1、Designation: D6300 15 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 the year
2、 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:D02-1007,2Manual on Determining
3、Precision Data for ASTM Methodson Petroleum Products and Lubricants2and 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 encompasses both
4、the determination of precision and the application of such precisiondata. In effect, it combines the type of information in RR:D02-10072regarding the determination ofthe precision estimates and the type of information in Practice D3244 for the utilization of test data.The following practice, intende
5、d to replace RR:D02-1007,2differs slightly from related portions of theISO standard.1. Scope*1.1 This practice covers the necessary preparations andplanning for the conduct of interlaboratory programs for thedevelopment of estimates of precision (determinability,repeatability, and reproducibility) a
6、nd of bias (absolute andrelative), and further presents the standard phraseology forincorporating such information into standard test methods.1.2 This practice is generally limited to homogeneous prod-ucts with which serious sampling problems do not normallyarise.1.3 This practice may not be suitabl
7、e for solid or semisolidproducts such as petroleum coke, industrial pitches, paraffinwaxes, greases, or solid lubricants when the heterogeneousproperties of the substances create sampling problems. In suchinstances, use Practice E691 or consult a trained statistician.2. Referenced Documents2.1 ASTM
8、Standards:3D3244 Practice for Utilization of Test Data to DetermineConformance with SpecificationsD3606 Test Method for Determination of Benzene andToluene in Finished Motor and Aviation Gasoline by GasChromatographyD6708 Practice for Statistical Assessment and Improvementof Expected Agreement Betwe
9、en Two Test Methods thatPurport to Measure the Same Property of a MaterialD7915 Practice for Application of Generalized ExtremeStudentized Deviate (GESD) Technique to Simultane-ously Identify Multiple Outliers in a Data SetE29 Practice for Using Significant Digits in Test Data toDetermine Conformanc
10、e with SpecificationsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standards:ISO 4259 Petroleum Products-Determination
11、 and Applica-tion of Precision Data in Relation to Methods of Test43. Terminology3.1 Definitions:3.1.1 analysis of variance (ANOVA), ntechnique that en-ables the total variance of a method to be broken down into itscomponent factors. ISO 42591This practice is under the jurisdiction of ASTM Committee
12、 D02 on PetroleumProducts, Liquid Fuels, and Lubricantsand is the direct responsibility of Subcom-mittee D02.94 on Coordinating Subcommittee on Quality Assurance and Statistics.Current edition approved June 1, 2015. Published June 2015. Originallyapproved in 1998. Last previous edition approved in 2
13、014 as D6300 14a1. DOI:10.1520/D6300-15.2Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1007.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annua
14、l Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.*A Summary of Changes section appears at the end of this standard
15、Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.2 bias, nthe difference between the expectation of thetest results and an accepted reference value.3.1.2.1 DiscussionThe term “expectation” is used in thecontext of statistics termin
16、ology, which implies it is a “statis-tical expectation.” E1773.1.3 between-method bias (relative bias), na quantitativeexpression for the mathematical correction that can statisticallyimprove the degree of agreement between the expected valuesof two test methods which purport to measure the sameprop
17、erty. D67083.1.4 degrees of freedom, nthe divisor used in the calcu-lation of variance, one less than the number of independentresults.3.1.4.1 DiscussionThis definition applies strictly only inthe simplest cases. Complete definitions are beyond the scopeof this practice. ISO 42593.1.5 determinabilit
18、y, na quantitative measure of the vari-ability associated with the same operator in a given laboratoryobtaining successive determined values using the same appa-ratus for a series of operations leading to a single result; it isdefined as that difference between two such single determinedvalues as wo
19、uld be exceeded in the long run in only one casein 20 in the normal and correct operation of the test method.3.1.5.1 DiscussionThis definition implies that two deter-mined values, obtained under determinability conditions,which differ by more than the determinability value should beconsidered suspec
20、t. If an operator obtains more than twodeterminations, then it would usually be satisfactory to checkthe most discordant determination against the mean of theremainder, using determinability as the critical difference (1).53.1.6 mean square, nin analysis of variance, sum ofsquares divided by the deg
21、rees of freedom. ISO 42593.1.7 normal distribution, nthe distribution that has theprobability function x, such that, if x is any real number, theprobability density isfx! 5 1/!2!21/2exp2x 2 !2/22# (1)NOTE 1 is the true value and is the standard deviation of thenormal distribution ( 0). ISO 42593.1.8
22、 outlier, na result far enough in magnitude from otherresults to be considered not a part of the set. RR:D02100723.1.9 precision, nthe degree of agreement between two ormore results on the same property of identical test material. Inthis practice, precision statements are framed in terms ofrepeatabi
23、lity and reproducibility of the test method.3.1.9.1 DiscussionThe testing conditions represented byrepeatability and reproducibility should reflect the normalextremes of variability under which the test is commonly used.Repeatability conditions are those showing the least variation;reproducibility,
24、the usual maximum degree of variability. Referto the definitions of each of these terms for greater detail.RR:D02100723.1.10 random error, nthe chance variation encountered inall test work despite the closest control of variables.RR:D02100723.1.11 repeatability, nthe quantitative expression of thera
25、ndom error associated with the same operator in a givenlaboratory obtaining repetitive results by applying the same testmethod with the same apparatus under constant operatingconditions on identical test material within short intervals oftime. It is defined as the difference between two such results
26、 atthe 95 % confidence level. RR:D02100723.1.11.1 DiscussionInterpret as the value equal to orbelow which the absolute difference between two single testresults obtained in the above conditions may expect to lie witha probability of 95 %. ISO 42593.1.11.2 DiscussionThe difference is related to the r
27、epeat-ability standard deviation but it is not the standard deviation orits estimate. RR:D02100723.1.12 reproducibility, na quantitative expression of therandom error associated with different operators from differentlaboratories using different apparatus, each obtaining a singleresult by applying t
28、he same test method on an identical testsample. It is defined as the 95 % confidence limit for thedifference between two such single and independent results.3.1.12.1 DiscussionInterpret as the value equal to orbelow which the absolute difference between two single testresults on identical material o
29、btained by operators in differentlaboratories, using the standardized test, may be expected to liewith a probability of 95 %. ISO 42593.1.12.2 DiscussionThe difference is related to the repro-ducibility standard deviation but is not the standard deviationor its estimate. RR:D02100723.1.12.3 Discussi
30、onIn those cases where the normal useof the test method does not involve sending a sample to atesting laboratory, either because it is an in-line test method orbecause of serious sample instabilities or similar reasons, theprecision test for obtaining reproducibility may allow for theuse of apparatu
31、s from the participating laboratories at acommon site (several common sites, if feasible). The statisticalanalysis is not affected thereby. However, the interpretation ofthe reproducibility value will be affected, and therefore, theprecision statement shall, in this case, state the conditions towhic
32、h the reproducibility value applies.3.1.13 standard deviation, nmeasure of the dispersion of aseries of results around their mean, equal to the square root ofthe variance and estimated by the positive square root of themean square. ISO 42593.1.14 sum of squares, nin analysis of variance, sum ofsquar
33、es of the differences between a series of results and theirmean. ISO 42593.1.15 variance, na measure of the dispersion of a seriesof accepted results about their average. It is equal to the sum ofthe squares of the deviation of each result from the average,divided by the number of degrees of freedom
34、. RR:D02100723.1.16 variance, between-laboratory, nthat component ofthe overall variance due to the difference in the mean valuesobtained by different laboratories. ISO 42593.1.16.1 DiscussionWhen results obtained by more than5The bold numbers in parentheses refers to the list of references at the e
35、nd of thisstandard.D6300 152one laboratory are compared, the scatter is usually wider thanwhen the same number of tests are carried out by a singlelaboratory, and there is some variation between means obtainedby different laboratories. Differences in operator technique,instrumentation, environment,
36、and sample “as received” areamong the factors that can affect the between laboratoryvariance. There is a corresponding definition for between-operator variance.3.1.16.2 DiscussionThe term “between-laboratory” is of-ten shortened to “laboratory” when used to qualify represen-tative parameters of the
37、dispersion of the population of results,for example as “laboratory variance.”3.2 Definitions of Terms Specific to This Standard:3.2.1 determination, nthe process of carrying out a seriesof operations specified in the test method whereby a singlevalue is obtained.3.2.2 operator, na person who carries
38、 out a particular test.3.2.3 probability density function, nfunction which yieldsthe probability that the random variable takes on any one of itsadmissible values; here, we are interested only in the normalprobability.3.2.4 result, nthe final value obtained by following thecomplete set of instructio
39、ns in the test method.3.2.4.1 DiscussionIt may be obtained from a single deter-mination or from several determinations, depending on theinstructions in the method. When rounding off results, theprocedures described in Practice E29 shall be used.4. Summary of Practice4.1 A draft of the test method is
40、 prepared and a pilotprogram can be conducted to verify details of the procedureand to estimate roughly the precision of the test method.4.1.1 If the responsible committee decides that an interlabo-ratory study for the test method is to take place at a later pointin time, an interim repeatability is
41、 estimated by following therequirements in 6.2.1.4.2 A plan is developed for the interlaboratory study usingthe number of participating laboratories to determine thenumber of samples needed to provide the necessary degrees offreedom. Samples are acquired and distributed. The interlabo-ratory study i
42、s then conducted on an agreed draft of the testmethod.4.3 The data are summarized and analyzed. Any depen-dence of precision on the level of test result is removed bytransformation. The resulting data are inspected for uniformityand for outliers. Any missing and rejected data are estimated.The trans
43、formation is confirmed. Finally, an analysis of vari-ance is performed, followed by calculation of repeatability,reproducibility, and bias. When it forms a necessary part of thetest procedure, the determinability is also calculated.5. Significance and Use5.1 ASTM test methods are frequently intended
44、 for use inthe manufacture, selling, and buying of materials in accordancewith specifications and therefore should provide such precisionthat when the test is properly performed by a competentoperator, the results will be found satisfactory for judging thecompliance of the material with the specific
45、ation. Statementsaddressing precision and bias are required in ASTM testmethods. These then give the user an idea of the precision ofthe resulting data and its relationship to an accepted referencematerial or source (if available). Statements addressing deter-minability are sometimes required as par
46、t of the test methodprocedure in order to provide early warning of a significantdegradation of testing quality while processing any series ofsamples.5.2 Repeatability and reproducibility are defined in theprecision section of every Committee D02 test method. Deter-minability is defined above in Sect
47、ion 3. The relationshipamong the three measures of precision can be tabulated interms of their different sources of variation (see Table 1).5.2.1 When used, determinability is a mandatory part of theProcedure section. It will allow operators to check theirtechnique for the sequence of operations spe
48、cified. It alsoensures that a result based on the set of determined values isnot subject to excessive variability from that source.5.3 Abias statement furnishes guidelines on the relationshipbetween a set of test results and a related set of acceptedreference values. When the bias of a test method i
49、s known, acompensating adjustment can be incorporated in the testmethod.5.4 This practice is intended for use by D02 subcommitteesin determining precision estimates and bias statements to beused in D02 test methods. Its procedures correspond with ISO4259 and are the basis for the Committee D02 computersoftware, Calculation of Precision Data: Petroleum Test Meth-ods. The use of this practice replaces that of Research ReportRR:D02-1007.25.5 Standard practices for the calculation of precision havebeen written by many committees wit
