ISO 5725-2:1994 pdf download.Accuracy (trueness and precision) of measurement methods and results
1.1 This part of ISO 5725
- amplifies the general principles to be observed in designing experiments for the numerical esti-mation of the precision of measurement methods by means of a collaborative interlaboratory exper-iment;
- provides a detailed practical description of the basic method for routine use in estimating the precision of measurement methods;
- provides guidance to all personnel concerned with designing, performing or analysing the results of the tests for estimating precision.
NOTE 1 Modifications to this basic method for particular purposes are given in other parts of ISO 5725.
Annex B provides practical examples of estimating the precision of measurement methods by exper-iment.
1.3 It assumes that in the design and performance of the precision experiment, all the principles as laid down in ISO 5725-1 have been 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.
NOTE 2 Worked examples are given to demonstrate bal-anced uniform sets of test results, although in one example a variable number of replicates per cell were reported (un-balanced design) and in another some data were missing.
This is because an experiment designed to be balanced can turn out to be unbalanced. Stragglers and outlers are also considered.
1.4 The statistical model of clause 5 of ISO 5725-1:1994 is accepted as a suitable basis for the interpretation and analysis of the test results, the distribution of which is approximately normal.
2 Normative references
The following standards contain provisions which,through reference in this text, constitute provisions of this part of ISO 5725. At the time of publication, the editions indicated were valid. AII standards are subject to revision, and parties to agreements based on this part of ISO 5725 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
ISO 3534-1:1993, Statistics 一Vocabulary and sym-bols一Part 1: Probability and general statistical terms.
ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results 一Part 1:General principles and definitions.
4.2 Equations (2) to (6) of ISO 5725-1:1994,clause 5 are expressed in terms of the true standard deviations of the populations considered. In practice,the exact values of these standard deviations are not known, and estimates of precision values must be made from a relatively small sample of all the possible laboratories, and within those laboratories from a small sample of all the possible test results.ISO 5725-2 pdf download.