ISO 英文 – INTERNATIONAL STANDARD IS0 TECHNICAL CORRIGENDUM 1 Published ISO Accuracy (Trueness and Precision) of Measurement Methods and Results – Part 5: Alternative Methods for the Determination of the Precision of a. Find the most up-to-date version of ISO at Engineering
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If a laboratory is not carrying out the tests within levels under repeatability conditions and allowing extraneous factors to increase the variation between the samples then unusually large k statistics will be seen in the graph that is derived from the between-sample ranges. If the participants in the experiment can be considered to be divided into two classes, those that produce good-quality data, and those that produce poor-quality data, then the robust methods should yield values for the repeatability and reproducibility standard deviations that are valid for the good-quality-data class, and not affected by the poor-quality data provided that the poor-quality-dataclass is not too large.
BS ISO 5725-5:1998
However, the h statistics for all the other laboratories for that level will be small, even if some of these other laboratories give outliers. Intermediate measures of the precision of a standard measurement method Part 4: In the absence of other information, the data responsible for these would be excluded, and the calculations repeated.
It is common to find this sort of pattern when plotting the data from a split-level design as in figure 1. Calculate the cell averages yii and enter them into a table as shown in table 3.
To analyse the data using the robust methods described here, ‘Algorithm A is applied to the cell averages, and ‘Algorithm S’ is applied to each series of kso in turn. International organisations, governmental and non-governmental, in liaison with ISO, also take pari in the work.
In the split-level design, each participating laboratory is provided laboratory standard deviation c with a sample of each of two similar materials, at each level of the experiment, and the operators are told that the samples are not identical, but they are not told by how much the materials differ.
An experiment on a heterogeneous material To test for stragglers and outliers in the between-test-resultranges, calculate Cochran’s statistic for each levelj as: Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Because of the natural variability of the material, there will always be some variability between bulk samples of the same product. The formulae presented in 5. In many chemical analysis methods, the matrix containing the constituent of interest can influence the precision, so for a split-level experiment two materials with similar 57255-5 are required at each level of the experiment.
The general average with summation over irand k: Izo the test portion is prepared so that it is all retained on a 10,Omm sieve. In practice, this procedure is often not easy to apply. Applying the method of 6. At the time of publication, the editions indicated were valid. Examine the data for consistency using the h and k statistics, described in subclause 7.
ISO Accuracy of Measurement Methods and Results Package
This is useful when it is possible to investigate the causes of the largest laboratory biases with the aim of taking corrective action. Alternative methods for the determination of the precision of a standard measurement method Status: Also, the figure 3 showed a consistent negative bias in the results from Laboratory 5.
Iand use this quantity as described in IS0 For test results, numbering in the order of increasing magnitude Additional symbols and abbreviations used in IS0 D Within-cell difference in a split-level experiment Number of samples laboratory at one level tested in a 0. The general case is considered in 5.
Hence, in IS0 However, the above equation may be derived by replacing p in equation 9 of IS0 Search all products by. Option a is to be preferred. 55725-5 method of analysis requires each difference to be calculated in the same sense a-b and the sign of the difference to be retained. Level 5 in that example is of particular interest because Laboratory 1 gave a cell average that was shown to be a near-straggler by Grubbs’ test, and Laboratory 6 gave a cell range that was shown to be a nearstraggler by Cochran’s test.
Alternative methods for the determination of the precision of a standard measurement method 1 Scope This part of I S 0 – provides detailed descriptions of alternatives to the basic method for determining the repeatability and reproducibility standard deviations of a standard measurement method, namely the split-level design and a design for heterogeneous materials; describes the use of robust methods for analysing the results of precision 5752-5 without using outlier tests to exclude data from the calculations, and in particular, the detailed use of one such method.
To derive equation 63 from equation 61note that the summation term in equation 61 may be expanded as follows: If this happens, the results of the precision experiment willwill be decreased and estimates of the betweenbe distorted: Precision refers to the closeness of agreement between test results. The basic method requires the preparation of a number of identical samples of the material for use in the experiment.
The data for Level 14 see table 4 are used here to illustrate the results that are obtained by robust analysis. Hence, as with leather, if a uniform level experiment is performed in which each ieo is sent one bulk sample at each level, the variability between the 5275-5 samples will increase the calculated reproducibility standard deviation of the test method, but if laboratories are sent two bulk samples at each level, then values for the reproducibility standard deviation can be calculated that exclude this variation.
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