What is an acceptable way to demonstrate the validity of test results under ISO 17025: 2017?

Demonstrating the validity of test results under ISO 17025:2017 is essential for ensuring the reliability and accuracy of testing procedures in laboratories. The correct approach, which involves the retesting of retained items, provides a concrete way to verify that the results obtained from earlier tests are still applicable and correct. Retesting ensures that any potential variations in the testing conditions, equipment calibration, or personnel technique are accounted for, leading to increased confidence in the results.

This method aligns with the principles of continuous improvement and quality assurance emphasized in ISO 17025, which necessitates that laboratories regularly reassess their methodologies and outcomes. By retesting retained items, laboratories can evaluate the consistency of their results over time, proving that their testing processes yield reliable data under controlled conditions.

Other approaches, such as relying solely on initial testing, testing with outdated methods, or disregarding previous results, do not meet the thoroughness required for validating results. Each of those methods could compromise the quality and trustworthiness of the test outcomes, failing to comply with the rigorous standards set forth by ISO 17025:2017.