1、Designation: D6300 15D6300 16 An American National StandardStandard Practice forDetermination of Precision and Bias Data for Use in TestMethods for Petroleum Products and Lubricants1This standard is issued under the fixed designation D6300; the number immediately following the designation indicates
2、the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONBoth Research Report RR:D02-1007,2 Manual on Det
3、ermining Precision Data for ASTM Methodson Petroleum Products and Lubricants2 and the ISO 4259, benefitted greatly from more than 50 yearsof collaboration between ASTM and the Institute of Petroleum (IP) in the UK. The more recent workwas documented by the IP and has become ISO 4259.ISO 4259 encompa
4、sses both the determination of precision and the application of such precisiondata. In effect, it combines the type of information in RR:D02-10072 regarding the determination ofthe precision estimates and the type of information in Practice D3244 for the utilization of test data.The following practi
5、ce, intended to replace RR:D02-1007,2 differs slightly from related portions of theISO standard.1. Scope*1.1 This practice covers the necessary preparations and planning for the conduct of interlaboratory programs for thedevelopment of estimates of precision (determinability, repeatability, and repr
6、oducibility) and of bias (absolute and relative), andfurther presents the standard phraseology for incorporating such information into standard test methods.1.2 This practice is generally limited to homogeneous products with which serious sampling problems do not normally arise.1.3 This practice may
7、 not be suitable for solid or semisolid products such as petroleum coke, industrial pitches, paraffin waxes,greases, or solid lubricants when the heterogeneous properties of the substances create sampling problems. In such instances, usePractice E691 or consult a trained statistician.2. Referenced D
8、ocuments2.1 ASTM Standards:3D3244 Practice for Utilization of Test Data to Determine Conformance with SpecificationsD3606 Test Method for Determination of Benzene and Toluene in Finished Motor and Aviation Gasoline by Gas Chromatog-raphyD6708 Practice for Statistical Assessment and Improvement of Ex
9、pected Agreement Between Two Test Methods that Purportto Measure the Same Property of a MaterialD7915 Practice for Application of Generalized Extreme Studentized Deviate (GESD) Technique to Simultaneously IdentifyMultiple Outliers in a Data SetE29 Practice for Using Significant Digits in Test Data t
10、o Determine Conformance with SpecificationsE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method1 This practice is under the jurisd
11、iction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of SubcommitteeD02.94 on Coordinating Subcommittee on Quality Assurance and Statistics.Current edition approved June 1, 2015April 1, 2016. Published June 2015April 2016. Originally approv
12、ed in 1998. Last previous edition approved in 20142015 asD6300 14aD6300 15.1. DOI: 10.1520/D6300-15.10.1520/D6300-16.2 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1007.3 For referencedASTM standards, visit theASTM websit
13、e, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication
14、of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be consider
15、ed the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.2 ISO Standards:ISO 4259 Petroleum Products-Determination and Application of Precision Data in
16、 Relation to Methods of Test43. Terminology3.1 Definitions:3.1.1 analysis of variance (ANOVA), ntechnique that enables the total variance of a method to be broken down into itscomponent factors. ISO 42593.1.2 bias, nthe difference between the expectation of the test results and an accepted reference
17、 value.3.1.2.1 DiscussionThe term “expectation” is used in the context of statistics terminology, which implies it is a “statistical expectation.” E1773.1.3 between-method bias (relative bias), na quantitative expression for the mathematical correction that can statisticallyimprove the degree of agr
18、eement between the expected values of two test methods which purport to measure the same property.D67083.1.4 degrees of freedom, nthe divisor used in the calculation of variance, one less than the number of independent results.3.1.4.1 DiscussionThis definition applies strictly only in the simplest c
19、ases. Complete definitions are beyond the scope of this practice. ISO 42593.1.5 determinability, na quantitative measure of the variability associated with the same operator in a given laboratoryobtaining successive determined values using the same apparatus for a series of operations leading to a s
20、ingle result; it is definedas that difference between two such single determined values as would be exceeded in the long run in only one case in 20 in thenormal and correct operation of the test method.3.1.5.1 DiscussionThis definition implies that two determined values, obtained under determinabili
21、ty conditions, which differ by more than thedeterminability value should be considered suspect. If an operator obtains more than two determinations, then it would usually besatisfactory to check the most discordant determination against the mean of the remainder, using determinability as the critica
22、ldifference (1).53.1.6 mean square, nin analysis of variance, sum of squares divided by the degrees of freedom. ISO 42593.1.7 normal distribution, nthe distribution that has the probability function x, such that, if x is any real number, theprobability density isfx!51/!2!21/2exp2x 2! 2/22# (1)NOTE 1
23、 is the true value and is the standard deviation of the normal distribution ( 0). ISO 42593.1.8 outlier, na result far enough in magnitude from other results to be considered not a part of the set. RR:D02100723.1.9 precision, nthe degree of agreement between two or more results on the same property
24、of identical test material. In thispractice, precision statements are framed in terms of repeatability and reproducibility of the test method.3.1.9.1 DiscussionThe testing conditions represented by repeatability and reproducibility should reflect the normal extremes of variability underwhich the tes
25、t is commonly used. Repeatability conditions are those showing the least variation; reproducibility, the usualmaximum degree of variability. Refer to the definitions of each of these terms for greater detail.RR:D02100723.1.10 random error, nthe chance variation encountered in all test work despite t
26、he closest control of variables.RR:D02100723.1.11 repeatability, nthe quantitative expression of the random error associated with the same operator in a given laboratoryobtaining repetitive results by applying the same test method with the same apparatus under constant operating conditions on4 Avail
27、able from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.5 The bold numbers in parentheses refers to the list of references at the end of this standard.D6300 162identical test material within short intervals of time. It is defined as t
28、he difference between two such results at the 95 % confidencelevel. RR:D02100723.1.11.1 DiscussionInterpret as the value equal to or below which the absolute difference between two single test results obtained in the aboveconditions may expect to lie with a probability of 95 %. ISO 42593.1.11.2 Disc
29、ussionThe difference is related to the repeatability standard deviation but it is not the standard deviation or its estimate. RR:D02100723.1.12 reproducibility, na quantitative expression of the random error associated with different operators from differentlaboratories using different apparatus, ea
30、ch obtaining a single result by applying the same test method on an identical test sample.It is defined as the 95 % confidence limit for the difference between two such single and independent results.3.1.12.1 DiscussionInterpret as the value equal to or below which the absolute difference between tw
31、o single test results on identical material obtainedby operators in different laboratories, using the standardized test, may be expected to lie with a probability of 95 %. ISO 42593.1.12.2 DiscussionThe difference is related to the reproducibility standard deviation but is not the standard deviation
32、 or its estimate. RR:D02100723.1.12.3 DiscussionIn those cases where the normal use of the test method does not involve sending a sample to a testing laboratory, either becauseit is an in-line test method or because of serious sample instabilities or similar reasons, the precision test for obtaining
33、reproducibility may allow for the use of apparatus from the participating laboratories at a common site (several common sites, iffeasible). The statistical analysis is not affected thereby. However, the interpretation of the reproducibility value will be affected,and therefore, the precision stateme
34、nt shall, in this case, state the conditions to which the reproducibility value applies.3.1.13 standard deviation, nmeasure of the dispersion of a series of results around their mean, equal to the square root of thevariance and estimated by the positive square root of the mean square. ISO 42593.1.14
35、 sum of squares, nin analysis of variance, sum of squares of the differences between a series of results and their mean.ISO 42593.1.15 variance, na measure of the dispersion of a series of accepted results about their average. It is equal to the sum of thesquares of the deviation of each result from
36、 the average, divided by the number of degrees of freedom. RR:D02100723.1.16 variance, between-laboratory, nthat component of the overall variance due to the difference in the mean valuesobtained by different laboratories. ISO 42593.1.16.1 DiscussionWhen results obtained by more than one laboratory
37、are compared, the scatter is usually wider than when the same number of testsare carried out by a single laboratory, and there is some variation between means obtained by different laboratories. Differencesin operator technique, instrumentation, environment, and sample “as received” are among the fa
38、ctors that can affect the betweenlaboratory variance. There is a corresponding definition for between-operator variance.3.1.16.2 DiscussionThe term “between-laboratory” is often shortened to “laboratory” when used to qualify representative parameters of the dispersionof the population of results, fo
39、r example as “laboratory variance.”3.2 Definitions of Terms Specific to This Standard:3.2.1 determination, nthe process of carrying out a series of operations specified in the test method whereby a single valueis obtained.D6300 1633.2.2 operator, na person who carries out a particular test.3.2.3 pro
40、bability density function, nfunction which yields the probability that the random variable takes on any one of itsadmissible values; here, we are interested only in the normal probability.3.2.4 result, nthe final value obtained by following the complete set of instructions in the test method.3.2.4.1
41、 DiscussionIt may be obtained from a single determination or from several determinations, depending on the instructions in the method. Whenrounding off results, the procedures described in Practice E29 shall be used.4. Summary of Practice4.1 Adraft of the test method is prepared and a pilot program
42、can be conducted to verify details of the procedure and to estimateroughly the precision of the test method.4.1.1 If the responsible committee decides that an interlaboratory study for the test method is to take place at a later point intime, an interim repeatability is estimated by following the re
43、quirements in 6.2.1.4.2 A plan is developed for the interlaboratory study using the number of participating laboratories to determine the number ofsamples needed to provide the necessary degrees of freedom. Samples are acquired and distributed. The interlaboratory study isthen conducted on an agreed
44、 draft of the test method.4.3 The data are summarized and analyzed. Any dependence of precision on the level of test result is removed bytransformation. The resulting data are inspected for uniformity and for outliers. Any missing and rejected data are estimated. Thetransformation is confirmed. Fina
45、lly, an analysis of variance is performed, followed by calculation of repeatability, reproducibility,and bias. When it forms a necessary part of the test procedure, the determinability is also calculated.5. Significance and Use5.1 ASTM test methods are frequently intended for use in the manufacture,
46、 selling, and buying of materials in accordance withspecifications and therefore should provide such precision that when the test is properly performed by a competent operator, theresults will be found satisfactory for judging the compliance of the material with the specification. Statements address
47、ing precisionand bias are required in ASTM test methods. These then give the user an idea of the precision of the resulting data and itsrelationship to an accepted reference material or source (if available). Statements addressing determinability are sometimesrequired as part of the test method proc
48、edure in order to provide early warning of a significant degradation of testing quality whileprocessing any series of samples.5.2 Repeatability and reproducibility are defined in the precision section of every Committee D02 test method. Determinabilityis defined above in Section 3. The relationship
49、among the three measures of precision can be tabulated in terms of their differentsources of variation (see Table 1).5.2.1 When used, determinability is a mandatory part of the Procedure section. It will allow operators to check their techniquefor the sequence of operations specified. It also ensures that a result based on the set of determined values is not subject to excessivevariability from that source.5.3 A bias statement furnishes guidelines on the relationship between a set of test results and a related set of accep
