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BS ISO 21748:2017 Guidance for the use of repeatability, reproducibility and trueness estimates in measurement uncertainty evaluation, 2017
- National foreword
- Foreword
- Introduction
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- 4 Symbols
- 5 Principles
- 5.1 Individual results and measurement process performance
- 5.2 Applicability of reproducibility data
- 5.3 Basic equations for the statistical model
- 5.4 Repeatability data
- 6 Evaluating uncertainty using repeatability, reproducibility and trueness estimates
- 6.1 Procedure for evaluating measurement uncertainty
- 6.2 Differences between expected and actual precision
- 7 Establishing the relevance of method performance data to measurement results from a particular measurement process
- 7.1 General
- 7.2 Demonstrating control of the laboratory component of bias
- 7.2.1 General requirements
- 7.2.2 Methods of demonstrating control of the laboratory component of bias
- 7.2.3 Detection of significant laboratory component of bias
- 7.3 Verification of repeatability
- 7.4 Continued verification of performance
- 8 Establishing relevance to the test item
- 8.1 General
- 8.2 Sampling
- 8.2.1 Inclusion of sampling process
- 8.2.2 Inhomogeneity
- 8.3 Sample preparation and pre-treatment
- 8.4 Changes in test-item type
- 8.5 Variation of uncertainty with level of response
- 8.5.1 Adjusting sR
- 8.5.2 Changes in other contributions to uncertainty
- 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
- 13.1 General expression
- 13.2 Choice of coverage factor
- 13.2.1 General
- 13.2.2 Level of confidence desired
- 13.2.3 Degrees of freedom associated with the estimate
- 14 Comparison of method performance figures and uncertainty data
- 14.1 Basic assumptions for comparison
- 14.2 Comparison procedure
- 14.3 Reasons for differences
- Annex A (informative) Approaches to uncertainty evaluation
- Annex B (informative) Experimental uncertainty evaluation
- Annex C (informative) Examples of uncertainty calculations
- Bibliography [Go to Page]