of ANALYZE
analysis stakeholders, field studies
Problem scenarios
claims about current practice
DESIGN
metaphors, information technology, HCI theory, guidelines
Activity scenarios Information scenarios Interaction scenarios
iterative analysis of usability claims and re-design
PROTOTYPE & EVALUATE
summative evaluation
Usability specifications
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formative evaluation
What is a prototype?
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Definition: A concrete but partial implementation of a design Can take many forms
- Sketches, set of screens, day-in-the-life video, virtual environment, limited-function system implementation, early-version of final implementation
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Is used for many purposes
- - - - - See if you ideas looks as good as they sound Show design concepts to users Convince management/sponsors to invest Contrast two (or more) technical alternatives Early and continuing evaluation
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Is a scenario a prototype?
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Approach Storyboard Mock-up (e.g., cardboard) Wizard of Oz Video prototype Computer animation Scenario machine Rapid prototype Working partial system
Description Sketches or screenshots illustrating key points in a usage narrative Fabricated devices with simulated controls or display elements Invisible human assistant simulates input, output, or processing functionality not yet available Video recording of persons enacting one or more envisioned tasks Screen transitions that illustrate a series of input and output events Interactive system implementing a specific scenario's event stream Interactive system created with specialpurpose prototyping tools Executable version of a system with a subset of intended functionality
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Why build a prototype?
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Make design concepts concrete so that they can be
- - - - - Experienced (more vividly) Discussed (more precisely) Critiqued (more technically) Evaluated (in the sense of "formative" evaluation} Engineered (systematically improved)
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Facilitate early and continuing participation by users and other non-developer stakeholders Specific technical issues (choose among risky or critical features, early and continuing evaluation) Enables evolutionary software development
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Prototyping Tradeoffs
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Glitzy vs premature commitment Expensive but realistic (wrt timing, content) vs early availability or throw-away efforts Constant "hill-climbing" iteration to local optima vs radical change and/or re-factoring of a design Dynamic (highly malleable) platforms vs organized, well-structured code base Low-fidelity vs high-fidelity
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Lo-Fi/Hi-Fi tradeoffs in Prototyping
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Low Fidelity Fast/easy to create/change Costs less "Roughness" helps to control premature commitment and invite participation investigate/guide Cannot detailed technical issues Less eyeball appeal
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High Fidelity Can slow things down, delay testing, distract effort Expensive Can test detailed performance issues Assess aesthetics in detail Impress clients/managers Provide guidance to technical writers May oversimplify complex implementation issues
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When would you prototype?
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Continually The specify-build-deploy waterfall is history All software development incorporates prototyping
- - - - Prototype to identify, analyze, validate requirements Prototype to develop and specify design Prototype to implement and integrate system Prototype to enable formative and summative testing
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Boehm's Spiral Model
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Examples of prototyping through (or instead of) the development process
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PICTIVE = Plastic Interface for Collaborative Technology Initiatives through Video Exploration Wizard of Oz
- SmartHelp
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Scenario Machines Off-the-shelf prototypes Evolutionary prototypes
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Low-Fidelity Participatory Design
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Wizard of Oz Prototyping
Experimenter monitors, responds as if system following detailed script
Test participant thinks he is working with actual system, pursuing prescribed tasks
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Animation, Scenario Machines 13
"Off-the-Shelf" Prototyping
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Jump-start the design and iteration process
- recruit existing tools and devices - integrate into approximation of a "system"
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Example as used in Virtual School project
- - - - telephone for audio conferencing Netmeeting for video conferencing, chat Web pages for project questions and answers email for interaction with ment...