usability and accessibility lecture 1 – 09/02/10

© Simeon Keates 2010

Usability and AccessibilityLecture 1 – 09/02/10Dr. Simeon Keates


Course (provisional) overview

Weeks 1 + 2: Project – done! Week 3: Intro to usability Week 4: Discount usability Week 5: Guest lectures Weeks 6-8: Universal access Weeks 9-10: User studies Week 11: Case studies / guest lecture Week 12: Usability and businesses Weeks 13-14: Complete project Week 15: Hand in reports

Note: subject to change!


Initial design feedback

All groups completed the task

Reports had very different styles• What each group thinks is important

Interesting variety of design rationales• What matters to different groups

Product classifications vs. list• More on this in Friday’s exercise

Sorting options…


Course aim

Usual answer:

To introduce and explore a toolkit of usability methods and techniques• We will be doing this

Additional (better?) answers:

To teach you to think for yourselves

To teach critical thinking• Classic ice cream/drowning example


Ice cream causes drowning!

The number of deaths due to drowning is higher on days when ice cream sales are high

The number of deaths due to drowning is lower on days when ice cream sales are low

Deaths by drowning and ice cream sales are strongly correlatedEating ice cream increases your chances of drowning!

Is this conclusion correct???


A quick definition…

“Product”• Product• System• Service• Web-site


What will we be looking at…

Project is web-based• For ease of coding…

Most examples will be software-based or web-based• Easier for experimentation…

Methods are extendable to hardware products• Some examples…


EPIRAID office workstation


The IRVIS prototype


The Personal Information Point

More on this later today…


The “Your Guide” kiosk and surround


Analogue teletext / television


Digital teletext / television


Getting started…What is “usability”?


Usability…

Q – What makes a “good” product?

Q – What makes a “better” product?

Q – How do you define “usability” and “accessibility”?

Q – When should usability be considered in the design process?

Q – When is a product OK to release to customers?

Q – How do you define “sufficiently” usable?


Why is usability important? (source: Patrick Jordan “An introduction to usability)

Annoyance• Products that are difficult to use cause annoyance and frustration and can

defeat their original purpose

Financial implications (product sales)• People do not want to buy those products

Financial implications (productivity)• People who have to use those products do not work as effectively and efficiently

as they should

Safety• Three Mile Island – officially “human error” but Norman claims bad design led to

misdiagnosis of what was happening in the reactor


How do you define “usability”?

Suggestions?

Typical answers: “The ability to get to a product’s functionality” “The ability to use a product successfully” “Intuitiveness / ease of learning” “Ease of use” “User friendliness”

We need something more concrete…

… and usable …


How do you define “usability”? (source: Wikipedia “Usability” entry) Ben Shneiderman and Jakob Nielsen (writing separately) claimed:

Usability is a part of “usefulness” and is composed of: Learnability: • How easy is it for users to accomplish basic tasks the first time they encounter

the design?

Efficiency: • Once users have learned the design, how quickly can they perform tasks?

Memorability: • When users return to the design after a period of not using it, how easily can

they re-establish proficiency?

Errors: • How many errors do users make, how severe are these errors, and how easily

can they recover from the errors?

Satisfaction: • How pleasant is it to use the design?


How do you define “usability”? (source: Patrick Jordan “An introduction to usability)

Guessability:• The effectiveness, efficiency and satisfaction with which specified users can

complete specified tasks with a specified product for the first time

Learnability:• The effectiveness, efficiency and satisfaction with which specified users can

achieve a competent level of performance on specified tasks with a specified product, having completed those tasks once previously

Experienced user performance:• The effectiveness, efficiency and satisfaction with which specified

experienced users can achieve specified tasks with a specified product


How do you define “usability”? (source: Patrick Jordan “An introduction to usability)

System potential:• The optimum level of effectiveness, efficiency and satisfaction with which it

would be possible to complete specified tasks with a specified product

Re-usability:• The effectiveness, efficiency and satisfaction with which specified users can

achieve specified tasks with a specified product, after a comparatively long period away from those tasks


How do you define “usability”? (source: ISO 9241-11)

ISO 9241 definition: “The effectiveness, efficiency and satisfaction with which specified

users achieve specified goals in particular environments”

- effectiveness: the accuracy and completeness with which specified users can achieve specified goals in particular environments

- efficiency: the resources expended in relation to the accuracy and completeness of goals achieved

- satisfaction: the comfort and acceptability of the work system to its users and other people affected by its use


Measuring usability (source: Patrick Jordan “An introduction to usability)

Effectiveness: the extent to which a goal or task is achieved

Task completion: • How much got done?

Quality of output: • Was what got done any good?



Efficiency: the amount of effort to accomplish a goal

Deviations from the critical (i.e. shortest) path: • How much did the user wander?

Error rate: • How often did the user make a mistake? How “bad” were the mistakes?• [More on this on Friday]

Time on task:• How long did it take?

Mental workload:• How hard did the user have to think?



Satisfaction: the level of comfort that the user feels when using a product and how acceptable the product is to users as a vehicle for achieving their goals

Qualitative attitude analysis: • Did you like it?

Quantitative attitude analysis: • How much did you like it? (e.g. benchmarking)


IMPORTANT POINT #1

Most definitions involve:• Effectiveness• Efficiency• Satisfaction

Q – Are these definitions mutually exclusive???

To be useful, usability needs to be quantifiable

And thus measurable…


Typical usability considerations (source: Wikipedia “Usability” entry)

Usability includes considerations such as:

Who are the users, what do they know, and what can they learn? What do users want or need to do? What is the general background of the users? What is the context in which the user is working? What has to be left to the machine?

Answers to these can be obtained by conducting user and task analysis at the start of the project.


Typical usability considerations (source: Wikipedia “Usability” entry)

Can users “easily” accomplish their intended tasks? • For example, can users accomplish intended tasks at their intended speed?

How much training do users need? What documentation or other supporting materials are available to help

the user? • Can users find the solutions they seek in these materials?

What and how many errors do users make when interacting with the product?

Can the user recover from errors? What do users have to do to recover from errors? Does the product help users recover from errors? • For example, does software present comprehensible, informative, non-

threatening error messages?

Are there provisions for meeting the special needs of users with disabilities? (Accessibility)


Getting started…The purpose of “design”


What is the aim of design? – Some common answers

Cheaper Faster Cleaner Safer Lighter Smaller, etc.


What is the aim of design? – User perspectives

I want it to do more I want to be able to use it I want to be able to understand it I want to feel in control of it I want to be able to trust it


What are we aiming for? (Source: Jakob Nielsen “Usability Engineering”)

Acceptability

Practical acceptability

• Utility

• Usability


What is the aim of design? – An example

Car A Car B

Fuel consumption >50 mpg <15 mpg

No. of passengers 7 2(+2)

Reliability Very high Very low

Running costs Very low Very high


The functional choice…


The aspirational choice…


What are we aiming for? (Source: Jakob Nielsen “Usability Engineering”)

Acceptability

Practical acceptability Social acceptability

Utility Aesthetics

Usability Desirability

Branding


What is the aim of design? – Some common answers

Cheaper• Everyone wants a Bic biro… | Mont Blanc pens

Faster• Every aeroplane will be Concorde… | Orient Express

Cleaner• Everyone wants a Toyota Prius… | Aston Martin, Ferrari, etc.

Safer• Everyone wants to stay home all day… | Extreme sports

Lighter• Everyone wants to only take hand luggage on holiday… | Jewellery

Smaller• Everyone wants to only take hand luggage on holiday… | Double whopper …


IMPORTANT POINT #2

There is no single universal product for everyone

There is no single product that will meet everyone’s needs

There is no single product that everyone will want to own

You can often only aim to satisfice• http://en.wikipedia.org/wiki/Satisficing


Designing an acceptable interface


What is a good interface?

Acceptable by the intended user group• (Jakob Nielsen “Usability Engineering”)

Need to define: What is the intended user group? What is acceptable?


Who are the users?

Often defined by marketing• “Target” users…• Defined by socio-economic factors

For usability can (should) take a broader view• Defined by user needs and wants• i.e. users who should be able to use the product

Accessibility takes an even broader view• [More on that in a few weeks]


What is a good interface?

Acceptable by the intended user group• (Jakob Nielsen “Usability Engineering”)

Need to define: What is the intended user group? What is acceptable?


Designing an acceptable interface – Social acceptability

Desirability• Do I want this?

Aesthetics• Does it look nice? Does it please my senses?

Branding• Does this product have values that I identify with?

Style• Does this product match my personal sense of style?


Designing an acceptable interface - Practical acceptability

Utility (a.k.a functionality)• Does it do what it is supposed to?

Usability• Can the user get to the functionality?

Accessibility• Can all users get to the functionality?• We will come back to this later…


Where do problems arise?

Focusing on technical development issues Focusing on deadlines

Not understanding the users Not focusing on the users

Designers designing for themselves(Alan Cooper “The inmates are running the asylum”)


Designers designing for themselves

“I am a user. Why shouldn’t I design for myself?”

“I understand the users. I don’t need to make any special effort to consider them.”

“I don’t have the time/budget/management approval to work with real users.”

“We’ve got user testing scheduled for the final phase of this project.”


Acceptable interfaces? – I


Acceptable interfaces? – II


A better approach to designing for usability…


The fundamental stages of design

user wants/needs system requirements

STAGE 1 - define the problem

STAGE 2 - develop a solution

STAGE 3 - evaluate the solution

develop a usable system for “all” users

verify/validate for all users


Designing for usability – Reactivity or proactivity?

Reactivity - retrospective design consideration

Proactivity - designed for usability

• cheap

• perceived to be easiest

• not particularly effective

• accessible products

• perceived to be expensive/difficult

• can be very effective - if done correctly


Designing for usability – Reliability and validity

Reliability How repeatable is your data collection? Have you done the thing “right” ?

Validity Has your data collection answered your question? Have you done the “right” thing?


The inclusive design ‘knowledge loop’

Case studies

Datarepresentation

Products/services

End-users

How to assessproducts/service

acceptability

How to capture &represent end-user

information

How to use theinformation toprovide correctproducts/services

How to assess datarepresentationacceptability

Informationusers


Methods for assisting the design of usable interfaces

Virtually all user-centred (or user sensitive) design methods

ONLY IF the correct users are chosen


Knowing the users – I

Q – What affects how acceptable an interface is to person? A – How it corresponds to their:• Capabilities• Experiences• Education• Expectations• Attitudes


Knowing the users – II

Q – How do users differ from other users? A – By their:• Capabilities• Experiences• Education• Expectations• Attitudes


Users…

Who are they?• Varies by project

What capabilities/characteristics?• Varies by project

How many?• Varies by project

How to report the results?• Varies by project


What user capabilities?

Step through the interaction to identify which user capabilities/characteristics matter

For example, at an ATM:• User asked “Which account to withdraw cash from?”• User reads the prompt (vision, cognitive / learning)• Finds the available buttons to choose between (vision, maybe motor)• Identifies the buttons (vision, cognitive / learning / memory)• Decides which one to press (cognitive / learning)• Activates it (motor, maybe vision)


Task analysis

What are the steps in making a cup of tea?


IMPORTANT POINT #3

The most useful response for any usability professional:

“It depends…”


Basic usability concepts…


Principles of usable design

The next few slides introduce the principles of usable design

Can you think of instances when these principles can lead to a less usable design?


Principles of usable design (source: Jordan)

Consistency: Designing a product so that similar tasks are done in similar ways



Compatibility: Designing a product so that its method of operation is compatible with

users’ expectations based on their knowledge of other types of products and the “outside world”



Consideration of user resources: Designing a product so that its method

of operation takes into account the demands placed on the users’ resources during interaction



Feedback: Designing a product so that actions taken by the user are

acknowledged and a meaningful indication is given about the results of those actions



Error prevention and recovery: Designing a product so that the

likelihood of user error is minimised and so that if errors do occur they can be recovered from quickly and easily



User control: Designing a product so that the extent to which a user has control over

the actions taken by the product and the state that the product is in is maximised



Visual clarity: Designing a product so that

information displayed can be read quickly and easily without causing confusion



Prioritisation of functionality and information: Designing a product so that the most important functionality and

information is easily accessible to the user



Appropriate transfer of technology: Making appropriate use of technology developed in other contexts to

enhance the usability of a product



Explicitness: Designing a product so that cues are given as to its functionality and

method of operation


Exercise:Card-sorting for the PIP


The Personal Information Point

Output

Input


Exercise - Background

The PIP has 6 buttons for input Those buttons can be used for any purpose you choose The LCD screen will display the output only• i.e. no touch input


Exercise - Details

PIP was to be used to advertise National Savings products Go to: http://www.nsandi.com/products/index.jsp Review the products• NOTE: Including those no longer on sale!

Design a set of paper prototypes for how that information can be displayed on the PIP

Write a (very brief) summary report explaining your decisions

QUESTION – What do you think is the minimum number of button presses needed to help a novice user decide which product to invest in?

✗


Exercise – New details

Design the PIP to support the sale of computers You have been given a list of computer models in your handout Research the models• They are all on Amazon.co.uk

Design a set of paper prototypes for how that information can be displayed on the PIP

Write a (very brief) summary report explaining your decisions


Exercise – New details

QUESTION – What do you think is the minimum number of button presses needed to help a novice user decide which product to invest in?

QUESTION – Do you think that this is the “best” possible design?


Friday room change!!!

Every Friday now 3A18 • not 2A12

Exercise rooms remain the same…

usability and accessibility lecture 1 – 09/02/10

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