Design & Evaluation Chapter 3

1. Design & Evaluation Chapter 3 Rebecca W. Boren, Ph.D. Arizona State University IEE 437/547 September 13, 2010

2. The goals of enhancing performance, satisfaction, and safety are attained by several methods including • Conducting basic and applied research to broaden our understanding • Applying human factors principles, methods, and data to the design of new products or systems.

3. What is Human Factors Design?

4. New products or systems The Design of

5. The Design of • Modifications for existing products or systems RFID Stay fresh packaging for food,

6. Ergonomically sound environments The Design of

7. The Design of • Safety-related activities

8. Beware of ergonomic claims All claim to be modern and Ergonomic.

9. The Design of • Training programs & support material Driving safely as You get older. Driving simulator

10. How? • You will learn the tools of human factors design in later chapters of the textbook. • First, you must determine the users’ needs.

11. What is the First Law of Human Factors Design?

12. What is the First Law of Human Factors Design? “Know The User” for The User is Not You.

13. Methods to determine needs • Describe the population of users • Observation • Interviews • Questionnaires • Task analysis & flowcharts • Describe environmental conditions • Identify user preferences • Analyze data collected

14. Many products and systems are still designed and manufactured without adequate consideration of human factors.

15. Many products and systems are still designed and manufactured without adequate consideration of human factors. What is the problem?

16. As products become more technologically sophisticated they frequently become more difficult to use.

17. Product may be completed and then given to a human factors specialist to evaluate. Problems with that?

18. Human factors design can save companies time and money. To get the full benefit, human factors methods must be applied early in the design process.

19. The best way to demonstrate the value of human factors to management is to do a cost/benefits analysis. HF analysis is an extra cost. Must be justified.

20. What are the costs?

21. What are the costs? • Wages to human factors specialist • Materials used in questionnaires, computers, recording equipment. • Lost productivity for workers during study • These are only examples.

22. What are the benefits? • Benefits need to be quantifiable. Some examples: • Increased sales, • Decreased cost of providing training, • Decreased customer support costs, • Decreased development costs, • Decreased maintenance costs, • Increased user productivity, • Decreased user errors, • Improved quality of service,

23. What are the benefits? • Some more examples: • Decreased training time, • Decreased user turnover. • Increased employee satisfaction (lower turnover) • Decreases in sick leave • Decrease in number of accidents or acute injuries • Decrease in number of chronic injuries (e.g. cumulative trauma disorders) • Reduction in medical and rehabilitation expenses • Reduction in number of citations, fines, or lawsuits

24. Even small cost savings per task can add up in the course of a year. • Example: • Development of software used by 240,000 employees. • Human Factors design cost was $6,800 • Time-on-task monetary savings $6,800,000 for first year alone.

25. Must adequately determine user needs. • General approaches • Early focus on the user and tasks • Empirical measurement using questionnaires, usability studies, and usage studies focusing on quantitative performance data. • Iterative design using prototypes • Participatory design (where users are directly involved as part of the design team)

26. Human factors in the product design lifecycle • Front-end analysis • Iterative design and testing • System production • Implementation & evaluation • System operation & maintenance • System disposal

27. What is the most effective way to involve human factors in product design?

28. What is the most effective way to involve human factors in product design? All through the design process

29. Who might be included in a team? • Example: personnel from marketing • Who else?

30. What is user-centered design? • ‘Honor the user’ or ‘Know the user’ • Find a system design that supports the user’s needs rather than making a system to which users must adapt. • Must adequately determine user needs.

31. Front-end Analysis. Before the design solutions are generated, be able to answer the following questions • Who are the users? (also people who maintain, monitor, repair and dispose of the system) • What are the major functions to be performed by the system? What tasks must be performed? • What are the environmental conditions under which the system will be used? • What are the user’s preferences or requirements for the product? Example of laptop computer.

32. User Analysis • Create a complete description of the population of users (gender, age, educational level, physical size, any disabilities, familiarity with the type of product, and task-relevant skills) • Personas: a hypothetical person that represent key characteristics of the user population. (Personas exist to define the goals that the system must support and describe the capabilities and limits of users in concrete terms) • Remember: “The user is not you.”

33. Task analysis • Specifies the jobs, duties, task and actions that a person will be doing. Detailed and specific. • Tasks can be physical or cognitive How can we perform a task analysis?

34. How to perform a task analysis • Description of tasks • Hierarchical relationships • Information flow • Task sequence • Location and environmental conditions • Collect task data • Observation • Think-aloud verbal protocol • Interviews • Surveys and Questionnaires

35. Continued … • Analyze task data • Identify user preferences and requirements • Related to marketing • Users don’t always prefer what is best for them.

36. User Needs Design is an Iterative Process Refine Design Evaluation

37. Evaluation of design • Mock-up or prototype

38. Prototyping • Mock-ups are crude approximations • Prototypes have more of the look and feel and may have some functionality • Paper prototypes of software systems are screen designs sketched on paper.

39. Evaluation of design • Mock-up or prototype • Use data compendium or standards • Heuristic evaluation by an expert • Usability testing

40. Resources for Design Work • Data Compendiums • Human Factors Design Standards (military standards, ANSI/HFES-100 VDT) • Requirements and recommendations. • Human Factors Principles & Guidelines (presented in the textbook after chapter 3)

41. Heuristic design evaluation • Refers to a systematic evaluation of the product design to judge compliance with human factors guidelines or heuristics. • Usually performed by usability experts and does not include end-users.

42. Usability testing • Needed if the system involves controls and displays with which the user must interact • Usability is primarily the degree to which the system is easy to use or “user friendly.” • Who or what is being tested?

43. Usability testing • Example of testing an infant car seat.

44. Usability testing measures • Learnability (how easy the system is to learn)

45. Usability testing measures • Learnability • Efficiency (high level of productivity is possible)

46. Usability testing measures • Learnability • Efficiency • Memorability (casual user can return to the system after some period of not having used it, and without have to relearn the system)

47. Usability testing measures • Learnability • Efficiency • Memorability • Errors (few errors, easy recovery from errors, no catastrophic errors occur)

48. Usability testing measures • Learnability • Efficiency • Memorability • Errors • Satisfaction (users like the system)

49. Usability testing measures • How many subjects are enough for usability testing?

50. Usability testing measures • How many subjects are enough for usability testing? Ans: 4 to 5