What is Design Rationale

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What is Design Rationale?

• Full documentation about soft/hardware
  development, especially the reasons certain
  design/programming decisions were made
• a representation for explicitly documenting the
  reasoning and argumentation that make sense of a
  specific artifact (MacLean et.al.)
• information that explains why an artifact is
  structured the way it is and has the behavior
  that it has (Conklin et.al.)

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Who benefits from thoughtful documentation?

• Software maintainers
• Trainers
• Marketing personnel
• New staff
• Original design team
• End users

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Main Features of Design Rationale

• A representation of the decision-making
  process, often graphical and/or hypermedia
• Developed during the design process
• Often considered part of the artifact

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Flavors of Design Rationale

• IBIS (Issue-Based Information Systems)
• Design Space Analysis
• Claims Analysis
• Scenario-based Analysis

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Issue-Based Information Systems

• Records questions about a design problem, called
  ISSUES
• Records POSITIONS on those issues
• Evaluates pros and cons on the positions, called
  ARGUMENTS

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A generic IBIS map
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gIBIS A Hypertext Version of IBIS

• Developed by Jeff Conklin and Michael Begeman in
  1989, originally for SUNs
• Reasons for developing gIBIS
• capture design history
• support CSCW and on-line design communication
• how to search large information areas

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gIBIS

• Browser-like environment
• Uses nodes to represent Issues, Positions, and
  Arguments.
• Maps relationships between nodes
• Another version WHAT (Writing with a
  Hypermedia-based Tool)
• Another version IWEB (Carnegie-Mellon)

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IWEB
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gIBIS generic map
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gIBIS sample nodes
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Criticisms of IBIS

• Conceptual difficulties not all participants
  agree on argumentation format
• Incorrect expectations users believe IBIS will
  make decisions for them
• Method-related difficulties classification of
  info awkward takes comments out of context hard
  to integrate new contributions

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Procedural Hierarchy of Issues (PHI)

• Attempts to address classification problems of
  IBIS
• Creates a hierarchy of arguments and issues
• Does away with pro/con classification

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Design Space Analysis (DSA)

• Developed by Allan MacLean et. al. In 1991
• Maps design options in hypermedia
• Applies QOC Questions, Options, Criteria
• Questions are design issues or decisions to be
  made
• Options are design alternatives
• Criteria are goals, supporting or negating Options

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Generic QOC map
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Example of DSA (1)
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Claims Analysis or Scenario-Based Design

• Main creator John Carroll, 1989
• Records the designers psychological claims for
  how his/her system will be used
• A scenario is created to replicate how a user
  might use the system, then the designers claims
  for that scenario are analyzed

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An example from Carroll

• A new programmer joins a team
• She accesses a video database
• She selects a user-scenario (e.g., how to save a
  document)
• The database displays video clips of system
  designers explaining their design choices

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Map of the Claims Analysis method
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Summary(1)

• Design Rationale (DR) is the history of why
  design decisions were made
• IBIS (Issue-Based Information Systems) isolates
  design questions (Issues), describes design
  alternatives (Positions), and lists pro and con
  Arguments.

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Summary(2)

• Design Space Analysis (DSA) breaks design process
  down into Questions (decisions to be made),
  Options (design alternatives), and Criteria
  (pro/con goals)
• Claims Analysis or Scenario-Based Design records
  designers claims about specific user scenarios
  is very user-centered.