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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In the leather example discussed in 5.
It is incorrect to use such a test to decide if the variation between samples can be ignored in the analysis so that the test results in each cell are treated as if they are all obtained on the same sample. The values for all iiso are plotted in figures 2 and 3. Hence, in IS0 The decision as to whether to use robust methods or methods that require outliers to be discarded should be made by the statistical expert, and reported to the panel.
BS ISO 5725-5:1998
Hisher decision will have a substantial influence on the iiso values for the repeatability and reproducibility standard deviations. It yields a robust pooled value of the standard deviations or ranges to which it is applied. A method that is used to measure their ability to do this is the magnesium sulfate soundness test [21, in which a test portion of aggregate is subjected to a number of cycles of soaking in saturated magnesium sulfate solution, followed by drying.
The corresponding formulae for the split-level experiment are set out below. Option b wastes data, but allows the simple formulae to be used. Robust methods for data analysis Use in practice of accuracy values – – Parts 1 to 6 of IS0 together cancel and replace IS0which has been extended to cover trueness in addition to precision 575-5 intermediate precision conditions in addition to repeatability conditions and reproducibilityconditions.
Such graphs can help identify those laboratories that have the largest biases relative to the other laboratories.
Please first verify your email before subscribing to alerts. The derivation of the factors used in algorithm S is set out below. It gives a basic method for doing this using the uniform-level design. To derive equation 63 from equation 61note that the summation term in equation 61 may be expanded as follows: If there are empty cells in table 2, p is now the number of cells in column j of table 2 containing data and the summation is performed over non-empty isp.
It is also necessary to specify the number of determinations that are to isoo averaged to give a test result, because this affects the values of the repeatability and reproducibility standard deviations. Find Similar Items This product falls into the following categories. Hence, as with leather, if a uniform level experiment is performed in which each laboratory is io one bulk sample at each level, the variability between the bulk 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 5725-55 deviation can be calculated that exclude this variation.
A design for a heterogeneous material Note that q depends on the degrees of freedom of s. Calculation of the sum of squares for samples i 1 Sum of squares for Degrees of freedom for samples: The Analyst,pp. If it is necessary to reduce this uncertainty, the uniform-level design should be used instead.
It is a common experience when analysing data from precision experiments to find data that are on the borderline between stragglers and outliers, so that judgements may have to be made that affect the results of the 57255.
Methods for determination of soundness. The use of robust estimates of the standard deviations as the denominators in the h and k statistics, and of robust 57725-5 of the overall averages in the calculation of the h statistics, avoids this distortion.
Isp, because of considerations of cost, the answer will be two.
Also, the figure 3 showed a consistent negative bias in the results from Laboratory 5. The laboratory effects for each i with summation over r and k: This part of IS0 should be read in conjunction with IS0 because the underlying definitions and general principles are given there. The analysis of variance.
To show up inconsistent laboratories, plot both sets of these statistics in the order of the levels, but grouped by laboratory, as shown in figures 2 and 3. Thus each cell in the experiment contains four test results two test results for each of two samples.
If a laboratory is achieving generally worse repeatability than the others, then it will show up as having an unusually large number of large h statistics in the ixo derived from sio cell differences. Robust analysis for a particular level of an experiment on a heterogeneous material 6.
The between-sample ranges are smaller than the between-test-result ranges, suggesting that variation between samples is not important, at Level 6. Laboratory 5 gives only one cell average at Level 10 that is sufficiently extreme to be classed as an outlier by Grubbs’ test, but gives three other stragglers, and a strong indication in figure 3 that something is amiss in this laboratory.
Please download Chrome or Firefox or view our browser tips. There is, inevitably, a cost associated with obtaining extra information: An experiment on a heterogeneous material B informative Derivation of the factors used in algorithms A and S In an ido with a heterogeneous material, these requirements relate to the group of g x n tests in a cell,?.
ISO Accuracy of Measurement Methods and Results Package
Proceed to Checkout Continue Shopping. 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. Annexes B, C and D are for information only.
The method of analysis requires each difference to be calculated in the same sense a-b and the sign of the difference to be retained. The design for a heterogeneous material given in this part of IS0 yields information about the variability between samples which is not obtainable from the basic method; it may be used to calculate an estimate of reproducibilityfrom which the between-sample variation has jso removed.
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