Usability Engineering
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  • 1. Usability Engineering Manoj Chawla
  • 2. Agenda • What Is Usability? • Generations of User Interfaces • The Usability Engineering Lifecycle • Usability Heuristics • Usability Testing • Usability Assessment Methods beyond Testing • Interface Standards • International User Interfaces • Future Developments
  • 3. Definition • Learnability • Issues – Easy to learn – Users task • Efficiency of Use – Users individual – Expert users steady level of characteristics performance – User differences • Memorability • Age, gender, reasoning ability – Easy to remember – Experience with the system • Few and No catastrophic Errors – Experience with computers – Minimise frequency of errors in general • Subjective Satisfaction – Experience with the task – How pleasant it s to use the domain system
  • 4. Usability rules • Your best guess is not good enough • The user is always right • Users are not designers • Designers are not users • Vice presidents are not users • Less is more • Details matter • Help doesn’t always help • Usability engineering is a process
  • 5. Scenarios Source: Jakob Nielson
  • 6. Generations of user interfaces Generation Hardware Technology Users Advertising User interface Image paradigm -1945 Electro/Mechani Blinking lights & Inventors None None cal cards 1945-1955 Vacuum tubes Typewriter Experts/pioneers Calculator Programming batch 1955-1965 Transistors Line oriented Technocrats Information Command terminals processor languages 1965-1980 Integrated Full screen Specialised Mechanisation Hierarchical Circuits terminal groups w/o e.g. bank tellers menus and form knowledge fill-in 1980-1995 VLSI PC Professionals/Ho Personal WIMP bbyists productivity tool 1995-? Networked PC’s Easily portable Everybody Computer as Non command with cellular appliance based interfaces modem
  • 7. The lifecycle • Know the User • Guidelines and Heuristic • Individual User Characteristics Evaluation • Prototyping • Task Analysis • Scenarios • Functional Analysis • Interface Evaluation • The Evolution of the User – Severity Ratings • Competitive Analysis • Iterative Design • Goal Setting • Capture the Design Rationale • Financial Impact Analysis • Follow-Up Studies of Installed • Parallel Design Systems • Meta-Methods • Participatory Design • Prioritising Usability Activities • Coordinating the Total • Be Prepared Interface
  • 8. Heuristic evaluation • Graphic design and colour • Simple and natural dialogue • Speak the users language • Minimise the users memory load • Consistency • Feedback • Clearly market exits • Shortcuts • Good error messages • Prevent errors • Help and documentation
  • 9. Discount usability engineering • User and task observation – Simple visits to customer locations, observe and be quiet let the users work normally with out interference • Scenarios – Scenarios are prototypes with reduced functionality and features • Simplified thinking aloud – Test user allowed to use the system while being asked to think aloud. This allows the observer not just what but why
  • 10. Usability testing • Reliability • Stages of a Test • Validity – Preparation • Test Goals and Test Plans – Introduction • Test Plans – Running the Test – Debriefing • Test Budget • Performance Measurement • Pilot Tests • Thinking Aloud • Getting Test Users • Constructive Interaction • Novice versus Expert Users • Retrospective Testing • Between-Subjects versus Within-Subjects Testing • Coaching Method • Choosing Experimenters • Usability Laboratories • Ethical Aspects of Tests with • Cameraless Videotaping Human Subjects • Portable Usability Laboratories • Test Tasks • Usability Kiosks
  • 11. Measuring subjective satisfaction • Pleasing ________ Irritating • Complete ________ Incomplete • Cooperative ________ Uncooperative • Simple ________ Complicated • Fast to use ________ Slow to use • Safe ________ Unsafe
  • 12. Methods beyond testing • Observation • Questionnaires and Interviews • Focus Groups • Logging Actual Use • Combining Logging with Follow-Up Interviews • User Feedback • Choosing Usability Methods • Combining Usability Methods
  • 13. International user interface • May or may not involve translation • Icons – Resemblance icons e.g. envelope for mail – Reference icons e.g. depicts some object – Arbitrary icons – e.g. meaning by convention • Guidelines – Characters – more than ASCII character set – Numbers & currency – Time and measurement units • Resource separation – Separate the interface and the system functionality • Multi-local interfaces – Flexibility for different users to communicate
  • 14. The future • Speech input/output • Individualised interaction • Increased use of graphics • Dialogues designed by users • Increase computer knowledge • System adapts to user • Natural language • Self explanatory systems without manuals • Computer support for cooperative work
  • 15. Actions • Recognise the need for usability • Provide senior management support • Devote specific resources to usability engineering • Integrate UE activities into various stages of development • Make sure the user interfaces are subjected to user testing
  • 16. Usability trade-offs • Include accelerators for experts