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Usability and Accessibility Lecture 1 – 09/02/10. Dr. Simeon Keates. Course (provisional) overview. Note: subject to change!. Weeks 1 + 2: Project – done! Week 3: Intro to usability Week 4: Discount usability Week 5: Guest lectures Weeks 6-8: Universal access
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Usability and AccessibilityLecture 1 – 09/02/10 Dr. Simeon Keates
Course (provisional) overview Note: subject to change! • 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
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 correlated • Eating 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…
The Personal Information Point More on this later today…
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, efficiencyand satisfactionwith 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?
Measuring usability (source: Patrick Jordan “An introduction to usability) 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?
Measuring usability (source: Patrick Jordan “An introduction to usability) 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)
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 itto 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 are we aiming for? (Source: Jakob Nielsen “Usability Engineering”) Acceptability Practical acceptabilitySocial 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
What is a good interface? • Acceptable by the intended user group • (Jakob Nielsen “Usability Engineering”) Need to define: • What is the intendedusergroup? • 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 intendedusergroup? • 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.”
The fundamental stages of design • STAGE 1 - define the problem • STAGE 2 - develop a solution • STAGE 3 - evaluate the solution user wants/needs system requirements develop a usable system for “all” users verify/validate for all users
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 – Reactivity or proactivity? Reactivity - retrospective design consideration Proactivity - designed for usability
