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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Y Ratio of the reproducibility standard deviation to the repeatability standard deviation Identifier for a particular test result in a laboratory i at levelj Between-laboratory interlaboratory Identifier for isi bias Between-test-sample Operator-different Probability Repeatability Reproducibility Time-different Within-laboratory intralaboratory For test results, numbering in the order of obtaining them odor L m s Bias of the measurement method Estimate of 6 A S M O Laboratory bias Estimate of A Detectable difference between two laboratory biases or the biases of two measurement methods True value or accepted reference value of a test property Number of degrees of freedom?
There were nine participating laboratories, and the experiment contained 14 levels. You may delete a document from your Alert Profile at any time.
However, when the aim of the precision experiment is to discover the variability that will be experienced in practice for example, when vendors and purchasers test samples of the same product then it is necessary for the variability arising as a consequence of the heterogeneity of the material to be included in the measures of the precision of the measurement method.
The symbols used in IS0 are given in annex A.
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.
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. In an experiment on a heterogeneous material, the results of applying these tests should be acted on in the following order. To check the consistency of the between-sample ranges, calculate the k statistics as: This extra information may be valuable.
Industrial Quality Control, 15,pp. Please download Chrome or Firefox or view our browser tips. The corresponding formulae for the split-level experiment are set out below. In the sand example discussed in 5.
For example, if, at one level of an experiment, one laboratory gives a cell average that is an outlier, and much more extreme than any other outlier at that level, then it will show up in a graph of h statistics as giving an exceptionally large h for that level.
Precision refers to the closeness of agreement between test results. Usually, because of considerations of cost, the answer will be two. Robust analysis for a particular level of a uniform-level 57225-5 If this lso, the results of the precision experiment willwill be decreased and estimates of the betweenbe distorted: The faster, easier way to work with standards. They do not combine individual test results in a robust manner,?.
If it is decided, on the basis of this test, that a between-test-result range is an outlier and is to be excluded, then the two test results that give the outlying range should be excluded from the calculation of the repeatability and reproducibility standard deviations but the other test results in the cell should be retained. To assess the uncertainty of the estimate of a laboratory bias in a split-level experiment, calculate the quantity Aas defined by equation 16 of IS0 There are robust methods that combine test results within cells in a robust manner, and they would be more complicated to apply in practice.
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When this risk is considered to be serious, the split-level design described in this part of IS0 may be preferred as it reduces this risk. Intermediate measures of the precision of a standard measurement method Part 4: If a precision experiment is performed using the uniform level design described in IS0in which each laboratory is sent one hide at each level of the experiment, and two test results are obtained on each hide, variation between hides will add to the between-laboratory variation, and so increase the reproducibility standard deviation.
The data for Level 14 57255- table 4 are used here to illustrate the results that are obtained by robust analysis.
If data are rejected, recalculate the statistics. However, the above equation may be derived by replacing p in equation 9 of IS0 This website is best viewed with browser version of up to Microsoft Internet Explorer 8 or Firefox 3.
BS ISO 5725-5:1998
The robust methods described in this clause allow the data to be analysed in such a way that it is not required to make decisions that affect the results of the 525-5. International organisations, governmental and non-governmental, in liaison with ISO, also take pari in the work. This is why it is important that the two materials should be similar.
It is incorrect to use such oso 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. In the leather example discussed in 5.
ISO Accuracy of Measurement Methods and Results Package
The solution may also be derived directly, as follows. With heterogeneous materials this may not be isp, so that the use of the basic method then gives estimates of the reproducibility standard deviation that are inflated by the variation between the samples. This does not raise any issues isl have not already been covered in IS0so it will not be considered here. Learn more about the cookies we use and how to change your settings.