Lecture Notes for Human Factors
HCI Chapters 17-22

Copyright 1996 Richard Halstead-Nussloch, Ph.D.

Chapter 17 Principles of User-Centered Design

• What is design? (First creation in a two creation process)
• Fundamentals of design
  • Requirements
  • Representations (models)
• Designing software
  • Waterfall (pg 356)
  • Alternatives (Star, Spiral, W, etc.)

User-Centered Design

• Gould & Lewis (Olympic Message System)
  • Focus early on users and their tasks
  • Measure reactions using prototypes
  • Design iteratively
  • Usability factors evolve together - One control
• Methods (Chapter 18)
  • Soft Systems Methodology, Multiview Method
  • Cooperative design, Star adaptation

Requirements Gathering
Chapter 19

• Requirements gathering is understanding needs, leading to representations of
  • Problems with the current system
  • Requirements of the new system
• Types of requirements
  • Functional, e.g., Dataflow diagrams
  • Data, e.g., Entity Relationship diagrams
  • Usability, e.g., Usability metrics

Example Usability Metrics

• Time to learn
• Time on task
• Errors
• Percent correct
• Task completion
• Subjective ratings

Task Analysis - Chapter 20

• Task Analysis - A generic term for a bewildering range of techniques (pg. 410)
• Goal - A state of a system a user wants.
• Task - Activities required to achieve a goal.
• Action - A simple task, requiring no thought or problem solving to perform.
• Method - A linked sequence of tasks/actions

Types of Task Analysis
Modeling How-to & Knowledge

• Task Inventory (hand out) -- Describe goals
• Hierarchical Task Analysis (HTA-413+) -- Accurately describe steps
• Cognitive Task Analysis (417+) -- Represent & model knowledge required
• "How-to" models (step-wise procedures)
• Representing task knowledge (ER-like)

Structured HCI Design
Chapter 21

• Conceptual Design (Often in DFD)
  • Concepts
  • Semantics
• Physical Design - Visible System
• Task Allocation moves from Conceptual (Logical) to Physical Design
  • Allocate tasks to human, computer, HCI system
  • Various decision strategies

Envisioning Design
Chapter 22

• Dr. Rich's one word for this Chapter:

Prototype

• Use Scenarios, storyboards, snapshots, code, etc. to make visible your design