DD ISO/TS 21748:2004

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
   7.3 Verification of repeatability
   7.4 Continued verification of performance
8 Establishing relevance to the test item
   8.1 General
   8.2 Sampling
   8.3 Sample preparation and pre-treatment
   8.4 Changes in test-item type
   8.5 Variation of uncertainty with level of response
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 express
   13.2 Choice of coverage factor
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 estimation
Annex B (informative) Experimental uncertainty evaluation
Annex C (informative) Examples of uncertainty calculations
Bibliography

Provides guidance for the evaluation of measurement uncertainties using data obtained from studies conducted in accordance with ISO 5725-2, and for the comparison of collaborative study results with measurement uncertainty obtained using formal principles of uncertainty propagation. Applicable in all measurement and test fields where an uncertainty associated with a result has to be determined.