1 Scope
This document provides
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a) a discussion of alternative experimental designs for the determination of trueness and precision measures including reproducibility, repeatability and selected measures of intermediate precision of a standard measurement method, including a review of the circumstances in which their use is necessary or beneficial, and guidance as to the interpretation and application of the resulting estimates, and
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b) worked examples including specific designs and computations.
Each of the alternative designs discussed in this document is intended to address
one (or several) of the following issues:
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a) a discussion of the implications of the definitions of intermediate precision measures;
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b) a guidance on the interpretation and application of the estimates of intermediate precision measures in practical situations;
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c) determining reproducibility, repeatability and selected measures of intermediate precision;
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d) improved1 determination of reproducibility and other measures of precision;
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e) improving the estimate of the sample mean;
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f) determining the range of in-house repeatability standard deviations;
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g) determining other precision components such as operator variability;
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h) determining the level of reliability of precision estimates;
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i) reducing the minimum number of participating laboratories by optimizing the reliability of precision estimates;
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j) avoiding distorted estimations of repeatability (split-level designs);
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k) avoiding distorted estimations of reproducibility (taking the heterogeneity of the material into consideration).
Often, the performance of the method whose precision is being evaluated in a collaborative
study will have previously been assessed in a single-laboratory validation study conducted
by the laboratory which developed it. Relevant factors for the determination of intermediary precision will have been identified in this
prior single-laboratory study.