Usability Guidelines Principles Theories Lecture 4 De

Usability Guidelines, Principles & Theories Lecture 4 De. Sia. More www. desiamore. com/ifm 1

Overview of Lecture • Introduce “Usability” • Guidelines • Principles of Universal Design • Major design principles • Nielsen’s usability principles De. Sia. More www. desiamore. com/ifm 2

What is Usability ? • Usability is NOT Just common sense all art (and no science) stumbled onto by accident tacked on at the end free • Usability IS intuitive, safe, error-free, enjoyable best designed in from the beginning best achieved by knowing your users “The best predictor of customer satisfaction” “The next competitive frontier” De. Sia. More Usability Issues www. desiamore. com/ifm 3

What is Usability? • Usability can be defined as: “the capacity to be used by humans easily and effectively where, easily = to a specified level of subjective assessment effectively = to a specified level of human performance” (Shackel, 1990) • Usability affords the user easy access to the product’s functions De. Sia. More Usability Issues www. desiamore. com/ifm 4

What is Usability? The payoffs included: • Fewer last-minute design changes • Usable, appealing, and effective designs • Simple, less costly documentation • Credible marketing claims • Compelling product demonstrations • Increased sales • Reduced need for customer support • Longer market life De. Sia. More Usability Issues www. desiamore. com/ifm 5

Poor Usability Examples In a study of online merchandise purchases, “almost half of all attempts to make a purchase failed because the users could not work out how to complete the transaction. ” (1) • On behalf of the state of California, Lockheed Martin Information Management Systems built a computer system that would improve the state's child support collection rate. • new child-support collection cases dropped 40% in the first six months of use • 900 problems were documented, ranging from confusing software to vanishing parent records • $99 million system was scrapped in November 1997 -> most costly failed computer project in state government history (2). (1) The Economist (2001, April 14). Design Darwinism. (2) Katches, M. 1997. "State kills $99 million computer. " De. Sia. More Usability Issues www. desiamore. com/ifm 6

Usability Issues Other aspects of Usability: Ease-of-use Friendliness De. Sia. More Usability Issues www. desiamore. com/ifm 7

Ease-of-Use • Ease of use - a fundamental design criterion for a system • What constitutes a system that has a high ease of use characteristic? • One of the earliest attempts to define ease of use was by Miller who proposed the following criteria to measure it De. Sia. More Usability Issues www. desiamore. com/ifm 8

Ease-of-Use • Training time required to achieve satisfactory performance • Number of errors • Integration of automated and non-automated tasks • Habit formation rate • Number of users who want to use the system • Irrelevant supporting actions required to perform a task • Irrelevant display events • Time and frequency for user warm-up • Decision-making time • Failure recovery time De. Sia. More Usability Issues www. desiamore. com/ifm 9

Ease-of-Use • Is Rational Rose easy to use? ? De. Sia. More Usability Issues www. desiamore. com/ifm 10

Friendliness • Another commonly used term that is used to refer to computer systems is ‘friendly’ • What exactly is meant by a ‘friendly system’? • A system that scores high on the usability scale also scores highly on the friendliness scale • But does it mean something more? • Maybe the harmonious interaction of all the ease of use criteria? De. Sia. More Usability Issues www. desiamore. com/ifm 11

Friendliness De. Sia. More Usability Issues www. desiamore. com/ifm 12

Friendliness • A computer system should, like a friend, be pleasant to be with • Both friends and computer systems should possess desirable qualities • A number of researchers have tried to determine what these desirable qualities are • Some of their findings follow……. . . De. Sia. More Usability Issues www. desiamore. com/ifm 13

Friendliness Desirable qualities of a system • Adaptive • Transparent • Available • Comprehensible • Natural • Predictable • Self-explanatory • Forgiving • Efficient How does Rational Rose rate? De. Sia. More Usability Issues www. desiamore. com/ifm 14

Primary Goals of Usability • Effective to use • Efficient to use • Safe to use • Have good utility • Easy to learn • Easy to remember how to use De. Sia. More Usability Issues www. desiamore. com/ifm 15

Usability Guidelines are a basis for determining a course of action Principles are basic rules that guide or influence thoughts or actions Theories are general principles that explain or predict facts or events De. Sia. More www. desiamore. com/ifm 16

Usability Guidelines De. Sia. More Principles www. desiamore. com/ifm Theories 17

Usability Guidelines De. Sia. More Principles www. desiamore. com/ifm Theories 18

Guidelines • • Develop a shared language Promote consistency Record best practices 4 sample guidelines (Shneiderman & Plaisant, 2005): • • De. Sia. More Navigating the interface Organising the display Getting the user’s attention Facilitating data-entry Guidelines www. desiamore. com/ifm 19

Navigating the interface • Sample of the National Cancer Institutes guidelines: • • • De. Sia. More Standardise task sequences Ensure that embedded links are descriptive Use unique and descriptive headings Use check boxes for binary choices Develop pages that will print properly Use thumbnail images to preview larger images Guidelines www. desiamore. com/ifm 20

Organising the display • Smith and Mosier (1986) offer five high-level goals • Consistency of data display • Efficient information assimilation by the user • Minimal memory load on the user • Compatibility of data display with data entry • Flexibility for user control of data display De. Sia. More Guidelines www. desiamore. com/ifm 21

Getting the user’s attention • • De. Sia. More Intensity Marking Size Choice of fonts Inverse video Blinking Colour Audio Guidelines www. desiamore. com/ifm 22

Facilitating data entry • Smith and Mosier (1986) offer five high-level objectives as part of their guidelines for data entry • • • De. Sia. More Consistency of data-entry transactions Minimal input actions by user Minimal memory load on users Compatibility of data entry with data display Flexibility for user control of data entry Guidelines www. desiamore. com/ifm 23

Usability Guidelines De. Sia. More Principles www. desiamore. com/ifm Theories 24

Principles • More fundamental, widely applicable, and enduring than guidelines • Need more clarification De. Sia. More Principles www. desiamore. com/ifm 25

Principles • For any system or product: • Principles of Universal Design - for any system or product used by people • For computer systems: • Design principles - tend to be used mainly for informing a design • Nielsen’s usability principles - used mostly as the basis for evaluating prototypes and existing systems • Many principles of both are overlapping De. Sia. More Principles www. desiamore. com/ifm 26

Principles of Universal Design Ø Produced by a working group of architects, product designers, engineers and environmental design researchers Ø Defined a set of principles to guide a wide range of design disciplines included products and communications Ø These seven principles may be applied to evaluate existing designs, guide the design process and educate both designers and consumers about the characteristics of more usable products and environments De. Sia. More Principles www. desiamore. com/ifm 27

Principles of Universal Design Beneficiaries of universal design include: • People in a noisy shopping mall who cannot hear a kiosk • People who are driving their car who must operate their radio or phone without looking at it • People who left their glasses in their room • People who are getting older • People with disabilities • Almost anyone De. Sia. More Principles www. desiamore. com/ifm 28

Principles of Universal Design ü Equitable use ü Flexibility in use ü Simple and Intuitive ü Perceptible Information ü Tolerance for Error ü Low Physical Effort ü Size and Space for approach and use De. Sia. More Principles www. desiamore. com/ifm 29

Principles of Universal design üEquitable use De. Sia. More Principles www. desiamore. com/ifm 30

Principles of Universal Design 1. EQUITABLE USE The design is useful and marketable to people with diverse abilities. GUIDELINES • Provide the same means of use for all users: identical whenever possible; equivalent when not. • Avoid segregating or stigmatising any users. • Provisions for privacy, security, and safety should be equally available to all users. • Make the design appealing to all users. De. Sia. More Principles www. desiamore. com/ifm 31

Principles of Universal Design üFlexibility in Use De. Sia. More Principles www. desiamore. com/ifm 32

Principles of Universal Design 2. FLEXIBILITY IN USE The design accommodates a wide range of individual preferences and abilities. GUIDELINES • Provide choice in methods of use. • Accommodate right- or left-handed access and use. • Facilitate the user's accuracy and precision. • Provide adaptability to the user's pace. De. Sia. More Principles www. desiamore. com/ifm 33

Principles of Universal Design üSimple and Intuitive De. Sia. More Principles www. desiamore. com/ifm 34

Principles of Universal Design 3. SIMPLE AND INTUITIVE Use of the design is easy to understand, regardless of the user's experience, knowledge, language skills, or current concentration level. GUIDELINES • Eliminate unnecessary complexity. • Be consistent with user expectations and intuition. • Accommodate a wide range of literacy and language skills. • Arrange information consistent with its importance. • Provide effective prompting and feedback during and after task completion De. Sia. More Principles www. desiamore. com/ifm 35

Principles of Universal Design üPerceptible Information De. Sia. More Principles www. desiamore. com/ifm 36

Principles of universal design 4. PERCEPTIBLE INFORMATION The design communicates necessary information effectively to the user, regardless of ambient conditions or the user's sensory abilities. GUIDELINES • Use different modes (pictorial, verbal, tactile) for redundant presentation of essential information. • Provide adequate contrast between essential information and its surroundings. • Maximize "legibility" of essential information. • Differentiate elements in ways that can be described (i. e. , make it easy to give instructions or directions). • Provide compatibility with a variety of techniques or devices used by people with sensory limitations. De. Sia. More Principles www. desiamore. com/ifm 37

Principles of Universal Design üTolerance for error De. Sia. More Principles www. desiamore. com/ifm 38

Principles of Universal Design 5. TOLERANCE FOR ERROR The design minimises hazards and the adverse consequences of accidental or unintended actions. GUIDELINES • Arrange elements to minimise hazards and errors: most used elements, most accessible; hazardous elements eliminated, isolated, or shielded. • Provide warnings of hazards and errors. • Provide fail safe features. • Discourage unconscious action in tasks that require vigilance. De. Sia. More Principles www. desiamore. com/ifm 39

Principles of Universal Design üLow physical effort De. Sia. More Principles www. desiamore. com/ifm 40

Principles of Universal Design 6. LOW PHYSICAL EFFORT The design can be used efficiently and comfortably and with a minimum of fatigue. GUIDELINES • Allow user to maintain a neutral body position. • Use reasonable operating forces. • Minimise repetitive actions. • Minimise sustained physical effort De. Sia. More Principles www. desiamore. com/ifm 41

Principles of Universal Design üSize and space for approach and use De. Sia. More Principles www. desiamore. com/ifm 42

Principles of Universal Design 7. SIZE AND SPACE FOR APPOACH AND USE Appropriate size and space is provided for approach, reach, manipulation, and use regardless of user's body size, posture, or mobility. GUIDELINES • Provide a clear line of sight to important elements for any seated or standing user. • Make reach to all components comfortable for any seated or standing user. • Accommodate variations in hand grip size. • Provide adequate space for the use of assistive devices or personal assistance De. Sia. More Principles www. desiamore. com/ifm 43

Principles of Universal Design ØParticularly important for systems or products to be available to the public ØClosely linked with research on disabilities ØThese seven principles may be applied to evaluate existing designs, guide the design process and educate both designers and consumers about the characteristics of more usable products and environments De. Sia. More Principles www. desiamore. com/ifm 44

Summary of Lecture • Usability can be defined as the capacity to be used by humans easily and effectively • Ease-of-use • Friendliness • Guidelines- provided a number of sample guidelines • Principles - introduced major principles in HCI • Principles of Universal Design • Major design principles • Nielsen’s usability principles • Theories De. Sia. More Conclusion www. desiamore. com/ifm 45

Terms of Reference • Norman, D. (1990) The Design of Everyday Things • Preece, J. et al. (2002) Interaction Design • Shneiderman, B. & Plaisant, C. (2005) Designing the User Interface • Shackel, B. (1990) Human Factors and Usability • Smith, S. & Mosier, J. (2005) Guidelines for Designing User Interface Software • Foley, J. & Van Dam, A. (1995) Computer Graphics: Principles & Practices in C • Card, S. & Newell, A. (1983) The Psychology of Human. Computer Interaction • Karat, C. (1990) Cost-benefit analysis of usability engineering techniques • Miller, R. B. (1971) Human ease of use criteria and their tradeoffs De. Sia. More References www. desiamore. com/ifm 46