Lecture 8: Usability Testing
Overview
Usability testing focuses on understanding the ease of use and effectiveness of a system. This lecture covers essential evaluation methods including heuristic evaluation, cognitive walkthroughs, and think-aloud studies. You'll learn how to measure usability through objective metrics and gather meaningful user feedback to improve designs.
Lecture Material (PDF)
Evaluation Methods
Different evaluation methods help identify usability problems at various stages of development. Expert-based methods like heuristic evaluation are cost-effective, while user-based methods provide direct insights into real user behaviour.
Heuristic Evaluation
A method to identify usability problems using established usability principles (Nielsen, 1994). Experts review the interface against a set of heuristics like visibility, consistency, and error prevention.
Cognitive Walkthrough
Evaluating task flow based on user goals and system feedback (Wharton et al., 1994). Steps include defining tasks, identifying goals, and analysing whether users can determine correct actions.
Think-Aloud Protocol
Users verbalise their thoughts while interacting with a system. Provides insights into user decision-making processes and reveals confusion or frustration in real-time.
Contextual Inquiry
Observing users in their natural environment to gather insights. Combines observation with interview techniques to understand real-world usage patterns.
Usability Metrics
Objective measures help quantify usability and track improvements over time. These metrics provide concrete data to support design decisions and demonstrate the value of usability improvements.
Task Completion Rate
Percentage of users who successfully complete a task. Aim for >85% completion rate for critical tasks.
Error Rate
Tracks errors made during interaction. Lower is better - target around 5% or less for well-designed interfaces.
Time on Task
Measures efficiency by recording time needed to complete tasks. Compare against benchmarks to identify bottlenecks.
System Usability Scale (SUS)
A standardised 10-item survey to evaluate usability (Brooke, 1996). Scores above 68 indicate above-average usability.
Net Promoter Score (NPS)
Measures user loyalty based on likelihood to recommend. Users rate 0-10; scores are calculated as % promoters minus % detractors.
Testing Techniques
Various testing techniques provide different types of insights. Combining quantitative and qualitative methods creates a comprehensive understanding of usability issues.
A/B Testing
Comparing two versions of a system to determine which performs better. Provides quantitative data on user preferences and behaviour differences.
Eye-Tracking Studies
Analyse user focus and navigation patterns using specialised equipment. Produces heatmaps showing where users look and for how long.
Remote Usability Testing
Allows users to test systems from their own environment. Increases participant diversity and tests in realistic conditions.
Controlled Experiments
Studies that test usability changes under controlled conditions. Isolates variables to determine cause-and-effect relationships.
Design Principles for Usability
Good usability is built on solid design principles. These guidelines help create interfaces that are intuitive, efficient, and satisfying to use.
Consistency in Design
Ensures uniformity in navigation and interaction patterns. Users learn faster when similar actions produce similar results.
Minimizing Cognitive Load
Reduces mental effort needed to use a system. Present information progressively and avoid overwhelming users with choices.
Feedback Loops
Providing users with immediate and clear system feedback. Users should always know what the system is doing and whether their actions succeeded.
Error Recovery
Designing for smooth recovery from errors. Provide clear error messages and easy ways to undo or correct mistakes.
Progress Indicators
Show users their progress in multi-step tasks. Reduces uncertainty and helps users estimate time to completion.
Advanced Methods & Future Trends
Modern usability testing incorporates advanced techniques and emerging technologies to gather deeper insights and test with diverse user groups.
Persona Development
Creating user personas to guide design decisions. Personas represent key user groups and their goals, frustrations, and behaviours.
User Journey Mapping
Visual representation of user interactions over time. Maps the complete experience from initial contact through task completion.
Accessibility Testing
Ensures usability for users with disabilities. Follow WCAG standards to create inclusive designs.
Mobile & Responsive Design
Special considerations for usability on mobile devices. Adapts layout and functionality to different screen sizes and touch interactions.
Cross-Cultural Usability
Designing for a global and diverse audience. Consider language, cultural conventions, and regional preferences.
AI & VR in Testing
Exploring innovations like AI-powered analytics and VR environments for immersive usability testing.
Labs & Practical Exercises
Apply usability testing concepts through hands-on activities evaluating real forms and interfaces. Work through planning, conducting, and analysing usability tests.
Section 1: Introduction
Brainstorm usability factors, analyse well-designed vs poorly-designed forms, and review Nielsen's 10 Usability Heuristics.
Section 2: Planning
Define test objectives, recruit 3-5 participants, develop realistic tasks, and consider ethical requirements like informed consent.
Section 3: Conducting Tests
Practise think-aloud protocol facilitation, record observations, task completion times, and errors. Use NNGroup templates for data collection.
Section 4: Analysis
Synthesise observations, identify recurring issues, rate severity (low/medium/high), and generate concrete recommendations for redesign.
Tools & Further Reading
VLE Page
Course management and resources.