1 Usability Guidelines, Principles & Theories Lecture 4 DeSiaMorewww.desiamore.com/ifm

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

3 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” Usability Issues DeSiaMorewww.desiamore.com/ifm

4 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 Usability Issues DeSiaMorewww.desiamore.com/ifm

5 What is Usability? Usability Issues 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 DeSiaMorewww.desiamore.com/ifm

6 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). Usability Issues (1)The Economist (2001, April 14). Design Darwinism. (2)Katches, M "State kills $99 million computer." DeSiaMorewww.desiamore.com/ifm

7 Usability Issues Other aspects of Usability: Ease-of-use Friendliness Usability Issues DeSiaMorewww.desiamore.com/ifm

8 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 Usability Issues DeSiaMorewww.desiamore.com/ifm

9 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 Usability Issues DeSiaMorewww.desiamore.com/ifm

10 Ease-of-Use Is Rational Rose easy to use?? Usability Issues DeSiaMorewww.desiamore.com/ifm

11 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? Usability Issues DeSiaMorewww.desiamore.com/ifm

12 Friendliness Usability Issues DeSiaMorewww.desiamore.com/ifm

13 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……... Usability Issues DeSiaMorewww.desiamore.com/ifm

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

15 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 Usability Issues DeSiaMorewww.desiamore.com/ifm

16 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 DeSiaMorewww.desiamore.com/ifm

17 Usability Guidelines Principles Theories DeSiaMorewww.desiamore.com/ifm

18 Usability Guidelines Principles Theories DeSiaMorewww.desiamore.com/ifm

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

20 Navigating the interface Sample of the National Cancer Institutes guidelines: 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 DeSiaMorewww.desiamore.com/ifm

21 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 Guidelines DeSiaMorewww.desiamore.com/ifm

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

23 Facilitating data entry Smith and Mosier (1986) offer five high-level objectives as part of their guidelines for data entry 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 DeSiaMorewww.desiamore.com/ifm

24 Usability Guidelines Principles Theories DeSiaMorewww.desiamore.com/ifm

25 Principles More fundamental, widely applicable, and enduring than guidelines Need more clarification Principles DeSiaMorewww.desiamore.com/ifm

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

27 Principles of Universal Design  Produced by a working group of architects, product designers, engineers and environmental design researchers  Defined a set of principles to guide a wide range of design disciplines included products and communications  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 Principles DeSiaMorewww.desiamore.com/ifm

28 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 Principles of Universal Design Principles DeSiaMorewww.desiamore.com/ifm

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

30 Principles of Universal design Equitable use Principles DeSiaMorewww.desiamore.com/ifm

31 Principles of Universal Design 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. 1.EQUITABLE USE The design is useful and marketable to people with diverse abilities. Principles DeSiaMorewww.desiamore.com/ifm

32 Principles of Universal Design Flexibility in Use Principles DeSiaMorewww.desiamore.com/ifm

33 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. Principles DeSiaMorewww.desiamore.com/ifm

34 Principles of Universal Design Simple and Intuitive Principles DeSiaMorewww.desiamore.com/ifm

35 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 Principles DeSiaMorewww.desiamore.com/ifm

36 Principles of Universal Design Perceptible Information Principles DeSiaMorewww.desiamore.com/ifm

37 Principles of universal design 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. 4. PERCEPTIBLE INFORMATION Principles DeSiaMorewww.desiamore.com/ifm

38 Principles of Universal Design Tolerance for error Principles DeSiaMorewww.desiamore.com/ifm

39 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. Principles of Universal Design Principles DeSiaMorewww.desiamore.com/ifm

40 Principles of Universal Design Low physical effort Principles DeSiaMorewww.desiamore.com/ifm

41 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 Principles DeSiaMorewww.desiamore.com/ifm

42 Principles of Universal Design Size and space for approach and use Principles DeSiaMorewww.desiamore.com/ifm

43 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 and grip size. Provide adequate space for the use of assistive devices or personal assistance Principles DeSiaMorewww.desiamore.com/ifm

44  Particularly important for systems or products to be available to the public  Closely linked with research on disabilities  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 Principles of Universal Design Principles DeSiaMorewww.desiamore.com/ifm

45 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 Conclusion DeSiaMorewww.desiamore.com/ifm

46 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 References DeSiaMorewww.desiamore.com/ifm