Usability Validation Planning: Select Participants and Scenarios From Use Risk

Focus on safe task performance

A participant saying that a demonstrated product is convenient does not establish safe use. Evaluate which errors could lead to harm and how the design reduces them. IEC 62366-1 addresses safety-related usability processes; establish applicability against the product and Korean requirements.

Development evaluations that identify problems differ from evaluation of the final design. This article focuses on planning the latter. See the usability requirements guide for the broader evidence framework.

Define user groups by use conditions, not job titles

A label such as “ten healthcare professionals” can conceal meaningful differences. Consider training, device experience, language, vision, hearing, dexterity, frequency of use and responsibilities. Patients, caregivers and professionals may perform different tasks requiring representation.

Do not copy a participant number from another device. Use applicable guidance, groups, tasks and evaluation objectives. Developers and specially trained employees may bring knowledge that changes outcomes. Record recruitment and exclusion criteria and actual participant characteristics.

Derive important tasks from risk analysis

Prioritize tasks linked to harm instead of having every button pressed once. Assess initial setup, dose/output selection, connection, alarm response, cleaning or disposal as relevant. Each task should connect to a risk, design control and observation criterion.

Do not embed the answer in a scenario. Give the reason and situation for performing a task instead of instructing the participant to press the red button. Align risks and controls with the risk-management file.

Represent marketed training and instructions

Screens, labels, packaging and instructions should represent the final design being evaluated. Define the content and delivery of actual training and the interval before use. Extra explanations immediately before evaluation can change results if customers would not receive them.

Represent lighting, noise, gloves, nearby equipment or time pressure where relevant. This is not a requirement to force every possible condition into every study. Explain what was and was not represented, its limitations and any further work needed.

Define intervention and investigation rules beforehand

Coaching a hesitant participant may complete a task without demonstrating independent performance. Define safety stops, distinctions between technical faults and use errors, and responses to requests for help. Record departures from the planned intervention rules and account for them in interpretation.

After observation, explore the participant’s reasoning without leading the answer. Explain how difficulties and close calls were reviewed, not merely whether errors were counted. Plan consent and data handling where recording is used, and preserve links between source observations and analysis.

Connect outcomes to design changes and residual risk

“User carelessness” alone can overlook design and environmental causes. Review task-level outcomes, causes, possible harm and the need for improvement. After a design change, assess both the problem addressed and possible new issues, then define further validation.

FDA materials address US review and do not automatically establish Korean submission scope. Bring user definitions, risk analysis, the final interface and the draft plan to a usability evidence review. Checking representation and scenarios before recruitment helps avoid results that are difficult to interpret.

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Sources checked: 2026-09-28. The tables and preparation steps are practical suggestions; confirm the legal submission scope and applicable standards for the particular product.

• IEC 62366-1:2015+AMD1:2020
• FDA Applying Human Factors and Usability Engineering to Medical Devices
• FDA Content of Human Factors Information in Medical Device Marketing Submissions