BS ISO 21748:2017

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols
5 Principles
6 Evaluating uncertainty using repeatability,
   reproducibility and trueness estimates
7 Establishing the relevance of method performance
   data to measurement results from a particular
   measurement process
8 Establishing relevance to the test item
9 Additional factors
10 General expression for combined standard
   uncertainty
11 Uncertainty budgets based on collaborative study
   data
12 Evaluation of uncertainty for a combined result
13 Expression of uncertainty information
14 Comparison of method performance figures and
   uncertainty data
Annex A (informative) - Approaches to uncertainty
        evaluation
Annex B (informative) - Experimental uncertainty
        evaluation
Annex C (informative) - Examples of uncertainty
        calculations
Bibliography

Provides guidance for: - evaluation of measurement uncertainties using data obtained from studies conducted in accordance with ISO 5725-2, and - comparison of collaborative study results with measurement uncertainty (MU) obtained using formal principles of uncertainty propagation.

This document gives guidance for

• evaluation of measurement uncertainties using data obtained from studies conducted in accordance with ISO5725‑2, and

• comparison of collaborative study results with measurement uncertainty(MU) obtained using formal principles of uncertainty propagation (see Clause14).

ISO5725‑3 provides additional models for studies of intermediate precision. However, while the same general approach may be applied to the use of such extended models, uncertainty evaluation using these models is not incorporated in this document.

This document is applicable to all measurement and test fields where an uncertainty associated with a result has to be determined.

This document does not describe the application of repeatability data in the absence of reproducibility data.

This document assumes that recognized, non-negligible systematic effects are corrected, either by applying a numerical correction as part of the method of measurement, or by investigation and removal of the cause of the effect.

The recommendations in this document are primarily for guidance. It is recognized that while the recommendations presented do form a valid approach to the evaluation of uncertainty for many purposes, it is also possible to adopt other suitable approaches.

In general, references to measurement results, methods and processes in this document are normally understood to apply also to testing results, methods and processes.