1 5 6 7 8 Analyze and Produce Evaluate design understand - PowerPoint PPT Presentation

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5 6 7 8 Analyze and Produce Evaluate design understand paper-based With end-users user activities design prototype Design Produce dynamic Evaluate design prototype Design prototype With end-users Executable Implement final prototype user interface 2

9 10 Principle Description User familiarity The interface should use terms and concepts which are drawn from the experience of the people who will make most use of the system. Consistency The interface should be consistent in that, wherever possible, comparable operations should be activated in the same way. Minimal surprise Users should never be surprised by the behaviour of a system. Recoverability The interface should include mechanisms to allow users to recover from errors. User guidance The interface should provide meaningful feedback when errors occur and provide context-sensitive user help facilities. User diversity The interface should provide appropriate interaction facilities for different types of system user. 11 12 3

13 Interaction Main Main Application style advantages disadvantages examples Direct • Fast and intuitive • May be hard to • Video games • CAD systems interaction implement manipulation • Easy to learn • Only suitable where there is a visual metaphor for tasks and objects • Avoids user error • Slow for experienced • Most general-purpose Menu • Little typing users systems selection required • Can become complex if many menu options • Simple data entry • Takes up a lot of screen • Stock control, Form fill-in • Easy to learn space Personal loan processing Command • Powerful and • Hard to learn • Operating systems, flexible • Poor error management Library information language retrieval systems Natural • Accessible to casual • Requires more typing • Timetable systems users • Natural language • WWW information language • Easily extended understanding systems retrieval systems are unreliable 15 16 4

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21 22 23 24 Graphical user Command language interface interface GUI Command language manager interpreter Operating system 6

25 26 Information to Presentation be displayed software Display 27 28 View Controller State State View modification messages View Controller User Methods Methods Inputs Model queries Model & edits Model updates State Model Methods 7

29 30 Jan Feb Mar April May June 2842 2851 3164 2789 1273 2835 4000 3000 2000 1000 0 Jan Feb Mar April May June 31 32 1 0 10 20 4 2 3 Dial with needle Pie chart Thermometer Horizontal bar 8

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