Chapter 9: Design Guidance and Design Rationale

Kevin JuangDavid BateWill Rodes

Topics

Sources of Design Guidance Standards Guidelines Style guides

Design Principles Simplicity Structure Consistency Tolerance

Accessibility Design Rationale

Design Guidance

User Interface Standard A set of internationally agreed design principles

or approaches Most common is ISO 9241

Ergonomic requirements for office work with visual display terminals (VDTs)

Situations to use Detailed starting point for development Publicize its use Client requires it

Design Guidance

Design Guideline Suggestion that is in between design principle

and design rule in terms of detail

Design Guidance

Style Guides Collection of design rules and guidelines Commercial or customized Situations to use

Applied starting point for development Target users already familiar Associate with certain products

Design Principles

Simplicity Keep the interface natural to the users Break down complex tasks into subtasks

Design Principles

Structure Group related features Use metaphors

Design Principles

Consistency Leverage user’s mental model to aid learning and

satisfaction Can enforce using style guides or GUI code reuse

Design Principles

Tolerance Use constraints Provide helpful error messages Emphasize recoverability

Forward error recovery Backward error recovery

Accessibility

The Principles of Universal Design W3C Web Content Accessibility Guidelines Section 508

Design Rationale

Record Design decisions Reasoning behind those decisions

Format Table sorted by date Brief text with illustrations when appropriate

Advantages Record design thoughts for future reference Communicate design decisions to others Aids technical support and marketing

Questions?