Draft. Expected publication date is 09.2026
1.1 This document
— amplifies the general principles for designing experiments for the numerical estimation of the precision
of measurement methods by means of a collaborative interlaboratory experiment,
— provides a detailed practical description of the basic method for routine use in estimating the precision
of measurement methods, and
— provides guidance to all personnel concerned with designing, performing or analysing the results of the
tests for estimating precision.
NOTE
Modifications to this basic method for particular purposes are given in other parts of ISO 5725.
1.2 It is concerned exclusively with measurement methods which yield measurements on a continuous
scale and give a single value as the test result, although this single value can be the outcome of a calculation
from a set of observations.
1.3 It assumes that in the design and performance of the precision experiment, all the principles as laid
down in ISO 5725-1 are observed. The basic method uses the same number of test results in each laboratory,
with each laboratory analysing the same levels of test sample; i.e. a balanced uniform-level experiment.
The basic method applies to procedures that have been standardized and are in regular use in a number of
laboratories.
1.4 The statistical model of ISO 5725-1:2023, Clause 5, is accepted as a suitable basis for the interpretation
and analysis of the test results, the distribution of which is approximately normal.
1.5 The basic method, as described in this document, (usually) estimates the precision of a measurement
method:
a) when it is required to determine the repeatability and reproducibility standard deviations as defined in
ISO 5725-1;
b) when the materials to be used are homogeneous, or when the effects of heterogeneity can be included in
the precision values;
c) when the use of a balanced uniform-level layout is acceptable.
1.6 The same approach can be used to make a preliminary estimate of precision for measurement methods
which have not reached standardization or are not in routine use.
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