1. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 1 User interface design

2. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 2 Topics covered l Design issues l The user interface design process l User analysis l User interface prototyping l Interface evaluation

3. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 3 The user interface l User interfaces should be designed to match the ____________________of its anticipated users. l System users often judge a system by its ________ rather than its _____________. l A poorly designed interface can cause a user to ______________________. l Poor user interface design results in ____________________________.

4. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 4 Human factors in interface design l Limited short-term memory People can instantaneously remember about ??? items of information. l People make mistakes Inappropriate alarms and messages can… l People are different How? l People have different interaction preferences

5. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 5 Design issues in UIs l Two problems must be addressed in interactive systems design ? l User interaction and information presentation may be integrated through a coherent framework such as ___________________.

6. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 6 Interaction styles

7. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 7 Multiple user interfaces

8. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 8 Web-based interfaces

9. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 9 LIBSYS search form

10. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 10 Information presentation l Information presentation is concerned with presenting system information to system users. l The information may be presented directly (e.g. text in a word processor) or may be transformed in some way for presentation (e.g. in some graphical form). l The Model-View-Controller approach is a way of supporting multiple presentations of data.

11. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 11 Information presentation

12. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 12 Information presentation l Static information. l Dynamic information

13. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 13 Information display factors l Is the user interested in precise information or data relationships? l How quickly do information values change? Must the change be indicated immediately? l Must the user take some action in response to a change? l Is there a direct manipulation interface? l Is the information textual or numeric? Are relative values important?

14. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 14 Alternative information presentations

15. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 15 Analog or digital presentation? l Digital presentation Advantages? l Analog presentation Advantages?

16. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 16 Presentation methods

17. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 17 Displaying relative values

18. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 18 Data visualisation l Concerned with techniques for displaying large amounts of information. l Visualisation can reveal relationships between entities and trends in the data. l Possible data visualisations are: Weather information collected from a number of sources; The state of a telephone network as a linked set of nodes; Chemical plant visualised by showing pressures and temperatures in a linked set of tanks and pipes; A model of a molecule displayed in 3 dimensions; Web pages displayed as a hyperbolic tree.

19. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 19 Colour displays l Colour adds an extra dimension to an interface and can help the user understand complex information structures. l Colour can be used to highlight exceptional events. l Common mistakes in the use of colour in interface design include: ???.

20. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 20 Color use guidelines

21. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 21 Error messages l Error message design is critically important. Poor error messages can mean that a user l. l Messages should be l. l The background and experience of users should be the determining factor in message design.

22. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 22 Design factors in message wording

23. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 23 Good and bad message design

24. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 24 The UI design process l UI design is an iterative process involving close liaisons between users and designers. l The 3 core activities in this process are: User analysis. …; System prototyping. … Interface evaluation. ….

25. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 25 The design process

26. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 26 User analysis l If you don’t understand what the users want to do with a system, … l User analyses have to be described in terms that …. l. l ____________ where you describe typical episodes of use, are one way of describing these analyses.

27. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 27 Analysis techniques l Task analysis Models the steps involved in completing a task. l Interviewing and questionnaires Asks the users about the work they do. l Ethnography Observes the user at work.

28. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 28 Hierarchical task analysis

29. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 29 Interviewing l Design semi-structured interviews based on open-ended questions. l Users can then provide information that they think is essential; not just information that you have thought of collecting. l Group interviews or focus groups allow users to discuss with each other what they do.

30. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 30 Ethnography l Involves l. l Valuable because l. l Also helps understand the role of social and organisational influences on work.

31. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 31 User interface prototyping l The aim of prototyping is to l Without such direct experience, it is impossible to judge the usability of an interface. l Prototyping may be a two-stage process:

32. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 32 Paper prototyping l Work through scenarios using sketches of the interface. l Use a storyboard to present a series of interactions with the system. l Paper prototyping is an effective way of getting user reactions to a design proposal.

33. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 33 Prototyping techniques l Script-driven prototyping l Visual programming l Internet-based prototyping

34. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 34 User interface evaluation l Some evaluation of a user interface design should be carried out to assess its suitability. l Full scale evaluation is very expensive and impractical for most systems. l Ideally, an interface should be evaluated against a usability specification. However, it is rare for such specifications to be produced.

35. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 35 Usability attributes

36. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 36 4 Simple evaluation techniques

37. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 37 HCI Guidelines (Golden rules) l General interaction Consistency Meaningful feedback Ask for verification Undo Reduce amount of info user memorizes Efficiency in dialogue, motion an thought System protection (forgive mistakes) Categorize function/organize screen geographically Context-sensitive help Simple short verb phrases

38. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 38 Cont. l Information display Only info needed displayed Use graph and charts Consistent labels and standard abbrev Maintain visual context Meaningful error messages CAPS, indent, etc. Windows to compartmentalize and geograpy “analog” displays l Data input Minimize # input actions (macros) Consistency between info display and data input Customize input allowed (dispense w/ sure?) Tune to user’s preferred mode of input (mouse/key) Assist all input actions Eliminate “micky mouse” inputs (defaults, no.00 on $)

39. ©Ian Sommerville 2006Software Engineering, 8th edition. Chapter 16 Slide 39 Standards l X-window system l PC windows l Microsoft