Regulation on estimating measurement uncertainy for testing laboratories that using AOSC accreditation services

With reference to documents such as ILAC-P14:01/2013: ILAC Policy for Uncertainty in Calibration, ISO/IEC Guide 98-3:2008: Guide to the expression of uncertainty in measurement, and ISO/IEC 17025:2017 General requirements for the competence of testing and calibration laboratories, AOSC issued its Regulations on estimating measurement uncertainty for testing laboratories to ensure the consistency in reporting measurement uncertainty in testing report and the scope of accreditation for laboratories. “Laboratories” here means the testing laboratories that provide testing services in the field of chemistry, biology and other fields related to chemistry, biology.
Regulation on the evaluation of measurement uncertainty

AOSC categorizes the test methods based on measurement uncertainty as follows:
Group 1: Qualitative or semi-quantitative tests for which measurement uncertainty will not be required.
Group 2: Well-recognized test methods that specify limits to the values of the major sources of measurement uncertainty and specify the form for presentation of calculated results. In such cases, the laboratory is considered to have satisfied this clause by following the test method and reporting instructions.
Group 3: Chemical, environmental, or biological test methods based on published regulatory or consensus methods (for example: TCVN, FDA, EPA, AOAC, ASTM, APHA/AWWA, USDA/FSIS) for which the measurement uncertainty is not defined in the method. For these types of tests, estimation of measurement uncertainty is required.
Group 4: Non-standard methods, laboratory-designed/developed methods, standard methods used outside their intended scope and modified standard methods will require estimation of measurement uncertainty.
Statement of measurement uncertainty on test report
When testing laboratory presents measurement uncertainty in test report, the measurement uncertainty shall:
- Reported as expanded uncertainty;
- Presented in the same unit as that of the measurand or in a term relative to the measurement (e.g. percent);
- Coverage factor and the confidence interval shall be presented. (e.g. expressed at approximately the 95% confidence level using a coverage factor of k=2).
Please refer to GR-13 in VLAT Document on AOSC website for more information.

Source: AOSC

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