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1、i. I t JIS JAPANESE IN DUSTRIAL STANDARD Translated and Published by Japanese Standards Association (IS0 5725-6 : 1994) Accuracy (trueness and precision) of measurement methods and results - Part 6: Use in practice of accuracy values ICs 03.120.30 ; 17.020 Descriptors : measurement, datum, precision
2、, accuracy, reproducibility Reference number : JIS Z 8402-6 : 1999 (E) 29 S Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 20:54:14 MDTNo reproduction or networking permitted without licen
3、se from IHS -,-,- Z 8402-6 : 1999 (IS0 5725-61994) Foreword This translation has been made based on the original Japanese Industrial Standard established by the Minister of International Trade and Industry through deliberations at the Japanese Industrial Standards Committee in accordance with the In
4、dustrial Standardization Law. By this establishment, JIS Z 8402 : 1991 was withdrawn and replaced with this Standard. This Standard has been prepared based on the first edition of IS0 5725- 6 issued in 1994. JIS Z 8402 : 1999 consists of the following 6 parts under the title “Accuracy (trueness and
5、precision) of measurement methods and results”. Part 1 : Part 2: Part 3: Part 4: Part 5: Part 6: General principles and definitions Basic method for the determination of repeatability and reproducibility of a standard measurement method Intermediate measures of the precision of a standard measuremen
6、t method Basic methods for the determination of the trueness of a standard measurement method Alternative methods for the determination of the precision of a standard measurement method Use in practice of accuracy values Date of Establishment: 1999-05-20 Date of Public Notice in Official Gazette: 19
7、99-05-20 Investigated by: Japanese Industrial Standards Committee Divisional Council on Basic Items JIS Z 8402-6 : 1999, First English edition published in 2001-01 Translated and published by: Japanese Standards Association 4-1-24, Akasaka, Minato-ku, Tokyo, 107-8440 JAPAN In the event of any doubts
8、 arising as to the contents, the original JIS is to be the final authority. P I JSA2001 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without perm
9、ission in writing from the publisher. Printed in Japan Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 20:54:14 MDTNo reproduction or networking permitted without license from IHS -,-,- 2 8
10、402-6 : 1999 (IS0 5725-6 : 1994) Contents Page . Introduction 1 1 Scope 1 2 Normative references 2 3 Definitions 3 4 Determination of limits 3 4? 1 Repeatability and reproducibility limits 3 4.2 Comparisons based on more than two values. 4 . . . 5 Methods for checking the acceptability of test resul
11、ts and . determining the final quoted result 5 5.1 General 5 5.2 Methods for checking the acceptability of . test results obtained under repeatability conditions . 6 test results obtained under both repeatability and reproducibility conditions . 12 5.3 Methods for checking the acceptability of 6 Met
12、hod for checking the stability of test results within a laboratory 15 6.1 Background 15 6. 2 Methods for checking stability 17 7 Use o f repeatability and reproducibility standard deviations in assessing laboratories 29 29 . 7.1 Assessment method 7.2 Evaluation of the use of a measurement method by
13、a laboratory not previously assessed . 30 7.3 8 Comparison of altemative measurement methods 40 Continued assessment of previously approved laboratories 34 . Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Re
14、sale, 03/12/2007 20:54:14 MDTNo reproduction or networking permitted without license from IHS -,-,- i.i733b08 05b7085 O32 H JAPANESE INDUSTRIAL STANDARD JIS Z 8402-6 : 1999 ( I S 0 5725-6: 1994) Accuracy (trueness and precision) of measurement methods and results - Part 6: Use in practice of accurac
15、y values Introduction This Japanese Industrial Standard has been prepared based on IS0 5725-6 Accuracy (trueness and precision) of measurement methods and results - Part 6 : Use in practice of accuracy values issued in 1994 as the first edition without changing the technical contents. The “Informati
16、ve references” underlined with dots in this Standard show the matters not specified in the original International Standard. 0.1 JIS Z 8402 uses two terms “trueness” and “precision” to describe the accuracy of a measurement method. “Trueness” refers to the closeness of agreement between the arithmeti
17、c mean of a large number of test results and the true or accepted reference value. “Precision” refers to the closeness of agreement between test results. 0.2 The need to consider “precision” arises because tests performed on presumably identical materials in presumably identical circumstances do not
18、, in general, yield identical results. This is attributed to unavoidable random errors inherent in every measurement procedure; the factors that influence the outcome of a measurement cannot all be completely controlled. In the practical interpretation of measurement data, this variability has to be
19、 taken into account. For instance, the difference between a test result and some specified value may be within the scope of unavoidable random errors, in which case a real deviation from such a specified value has not been established. Similarly, comparing test results from two batches of material w
20、ill not indicate a fundamental quality difference if the difference between them can be attributed to the inherent variation in the measurement procedure. O 3 Parts 1 to 5 of JIS Z 8402 dicuss the background to, and given methods for, the assessment of the precision (in terms of the repeatability st
21、andard deviation and the reproduc- ibility standard deviation) and the trueness (in terms of the various components of bias) of measurements produced by a standard measurement method. Such assessment would, how- ever, be pointless if there were no practical uses to which the results could be put. 0.
22、4 Given that the accuracy of a measurement method has been established, this part of JIS Z 8402 applies that knowledge in practical situations in such a way as to facilitate commer- cial transactions and to monitor and improve the operational performance of laboratories. 1 Scope 1.1 accuracy data ca
23、n be used in various practical situations by : The purpose of this part of JIS Z 8402 is to give some indications of the way in which a) giving a standard method of calculating the repeatability limit, the reproducibility limit and other limits to be used in examining the test results obtained by a
24、standard measurement method ; Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 20:54:14 MDTNo reproduction or networking permitted without license from IHS -,-,- 4733b08 05b70b T77 m 2 Z 840
25、2-6 : 1999 (IS0 5725-6 : 1994) providing a way of checking the acceptability of test results obtained under repeatability or reproducibility conditions ; describing how to assess the stability of results within a laboratory over a period of time, and thus providing a method of “quality control” of t
26、he operations within that laboratory ; describing how to assess whether a given laboratory is able to use a given standard measurement method in a satisfactory way ; describing how to compare alternative measurement methods. 1.2 This part of JIS 2 8402 is concerned exclusively with measurement metho
27、ds which yield measurements on a continuous scale and give a single numerical figure as the result, although this single figure may be the outcome of a calculation from a set of observations. 1.3 It is assumed that the estimates of trueness and precsion for the method have been obtained in accordanc
28、e with parts 1 to 5 of JIS Z 8402. 1.4 Any additional information regarding the field of application will be given at the beginning of each particular application. 2 Normative references The following standards contain provisions which, through reference in this Standard, constitute provisions of th
29、is Standard. If the indication of the year of coming into effect is given to these referred standards, only the edition of indicated year constitutes the provision of this Standard but the revision and amendment made thereafter are not applied. The normative references without the indication of the
30、year of coming into effect apply limiting only to the most recent edition (including the amendment). JIS Q 0033 : 1997 JIS Q 0035 : 1997 JIS Z 8101-1 JIS Z 8101-2 JIS Z 8402-1 : 1999 JIS Z 8402-2 : 1999 JIS Z 8402-3: 1999 JIS Z 8402-4 : 1999 Uses of certified reference materials Certification o f re
31、ference materials - General and statistical principles Statistics - Vocabulary and symbols -Part 1 : Probability and general statistical terms Statistics - Vocabulary and symbols - Part 2 : Statistical qual- ity control Accuracy (trueness and precision) of measurement methods and results - Part 1 :
32、General principles and definitions Accuracy (trueness and precision) of measurement methods and results - Part 2 : Basic method for the determination o f repeat- ability and reproducibility of a standard measurement method Accuracy (trueness and precision) o f measurement methods and results-Part 3:
33、 Intermediate measures o f the precision o f a standard measurement method Accuracy (trueness and precision) o f measurement methods and results - Part 4 : Basic methods for the determination o f the trueness o f a standard measurement method Shewhart control charts 1 I Copyright Japanese Standards
34、Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 20:54:14 MDTNo reproduction or networking permitted without license from IHS -,-,- J I S Z 9325: 1996 General requirements for the competence of calibration and testing l
35、aboratories 3 Definitions For the purposes of this part of JIS Z 8402, the definitions given in JIS 2 8101 and JIS 2 8402-1 apply. The symbols used in JIS Z 8402 are given in Annex A. 4 Determination of limits 4.1 Repeatability and reproducibility limits 4.1.1 In JIS Z 8402-2, attention has been foc
36、ussed on estimating the standard deviations associated with operations under repeatability or reproducibility conditions. However, normal laboratory practice requires examination of the differences (s) observed between two (or more) test results, and for this purpose some measure akin to a critical
37、difference is required, rather than a standard deviation. 4.1.2 When a quantity is based on sums or differences of n independent estimates each having a standard deviation u, then that resultant quantity will have a standard deviation a h . The reproducibility limit (R) or repeatability limit ( r )
38、are for differences between two test results, so the associated standard deviation is afl. In normal statistical practice, for examining the difference between these two values the critical difference used is f times this standard deviation, Le. fufl. The value of f (the critical range factor) depen
39、ds on the probability level to be associated with the critical difference and on the shape of the underlying distribution. For the reproducibility and repeatability limits, the probability level is specified as 95 %, and throughout the analysis in JIS Z 8402 the assumption is made that the underlyin
40、g distribution is approximately normal. For a normal distribution at 95 % probability level, fis 1.96 and fa then is 2.77. As the purpose of this part of JIS Z 8402 is to give some simple ?rule of thumb? to be applied by non-statisticians when examining the results of tests, it seems reasonable to u
41、se a rounded value of 2.8 instead of fJz . 4.1.3 As has been stated, the process of estimating precision leads to estimates of the true standard deviations while the true standard deviations remain unknown. Therefore in statis- tical practice they should be denoted by s rather than u. However, if th
42、e procedures given in JIS Z 8402-1 and JIS Z 8402-2 are followed, these estimates will be based on an appre- ciable number of test results, and will give the best information we are likely to have of the true values of the standard deviations. In other applications that follow, for estimates of thes
43、e standard deviations based on more limited data, the symbol s (estimate of a standard deviation) is used. Therefore it seems best to use the symbol u to denote the values obtained from a full precision experiment, and treat these as true standard deviations with which other estimates ( s ) will be
44、compared. 4.1.4 In view of 4.1.1 to 4.1.3, when examining two single test results obtained under repeatability or reproducibility conditions, the comparison shall be made with the repeat- ability limit Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employ
45、ees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 20:54:14 MDTNo reproduction or networking permitted without license from IHS -,-,- 4 Z 8402-6 : 1999 (IS0 5725-6 : 1994) or the reproducibility limit. R = 2 . 8 4.2 Comparisons based on more than two values 4.2.1 Two groups of measurements
46、 in one laboratory If, in one laboratory under repeatability conditions, two groups of measurements are performed with the first group ofn, test results giving an arithmetic mean of YI and the second group of n2 test results giving an arithmetic mean of Y 2 , then the standard deviation of ( Y I - Y
47、,) is - - and the critical difference for lyl -y21 is at the 95 % probability level. Note 1 If nl and n2 are both unity, this reduces to r = 2-8ar2 as expected. 4.2.2 Two groups of measurements in two laboratories If the first laboratory obtains nl test results giving an arithmetic mean of YI while
48、the second laboratory obtains n2 test results giving an arithmetic mean of i 2 , in each case under repeatability conditions, then the standard deviation of ( Y I - gz) is = Jz(at+a:) -2 and -whether the arithmetic mean or the median of the test results was taken. S t a r t with n results Arithmetic
49、 mean of ail n results is the final quoted result Range of n results S CR, (n) obtain mi) further results ; Arithmetic mean of all (n + m) results is the final quoted result Median of all (n + m) results is the final quoted result i) m has to be chosen as an integer safsfying the condition n13 Sm O n12 Fig. 6 Method for chec