1. Usability Engineering Lifecycles As Part of User-Centred Design

2. Notes (2 of 2) Usability Engineering Lifecycles

3. 3 What This Lecture Is About 1.The problem with software today 2.Usability engineering lifecyclesUsability engineering lifecycles  Next: early analysis activities

4. 4 Building a UI — What Do We Know? zPrinciples of UI development are neither obvious nor intuitive zPrinciples of UI development are not applied as often as they should be zDeveloping a UI is part of the larger problem of developing software zWhat are the big trends driving the field today? yThe software crisis ySoftware chronic problem

5. 5 Special Challenges to UI Development zThe communications explosion zThe media explosion zThe usability explosion

6. 6 The Communications Explosion zEssence of UI used to be one-user, standalone. Now moving more toward connectivity (e.g., WWW, CSCW, etc.) zSuperhighway; Communications services; Expanding user pops

7. 7 The Media Explosion zMice, pens, touch screens, video, speech, VR etc. zUI code is half the code zGets more complicated, the more the media (e.g., multimedia)

8. 8 The Usability Explosion zUsers want availability (open architecture) zIncreased awareness of costs of poor UIs

9. 9 The SE S/W Dev. Life Cycle Plus UE Waterfall model ySystematic, sequential approach to software development yBegins at system level and progresses through a series of phases

10. 10 Waterfall Model (picture) System Engineering Requirements Analysis Design Coding Testing Maintenance Classic Lifecycle Model

11. 11 Phases zSystems engineering and analysis zSoftware requirements analysis zSoftware design zCoding zTesting zMaintenance

12. 12 Notes Phases (Notes 2 of 2) zSystems engineering and analysis zSoftware requirements analysis zSoftware design zCoding zTesting zMaintenance

13. 13 Integrating UE Processes Curtis & Hefley Figure 5 (p. 31)

14. 14 Issues for Waterfall Model zThe waterfall model is the oldest and most widely-used paradigm for software engineering zFollowing any methodology imposes discipline on the software development process zIt appears to be easy to specify a timetable and costing for s/w developed with the waterfall model

15. 15 Some Problems (1) zReal problems rarely follow the sequential flow that model suggests: yIteration always occurs and yCreates problems in the application of the paradigm zDifficult for customer to state all requirements explicitly: yLife cycle has difficulty accommodating uncertainty that exist at beginning of many projects

16. 16 Some Problems (2) zCustomer must have patience zWorking version of the software will not be available until late in the time span

17. 17 Spiral Model zCommon model for risky development zIteration is built-in zIt is ‘rapid’ but still rigid

18. 18 Spiral Model

19. 19 The ‘Let's Get Real’ Model Hix & Hartson observed that UI developers worked in ‘alternating waves’ of top-down, bottom-up, inside-out, … *See Star Life Cycle figure +Fig. 4.2 in Hix & Hartson +Figs 6.13 in Preece et al. (2002) +Figs. 2.8, 18.5 in Preece et al. (1994)

20. 20 Star Life Cycle

21. 21 The Star Life Cycle Is… zNot sequential yActivities can proceed in any order zEvaluation-centred yEach activity is evaluated zInterconnected y Through the evaluation in the middle

22. 22 Getting Started—specifics SE/UI lifecycle divided into yDefinitional activities (Called ‘early system analysis activities’) yDevelopment/design activities

23. 23 Early System Analysis Activities zDocuments concerned with Detailing the UI from the user’s perspective zGoal Produce detailed documents that spell out as specifically as possible what the UI for the product will be like zDetails See the ‘early analysis activities’ slides

24. 24 Review Curtis & Hefley Figure 5 (p. 31)