Calibration Verification and Validation: Why These Terms Should Not Be Used Interchangeably

Calibration, verification, and validation are related activities, but they answer different questions. Calibration establishes a relationship between a reference and an instrument indication. Verification provides evidence that specified requirements have been met. Validation confirms that requirements are suitable for an intended use. Confusing these terms can lead to incorrect certificates, weak quality records, and unsafe decisions. This working paper explains the differences in plain language and shows how the activities can support one another. Practical examples from medical metrology demonstrate why a calibrated device is not automatically fit for every purpose and why a successful verification does not replace calibration. The main conclusion is that each activity must be selected according to the question that needs to be answered.