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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Please first verify your email before subscribing to alerts. If a laboratory is achieving poor repeatability then it will give unusually large k statistics in the graph that is derived from the be? The basic method requires the preparation of a number of identical samples of the material for use in the experiment. Calculation of the sum of squares for repeatability 6 Robust methods for data analysis 6.
A design for a heterogeneous material This is strong evidence that there are consistent biases in most laboratories, indicating that the test method is not adequately specified. Probability and general isoo terms. 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. 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 izo, followed by drying.
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ISO Accuracy of Measurement Methods and Results Package
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Note that q depends on the degrees of freedom of s. Graphs of this type give an easily understood picture of the amount of variation arising from the different sources between test results, between samples, and between ixo.
They are used to identify results that are so inconsistent with the remainder of the data 57255- in 5725- experiment that their inclusion in the calculation of the repeaiability and reproducibility standard deviations would affect the values of these statistics substantially.
Calculate the cell averages yii and enter them into a table as shown in table 3. All standards are subject to revision, and parties to agreements based on this part of IS0 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.
BS ISO 5725-5:1998
Some participants in a precision experiment may achieve poor repeatability when a measurement method is subjected to a precision experiment for the first time, or when they have little experience of the measurement method, and these are situations when the use of robust methods will be particularly appropriate.
Hence, as with leather, if a uniform level experiment is performed in which each laboratory is sent one bulk sample at each level, the variability between the bulk samples will increase the calculated reproducibility standard deviation of the test method, lso if laboratories are sent two bulk samples at each level, then values for the reproducibility standard deviation can be calculated that exclude this variation. For an experiment with a heterogeneous material, this model is expanded to become: The number of replicates, n in IS0may be taken to be the number of split-levels in a split-level design,?.
Table 2 – Recommended form for tabulation of cell differencesfor the split-level design Laboratory 1 1 2 I! This part of IS0 complements IS0 by providing alternative designs that may be of more value in some situations than the basic design given in IS0and by providing a robust method of analysis that gives 57225-5 of the repeatability and reproducibility standard deviations that are less dependent on the data analyst’s judgement than those given by the methods iwo in IS0 Already Subscribed to this document.
Basic method for the determination of repeatability and reproducibility of a standard measurement method Part 3: Methods for determination of soundness. The sample effects for each i and r with summation over k: This standard is also available to be included in Standards Subscriptions.
To show up inconsistent laboratories, plot both sets of these statistics in the order of the levels, but grouped by laboratory, as shown in 5725–5 2 and 3. Robust statistics – How not to reject outliers.
In these figures, the levels have been re-arranged so that the general averages are in increasing order – as shown in table Examine the data for consistency using the h and k statistics, described in subclause 7.
This figure thus provides a case for investigatingthe causes of the biases at the three laboratories. The general average with summation over irand k: It yields a robust pooled value of the standard deviations or ranges to which it is applied. The derivation of the factors used in algorithm S is set out below. Accept and continue Learn more about the cookies we use and how to change your settings. Also in this design, the cell standard deviations are pooled to give an estimate iwo the repeatability standard deviation.
NOTES 1 It may be of interest to perform a significance test to see if the variation between samples is statistically significant, however, this is not a necessary part of the analysis. Page 38, Equation 72 in Subclause 6. The interpretation of these graphs is discussed fully in subclause 7.
The first term on the right-handside of equation 8. The corresponding formulae for the split-level experiment are set out below. 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 figure 3, the h statistics for cell averages show that Laboratory 5 gave negative h statistics at all levels, indicating a consistent negative bias in their data.