (also called subject

matter expert)

Meet the User Interface Development Team

Documents

CS3724 Human-computer Interactioncourses.cs.vt.edu/~cs3724/summer1-2005-pyla/notes-1/02-LC.pdf · 4 LC The Process of User Interaction Development zConnections of user interaction