Interactive System Design and Usability Engineering Notes

Core Concepts of Usability

  • Usability Definition: The ease with which users can effectively and efficiently complete tasks within a system.

  • Key Dimensions of Usability:

    • Effective: The ability of users to accomplish tasks using the system.

    • Efficiency: The speed and ease with which users can complete tasks once they are familiar with the system.

    • Learnability: The easiness for new users to learn how to use the system to achieve their goals.

    • Memorability: The capability of users to remember how to use the system after a period of time has elapsed.

    • Error Handling: The degree to which a system helps users prevent errors, recover from errors, and provides clear, meaningful error messages.

    • Satisfaction: The level of comfort and positive feelings experienced by users as a result of interacting with the system.

Usability Dimensions

Usability Engineering Life Cycle (UELC)

  • Definition: A structured methodology used for the development of software and systems to ensure they are efficient for end-users.

  • Core Approach:

    • Represents a step-by-step framework applied at each phase of the design process.

    • Initiates with understanding and identifying user needs.

    • Concludes with maintaining system functionality over time, fulfilling usability standards, and satisfying user requirements.

  • Detailed Life Cycle Workflow Elements:

    • Design Sprint:

    • User Research

    • Application of UX Principles

    • Finalization of User Flow

    • Information Architecture definition

    • Wireframing

    • Development:

    • Development Sprints

    • Sprint Retrospectives (Sprint Retro)

    • Agile Methodology implementation

    • Weekly status updates

    • Testing & QA:

    • Code Review (e.g., using tools like Codegrip)

    • Product Demos with Stakeholders

    • Sharing builds with clients for User Acceptance Testing (UAT)

    • Launch and Support:

    • Deployment to Beta live environment

    • Launch Optimization

    • Bug fixing

    • Infusion of user feedback

    • Final Launch

    • Incorporation of feedback and bug fixes into subsequent delivery plans

Usability Engineering Life Cycle Workflow

Sequential Phases of the Usability Engineering Life Cycle

  • Phase 1: User Research and Requirement Analysis:

    • Observation of users within their natural environment.

    • Execution of user interviews, surveys, and task analysis.

    • Creation of user personas and definition of explicit requirements.

  • Phase 2: Design and Prototyping:

    • Development of low-fidelity prototypes (wireframes) and high-fidelity prototypes.

    • Execution of usability testing to refine designs based on direct feedback.

  • Phase 3: Testing and Evaluation:

    • Utilization of evaluation methods, including:

    • Moderated testing

    • Unmoderated testing

    • A/B testing

    • Identification of critical usability issues and collection of user feedback.

  • Phase 4: Iterative Redesign:

    • Continuous refinement and enhancement of the system based on empirical testing results and user feedback.

  • Phase 5: Implementation and Deployment:

    • Delivery of the fully refined system for operational, real-world deployment.

  • Phase 6: Post-Release Monitoring and Maintenance:

    • Ongoing collection of user feedback via surveys and analytics platforms.

    • Monitoring of Key Performance Indicators (KPIs), such as system error rates and user behavioral metrics.

User-Centered Design (UCD)

  • Definition: A design approach that strictly prioritizes user needs, goals, and behaviors. The system must adapt to user preferences rather than forcing users to alter their behavior to adapt to the system.

  • The Five-Step Process of User-Centered Design:

    • Step 1: Understand the Context of Use:

    • Conduct user interviews, surveys, and contextual inquiries.

    • Identify distinct user groups and analyze their operational workflows.

    • Step 2: Specify User Requirements:

    • Gather comprehensive user needs through empirical research.

    • Create detailed personas and scenarios, and define quantifiable usability goals.

    • Step 3: Designing Solutions:

    • Develop structural low-fidelity prototypes (wireframes) through to interactive high-fidelity prototypes.

    • Apply foundational UI/UX design principles, such as consistency, visibility, and system feedback.

    • Step 4: Evaluating Designs:

    • Conduct direct usability tests with real target users.

    • Analyze test outcomes and refine design solutions based on user feedback.

    • Step 5: Iteration Process:

    • Ensure each evaluation phase leads directly into iterative design refinements.

    • Guarantee that the finalized product aligns with user requirements, expectations, and goals.

User-Centered Design Process Flow