Prototyping

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Prototyping
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Definition - Prototype

• Artifacts that simulate or animate some but not
  all features of the intended system
• Iterative design

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How?

• Director
• Web Interface/Flash
• Java
• Denim http//guir.berkeley.edu/projects/denim/
• Powerpoint http//www.jansfreeware.com/articles/mi
  sc-prototyping.html

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Three main approaches

• Revolutionary
• Throw-away
• Actual prototype is discarded

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Three main approaches

• Incremental
• Product built one component at a time

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Three main approaches

• Evolutionary
• Basis for iterative design system evolves

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Rapid Prototyping

• Fast cycles, little or no code development
• Early visualization of product
• Crisp definition of requirements
• Early user testing
• Enhanced feedback to the user

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A technique not a tool

• Low-fidelity paper, scissors, pens or crayons,
  manual animation
• High-fidelity mimics the actual interface as
  closely as possible

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Content Sample Technique

• Select functionality
• Parts all users will use
• New features with high visibility
• Features with mission critical outcomes
• Parts of interface that might be problematic

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Content Approach - Scaling down

• Horizontal
• shallow and wide
• usability eval. less realistic, but covers
  functionality
• Vertical
• deep and narrow
• usability eval. realistic, but few functions
• details in functions included

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Content Approach

• Global
• wide and deep
• much of entire system
• get a feel for the final product
• Local
• narrow and shallow
• pick a single important detail
• stand-alone, not connected to rest of sys.

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Advantages

• easier to learn and use
• less affected by deadline pressures
• higher level of satisfaction
• common baseline or reference point
• users more enthusiastic
• enhanced communication of requirements
• effects the paradigm shift for users

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Pitfalls

• need buy in to be used in development
• difficulty in planning and scheduling
• reduction in programmer discipline
• view early prototype as final product
• limited accuracy in representing real system
• over-promising or misleading
• choice of tool and platform

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• trap of over-design
• if throw-away, revolutionary
• developers love their prototype
• make it good enough

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What to put into prototype

• Early
• needs to be testable
• test overall interaction metaphor
• some screens with format and content
• big picture
• Medium fidelity - fidelity to the final design
  may be low
• key details, critical features, metaphor
• guess at icon images, button and menu labels
• develop some functions user will perform
  frequently

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• Early, contd
• choose few important functions (I.e., critical
  task scenarios)
• prototype them fairly completely

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Conclusions

• Horizontal - best for early prototypes
• Vertical - best for later prototypes
• Global - useful throughout prototype cycle
• Local - limited time, for specific detail being
  worked out