Scenario-Based Usability Engineering

1. Scenario-Based Usability Engineering Chris North CS 3724: HCI

2. Outline • Scenario-based usability engineering: • Engineering • Usability • Metrics • Tradeoffs • Scenario-based • Scenarios • Claims analysis • HCI background: • History • @ VT • Class stuff: • HoF/S presentations • HW 1 • Project

3. Engineering • What is “engineering”? • What is “science”? • Myth: The user interface is tacked on at the end of the project • Why don’t Waterfall models work?

4. Palm vs. Newton

5. Usability • Usability = ??? • Metrics: What is measurable about usability? • How do we know if system A is ‘better than’ system B?

6. Usability Metrics • Ease of learning • learning time, retention time • Ease of use • user performance time, error rates • User satisfaction • surveys “user friendly”

7. Usability Tradeoffs • Can we simultaneously optimize all usability metrics? • What factors impact tradeoff decisions? • In usability engineering: • Identify tradeoffs • Choose based on design goals • Track tradeoffs for designrationale

8. + - + - Paper Pad vs. MS Word

9. Scenarios Stories about people and their needs and activities A problem scenario describes a current situation: Marissa was not satisfied with her class today on gravitation and planetary motion. She is not certain whether smaller planets always move faster or how a larger or denser sun would alter the possibilities for solar systems. She stays after class to speak with her teacher, Mr. Boring, but she isn’t able to pose these questions clearly yet, so Mr. Boring suggests that she re-read the text and promises more discussion tomorrow.

10. A design scenario describes an initial vision: Marissa, a 10th-grade physics student, is studying gravity and its role in planetary motion. She goes to the virtual science lab and navigates to the gravity room. In the gravity room, she discovers two other students, Randy and David, already working with the Alternate Reality Kit, which allows students to alter various physical parameters (such as the universal gravitational constant) and then observe effects in a simulation world. The three students, each of whom is from a different school in the county, discuss possible experiments by typing messages from their respective personal computers. Together they build and analyze several solar systems, eventually focusing on the question of how comets can disrupt otherwise stable systems. They capture data from their experiments and display it with several visualization tools, then write a brief report and send it for comments to her teacher Mr. Wright, who uses it for class discussion the next day. What makes a good scenario?

11. Scenario Elements • Setting • Actors (people, users) • Task goals (what I want to achieve) • Plans (how I will accomplish it) • Actions (do it) • Events (system response) • Evaluation (is that what I wanted?) What are the advantages of scenarios?

12. *Claims Analysis (see pgs 73-74) • Identify an important design feature (cause) • Identify the advantages and disadvantages of that feature (effects) How do you know?

13. Design • Maximize the +’s • Minimize the –’s

14. Iterative Design • Sometimes design is refinement

15. Iterative Design • Sometimes design is radically transformational

16. ANALYZE analysis of stakeholders, field studies claims about current practice Problem scenarios DESIGN Activity scenarios metaphors, information technology, HCI theory, guidelines iterative analysis of usability claims and re-design Information scenarios Interaction scenarios PROTOTYPE & EVALUATE summative evaluation formative evaluation Usability specifications

17. Some History of HCI

18. The Changing Face of Computer Use Professional programmers, “software psychology” 1960’s Business professionals, mainframes, command-line 1970’s Large, diverse user groups, “the computer for the rest of us” 1980’s World Wide Web and more, information access & overload 1990’s Ubiquitous computing, diversity in task, device, … 2000+

19. Some History of HCI • Vannevar Bush, 1945 “As We May Think” • Vision of post-war activities, Memex • “…when one of these items is in view, the other can be instantly recalled merely by tapping a button”

20. Some History of HCI • Douglas Engelbart, 1962 “Augmenting Human Intellect: A Conceptual Framework” • In 1968, workstation with a mouse, links across documents, chorded keyboard

21. XEROX (PARC) Alto and Star Windows Menus Scrollbars Pointing Consistency OOP Networked Apple LISA and Mac Inexpensive High-quality graphics 3rd party applications Some History of HCI

22. Large displays Small displays Peripheral displays Alternative I/O Ubiquitous computing Virtual environments Augmented Reality Speech recognition Multimedia Media space Artificial intelligence Software agents Games ... Future of HCI

23. Doug Bowman Dan Dunlap Roger Ehrich Steve Harrison Rex Hartson Deborah Hix Andrea Kavanaugh Brian Kleiner Scott McCrickard Chris North Manuel Perez Francis Quek Tonya Smith-Jackson Deborah Tatar Woodrow Winchester Center for HCI @ VT

24. VT GigaPixel Display

25. VTURCS • VT UGrad Research in CS • http://vturcs.cs.vt.edu • Andrew Sabri: • High-Res Gaming: WarCraft • Conference presentation, journal paper • Now at Electronic Arts

26. Assignment • Read: UE chapter 2 (Requirements Analysis) • HoF/S Presentations • Allan tran, josh wu • Homework #1 • Project Teams

27. Homework #1 • Qualitative discussion • Usability problems, errors, access, alternate tasks, … • Quantitative discussion • Data averages, min, max • Data visualization • Statistics, t-tests, …

28. Projects