6 Human Factors: Design approach that increases product usability Usability Testing: Part of the human factors process: Evaluation of the product concept with interface experts and actual users Definitions of human factors and usability testing
7 Definitions of Usability Usability represents a balance between the TASK, the USER, and the SYSTEM to achieve a particular PURPOSE within an environment. Users can achieve their goals in an effective, efficient, and satisfactory way. Easy-to-use, early-to-learn, user friendly, easy-to- implement, and user accessible.
8 Why do we design unusable products? 1. Common-sense design is good enough. 2. The more functionality the better! 3. We can evaluate the interface later.... 4. Weve always done it this way. 5. My boss said I had to design it this way. 6. Users can customize their interfaces any way they want. 7. Im a user!
10 HFE Focus Design out the potential for human error Design in ease-of-learning and ease-of-use
11 Benefits of Human Factors Evidence shows that product usability is the market differentiator of the future. ( Harvard Business Review, July-August 1991, A Rappaport & S Halevi ) If you do not do usability testing on your product, then the customer will do it for you Reduced Development Cost Increased Sales Increased Product Quality Increased Customer Satisfaction Reduced Service and Maintenance Costs Reduced Documentation Reduced Liability
12 What HFE Brings to the Project: Knowledge of human perception, cognition, strength, size….
13 What HFE Brings to the Project: Knowledge of human perception, cognition, strength, size….
14 What HFE Brings to the Project: Tools for design and evaluation of systems for human use
15 What Does HFE Contribute? End user profiles, needs Use environment & workflow descriptions User interface features, design concepts System usability specifications Product Plan User interface design prototypes Design usability testing User interface design specifications Product Specifications Use error/hazard analysis User interface design requirements Training and documentation requirements Product Requirements Inputs to Clinical Study Plan Usability testing, field usability studies Regulatory Submittals Human Factors input to investigation of use error events Gathering and analysis of customer feedback Product Planning
16 Key Characteristics of the Human Factors Approach Incremental, iterative development User focused design Goal-directed, evaluation-centered design Multi-method, empirical evaluation Rapid prototyping and development
25 What Is a Usability Study What Is a Usability Study A subjective and objective evaluation of how well a system meets the needs of its users. System – a combination of the product, the environment, and the user Needs – expectations, knowledge, skills, abilities, performance, norms… Users – purchasers, managers, end users, maintainers… Usability is an iterative process
26 What Is a Usability Study What Is a Usability Study Types of usability studies Inquiry – used to obtain information about users likes/ dislikes, needs, system understanding via observation, interview, and survey Field observation, Focus groups, Interviews and Questionnaires Testing – used to identify where interface could better support user by having users work on typical tasks with the product Performance measurement, Thinking aloud, Teaching method Inspection – used to identify deviation from established guidelines or standards through expert review Heuristic evaluations, Cognitive and Pluralistic walk- throughs, Feature and label inspections
27 How Do You Prepare a Study How Do You Prepare a Study Map Usability Concerns to Participants Determine sample size Within-subjects requires fewer participants than between- subjects Usability focused on finding gross problems, statistical power less important, small frequent samples OK * Nielsen and Landauer, 1993. A mathematical model of the finding of usability problems. Proc. ACM INTERCHI 93 Conference, Amsterdam, the Netherlands, 24-29 April Usually 5-8 participants »4 participants will find 70% of major usability issues »8 participants will find 85%, diminishing returns above 8* Use a larger sample if investigating a specific interface issue
28 Recap: Typical HFE Deliverables HFE Plan HFE Analyses (e.g., user profiles, task analyses, use error analyses) User Interface (UI) Design concepts, mockups, prototypes UI Design Requirements UI Design Specifications Usability Testing Reports and Summaries
29 References References Books Bias and Mayhew (1994). Cost-Justifying Usability. Chestnut Hill, MA: Academic Press. Cooper (1999). The Inmates are Running the Asylum. Indianapolis, IN: SAMS Dumas and Redish (1993). A Practical Guide to Usability Testing. Norwood, NJ: Ablex Publishing. Mayhew (1999). The Usability Engineering Lifecycle. San Francisco, CA: Morgan Kaufmann Publishers. Nielsen (1993). Usability Engineering. Chestnut Hill, MA: Academic Press. Bogner (1994). Human Error In Medicine. Hillsdale, NJ: Lawrence Erlbaum Associates.
30 References References Websites Jakob Nielsens site: www.useit.comwww.useit.com Usability evaluation site: www.cs.umd.edu/~zzj/UsabilityHome.html www.cs.umd.edu/~zzj/UsabilityHome.html Examples of poor product designs: www.baddesigns.comwww.baddesigns.com Articles Get inside the lives of your customers, Patricia Seybold, HBR, May 2001
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