usability and acceptability

S-72.124 Product Development in Telecommunications, 1999

Usability and acceptability

Design for successful telecommunications products


What is “a good product”

- for your company?- for the user of the

product?


Technical superiority is waste

if no-one can really use it for anything that is fun or

useful.


“There is a conflict of interest in the world of sofware development because the people who build it are also the people who design it. If carpenters designed houses, they would certainly be easier or more interesting to build but not necessarily better to live in. The architect is an advocate for the user. “

(Alan Cooper: About face)


A good telecom product?

• Supports the activities and communication of the user

• The whole system works, not only its parts

• Fits into the repertoire of communication systems of the user (compatibility - concergence!)

• The quality of the service is sufficient• The user can use it and likes to use it


Product maturity and usability

1) The Iron Age: Newly available functionality sells expensively, hard-to-use tolerated

2) The Functionality Competition: Feature lists

3) The Mature Product: Users want convenience and solutions

4) Transparency of product: Good usability makes product “disappear”


Acceptability Social acceptability

Practical acceptability

CostReliability

Compatibility

UtilityUsefulness

Usability

others

(Nielsen, 1993)

Acceptability and usability


Usability / ISO9241-11

goals

Effectiveness

Efficiency

Satisfaction

Intendedobjectives

Outcome ofinteraction

Usability

Users

Tasks

Equipmentand en-vironment


ISO 9241-11

Usability:The extent to which a product can be used by specific users to achieve specific goals with effectiveness, efficiency and satisfaction in a specific context of use.

effectiveness efficiency satisfaction


Nielsen’s Usability Attributes

• Learnability (opittavuus)• Efficiency (tehokkuus)• Memorability (muistettavuus)• Errors prevented (virheiden

tekeminen estetty)• Subjective satisfaction

(tyytyväisyys)


Inclusive design

the process of creating products which are usable by people

with the widest possible range of abilities,

operating within the widest possible range of

situations.


User-centered design

SYSTEM OPERATIONS

output001011001

001011001

001011001

User interface

Remote control

Mouse


Usability process

• Can be seen as a method for building as good as possible a system by removing things that cause problems using– user-centered approach– iterative developing & usability testing

& expert-reviews– cognitive science & experience– guidelines and principles


The Waterfall model of software design

Requirements specification

Architectural design

Detailed design

Coding and unit testing

Integration and testing

Operation and maintenance

(Dix et al. Human Computer Interaction, 1998)


The Waterfall model of software design with

feedback

Requirements specification

Architectural design

Detailed design

Coding and unit testing

Integration and testing

Operation and maintenance



Using design rules

• Standards: – ISO 9241 Ergonomic requirements for

office work with visual display terminals

• Guidelines– style guidelines for user interfaces of

various companies– various guideline collections published

by research projects and institutes– usability heuristics



Usability Engineering approach

• Including usability engineering goals into the design process

• Nielsen (Bellcore), Whiteside (IBM, Digital)

• Test of usability is based on measurements of user experience

• Addition of usability requirements to requirements specification



Sample usability specification

• Attribute: Backward recoverability• Measuring concept: Undo an erroneus

sequence• Measurement method: number of user

actions needed to undo error• Level now: No current product allows this• Worst case: as many steps as it takes to

do error• Planned level: Two actions• Best level: One undo action



• universal design• user-oriented design

– real value for end users– matched to user capabilities– fit for the purpose for which they were

designed

• systems oriented design– all technology operates within a context– provision process, training, support and

maintenance

(Trace center www pages)



• know the user, the task and the environment

• compare with existing systems• set goals• parallel design - competing

versions


• use heuristics and guidelines• test prototypes• assess usability• redesign… and redesign...• get feedback from usage of

completed system• participatory design


Involving the user into design

Product concept

Specifications

Prototyping

Final design

Follow-up

Focus groupsEthnographic methods

Benchmark testingTask analysis, Scenarios, user description, usability goals

Rapid prototypingExpert evaluationsPrototype testing

Final usability testing

User feedback


Product concept design

• Ideas for products and knowledge about user needs

• Ethnographic methods (origin anthropology): observing the user in real-life context

• Focus groups: discussing daily life• Participatory design methods• Day-in-the-life methods


From product idea to definition

Technical innovation

Market innovationUser study innovation

More user and marketing research

Product concept

Validation with more user research

Definition of product


Product concept

• The mission statement of the product– For whom, for what, why– on different stages of detail

• Is base of definitions• Iterative


Marketing vs. design

• Marketing: where are the customers, what would they pay

• Designer: How should this product work?

(Beyer ja Holtzblatt, 1998)


Product concept design

• Ideas for products and knowledge about user needs

• Ethnographic methods (origin anthropology): observing the user in real-life context

• Focus groups: discussing daily life• Participatory design methods• Day-in-the-life methods


Usability requirements specification

• User description: what kind of user groups is this designed for? User segments

• Task analysis: What are the user goals? How does the user work? Workflows, scenarios

• Environment analysis: external demands and requirements

• Usability goals


Iterative prototyping

• visualising early design ideas for user feedback

• competing prototypes for comparative design

• paper prototypes - interactive prototypes• horizontal: whole system at surface level• vertical: part of functionality in whole

depth• whole prorotypes: whole functionality• easy to produce - easy to discard!


Parallel and iterative design

(Nielsen, 1993)


User participation

• Involve actual users• users usually will not be able to come to

new design ideas, but they will react to existing design

• don’t ask what users want - let them try it out

• for long projects, refresh the user group - users start understanding the developers’ problems


Iterative prototypes

• Icons, terms, main view, horizontal/ vertical• scenarios as prototypes • rapid prototyping• early stages: paper mockups and

storyboards, navigation maps, verbal prototyping

• advanced stages: wizard-of-Oz-techniques, interactive prototypes

• interactive prototyping - modification on the fly


Prototype evaluation

• expert evaluations– cognitive walkthrough– heuristic analysis– visual walkthrough– guideline/ standard inspection

• usability testing– testing of the whole prototype– testing of icons, terminology, vertical

prototype


Usability testing

• Most new, surprising usability problems will not be found by expert evaluation methods

• Users representative of the intended user group perform typical tasks (scenarios from usability requirements) with the system; test leader observes and interviews the user

• Test design according to goals of the test - often the usability goals of the system


Follow-up usability evaluation

• user feedback• observing users in real work• log of usage - analysis for errors

and performance times• final data on achievement of

usability goals


“If achieving the users’ goals is the basis of our user interface design, then the user will be satisfied and happy. If the user is happy, he will gladly pay us money, and then we will be successful.”

(Alan Cooper: About Face)

usability and acceptability

Documents

good usability

digitaltest of usability

usability iso9241

good product

product disappearacceptability

mature product

sufficientthe user

human computer interaction