Usability Test

Usability Testing is a type of software testing conducted to measure how real users interact with a software application, website, or mobile app. This test examines not functionality but how easily, quickly, and accurately users can complete specific tasks. Therefore, usability testing falls under the non-functional testing category within the software testing life cycle.

The primary goal of this test is to observe how users interact with the software in order to identify design flaws and usability barriers, then eliminate them. In other words, usability testing reveals whether the software meets the expectations and needs of its target audience.

Usability in the Context of Software Engineering

From a software engineering perspective, usability is a critical quality attribute that directly impacts the success of software products. Real-world projects are difficult to simulate in classrooms; therefore, usability testing is essential for teaching students a user-centered design approach in a real-world context. It has emphasized concepts such as validity, integrity, and reliability in usability evaluations and stressed that an effective usability test is only possible through accurate problem identification.

Integrating usability testing into all phases of the software development life cycle (SDLC) ensures that the product evolves in a user-focused manner from the design stage through to post-launch.

Key Features of Usability Testing

• Repeatability (Iterative Approach): Usability testing is not a one-time activity. It is repeated throughout the software development process to refine design decisions based on user feedback.
• User-Centered: Tests are conducted with real users of the software who reflect the target audience of the project.
• Manually Observed: Although some data can be collected automatically, real-time observation of user behavior is critical.
• Early Detection: Issues are identified in the early stages of development to prevent costly revisions.
• Broad Applicability: It is applicable to any domain involving user interaction, whether it is a website, mobile app, desktop software, or physical product.

Types of Usability Testing

By Method

• Moderated Testing: A facilitator guides users, observes their behavior, and collects feedback through open-ended questions.
• Unmoderated Testing: Users independently complete predefined scenarios. This method can be scaled to reach a broader user base.
• In-Person (Lab) Testing: Conducted in controlled environments where user behavior is directly observed.
• Remote Testing: Participants complete the test from their own environment. This approach effectively reflects real usage conditions.

By Objective

• Explorative Testing: User behavior and expectations are studied during early prototypes of the software.
• Comparative Testing: Different designs or software versions are compared.
• Assessment Testing: Task completion time, accuracy, and user satisfaction are measured.
• Validation Testing: Bottlenecks in the user experience are clearly identified.

Testing Process and Stages

The usability testing process is a multi-stage procedure requiring meticulous planning. The main objective is to understand how real users interact with the software through real tasks. According to sources, the process consists of the following steps:

Step 1 – Planning

• Define objectives: Determine which functions will be tested and which user scenarios are prioritized.
• Define target user profile: The characteristics of participants such as age, technical proficiency, and demographics must reflect the software’s actual users.
• Develop test scenarios: Create task definitions. For example, on an e-commerce site: “Add a product to the cart and proceed to checkout.”
• Select appropriate environment: Decide whether testing will be conducted remotely or in a lab.

Step 2 – Execution

• The moderator (if present) manages the process and guides participants.
• Observations, audio/video recordings, and screen captures are made while users perform assigned tasks.
• Participants may provide commentary using the “think-aloud” method when necessary.
• Technical issues are resolved during the test.

Step 3 – Analysis

• Quantitative data (completion time, number of errors) and qualitative data (user comments, behavioral observations) are collected.
• Recurring issues and patterns are identified.
• Problems are prioritized by severity (critical, medium, low).

Step 4 – Reporting and Improvement

• Findings are documented in detailed reports supported by graphs and tables.
• Recommendations for solutions are developed.
• Results are shared with developers and design teams.
• If needed, iterations are performed; the revised version is retested.

Measurement Criteria

The output of a usability test is not limited to observations alone. For effective measurement, three key parameters are used:

Effectiveness

• The rate at which tasks are successfully completed.
• The number of errors users make while completing tasks.
• For example, the percentage of users who can successfully initiate and complete a money transfer in a banking app.

Efficiency

• The time spent per task is measured.
• Additionally, the number of clicks or screen changes required to complete an action also indicates efficiency.
• Example: If User A completes a task in 2 minutes and User B takes 5 minutes, optimization is needed.

Satisfaction

• It expresses the user’s subjective opinion about the product.
• Surveys, interviews, or rating scales such as the Likert scale are used.
• According to ISO 9241-11, satisfaction is defined as the absence of discomfort and the presence of a positive attitude.

Tools and Techniques Used

Usability testing is supported by numerous tools and techniques:

• Eye Tracking: Identifies where users focus on the screen. For instance, if a critical button is not noticed, there is a design issue.
• Card Sorting: Users are asked to categorize the software’s menus or content structure themselves. This helps optimize information architecture.
• CREDO Matrix: Aligns data models with virtual window designs. It addresses capabilities for Create, Read, Edit, Delete, and Overview.
• Heuristic Evaluation: Experts evaluate the interface based on Nielsen’s ten usability principles, such as consistency, feedback, and error prevention.
• Session Recordings: User sessions are documented via screen and audio recordings for later behavioral analysis.
• First Click Testing: Measures where users click first to initiate a task. An incorrect first click indicates a confusing interface.
• Surveys and Feedback Forms: Collect quantitative feedback. However, these alone do not constitute usability testing—they serve as supporting elements.

Usability in Software Education

Usability is a modern component of software engineering education:

• Prototyping: Students develop prototypes during the design phase to test user interaction early.
• Problem-Based Learning (PBL): The concept of usability is learned practically while solving real-world problems.
• Task Modeling & Use Case: User-system interactions are modeled using UML diagrams.
• Formative Evaluation: Errors are identified before the final design is finalized.
• Effectiveness, Efficiency, and Problem Validity: Students measure these three parameters and prepare reports.
• Boehm’s 2025 Vision: A user-centered approach is one of the most important trends.

Advantages

• Customer Satisfaction: Users encounter intuitive interfaces instead of complex ones.
• Cost Advantage: Identifying issues during the prototyping stage is significantly cheaper than making changes after development.
• Competitive Advantage: An easy-to-use product quickly gains prominence in the market.
• Accessibility: A broader audience, including users with disabilities, can be reached.
• Brand Value: Positive user experiences create loyal customer bases.

Challenges

• Recruiting Participants: Finding users who represent the target audience is difficult and costly.
• Time and Cost: Especially lab-based tests require significant time and human resources.
• Subjective Feedback: Feedback varies because users have different levels of experience.
• Cross-Platform Complexity: Mobile, web, and desktop compatibility must be tested separately.
• Observer Bias Risk: Moderators or observers may unintentionally influence user behavior.
• Small Sample Size: Generalizing findings is difficult if the number of tests is limited.

Real-World Example

An e-commerce company conducted a usability test during the prototyping phase on the checkout process. Real users struggled to complete complex forms during payment. The company simplified the form design and removed unnecessary steps. As a result:

• The payment completion rate increased by 30 percent.
• Customer support requests decreased by 40 percent.
• The abandoned cart rate declined.

This example clearly demonstrates how usability testing directly impacts business outcomes.