1、Designation: D6300 14 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:3D123 Terminology Relating to TextilesD3244 Practice for Utilization of Test Data to DetermineConformance with SpecificationsD3606 Test Method for Determination of Benzene andToluene in Finished Motor and Aviation Gasoline by GasChromatographyE29 Practice for Using Significant Digits in Te
9、st Data toDetermine Conformance with SpecificationsE456 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 and Applica-tion of Precision Data in Rela
10、tion to Methods of Test43. Terminology3.1 Definitions:3.1.1 analysis of variance (ANOVA), na procedure fordividing the total variation of a set of data into two or moreparts, one of which estimates the error due to selecting andtesting specimens and the other part(s) possible sources ofadded variati
11、on. D1233.1.2 bias, nthe difference between the population meanof the test results and an accepted reference value. E4563.1.3 bias, relative, nthe difference between the popula-tion mean of the test results and an accepted reference value,which is the agreed upon value obtained using an acceptedrefe
12、rence method for measuring the same property.1This practice is under the jurisdiction of ASTM Committee 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 appr
13、oved May 1, 2014. Published July 2014. Originally approvedin 1998. Last previous edition approved in 2013 as D6300 13a. DOI: 10.1520/D6300-14.2Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1007.3For referenced ASTM standard
14、s, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from International Organization for Standardization, 1 rue deVaremb, Case posta
15、le 56, CH-1211 Geneva 20, Switzerland.*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 States13.1.4 degrees of freedom, nthe divisor used in the calcu-lation of variance.3.1.4.1
16、 DiscussionThis definition applies strictly only inthe simplest cases. Complete definitions are beyond the scopeof this practice. ISO 42593.1.5 determinability, na quantitative measure of the vari-ability associated with the same operator in a given laboratoryobtaining successive determined values u
17、sing 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 would 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
18、 implies that two deter-mined values, obtained under determinability conditions,which differ by more than the determinability value should beconsidered suspect. If an operator obtains more than twodeterminations, then it would usually be satisfactory to checkthe most discordant determination against
19、 the mean of theremainder, using determinability as the critical difference (1).53.1.6 mean square, n in analysis of variance, a contrac-tion of the expression “mean of the squared deviations from theappropriate average(s)” where the divisor of each sum ofsquares is the appropriate degrees of freedo
20、m. D1233.1.7 normal distribution, nthe distribution that has theprobability function:fx! 5 1/!2!21/2exp2x 2 !2/22# (1)where:x = a random variate, = the mean distribution, and = the standard deviation of the distribution.(Syn. Gaussian distribution, law of error) D1233.1.8 outlier, na result far enou
21、gh 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 ofrepeatability and reproducibility of
22、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, the usual maximum degree of
23、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 therandom error associated with t
24、he 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 atthe 95 % confidence level
25、. 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 repeat-ability standard devia
26、tion 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 the same test method on an id
27、entical 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 obtained by operators in diff
28、erentlaboratories, 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 DiscussionIn those cases where the n
29、ormal 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 apparatus from the participating lab
30、oratories 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 towhich the reproducibility value
31、applies.3.1.13 standard deviation, nthe most usual measure of thedispersion of observed values or results expressed as thepositive square root of the variance. E4563.1.14 sum of squares, nin analysis of variance, a con-traction of the expression “sum of the squared deviations fromthe appropriate ave
32、rage(s)” where the average(s) of interestmay be the average(s) of specific subset(s) of data or of theentire set of data. D1233.1.15 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 th
33、e average,divided by the number of degrees of freedom. 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 thanone laboratory are co
34、mpared, 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, and sample “as received” are5The bold numbers in
35、parentheses refers to the list of references at the end of thisstandard.D6300 142among 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” wh
36、en used to qualify represen-tative parameters of the 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 singleva
37、lue is obtained.3.2.2 operator, na person who carries 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 valu
38、e obtained by following thecomplete set of instructions 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.
39、 Summary of Practice4.1 A draft of the test method is prepared and a pilotprogram can be conducted to verify details of the procedureand to estimate roughly the precision of the test method.4.2 A plan is developed for the interlaboratory study usingthe number of participating laboratories to determi
40、ne thenumber of samples needed to provide the necessary degrees offreedom. Samples are acquired and distributed. The interlabo-ratory study is 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 rem
41、oved bytransformation. The resulting data are inspected for uniformityand for outliers. Any missing and rejected data are estimated.The transformation is confirmed. Finally, an analysis of vari-ance is performed, followed by calculation of repeatability,reproducibility, and bias. When it forms a nec
42、essary part of thetest procedure, the determinability is also calculated.5. Significance and Use5.1 ASTM test methods are frequently intended for use inthe manufacture, selling, and buying of materials in accordancewith specifications and therefore should provide such precisionthat when the test is
43、properly performed by a competentoperator, the results will be found satisfactory for judging thecompliance of the material with the specification. Statementsaddressing precision and bias are required in ASTM testmethods. These then give the user an idea of the precision ofthe resulting data and its
44、 relationship to an accepted referencematerial or source (if available). Statements addressing deter-minability are sometimes required as part of the test methodprocedure in order to provide early warning of a significantdegradation of testing quality while processing any series ofsamples.5.2 Repeat
45、ability and reproducibility are defined in theprecision section of every Committee D02 test method. Deter-minability is defined above in Section 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, de
46、terminability is a mandatory part of theProcedure section. It will allow operators to check theirtechnique for the sequence of operations specified. It alsoensures that a result based on the set of determined values isnot subject to excessive variability from that source.5.3 Abias statement furnishe
47、s guidelines on the relationshipbetween a set of test results and a related set of acceptedreference values. When the bias of a test method is known, acompensating adjustment can be incorporated in the testmethod.5.4 This practice is intended for use by D02 subcommitteesin determining precision esti
48、mates and bias statements to beused in D02 test methods. Its procedures correspond with ISO4259 and are the basis for the Committee D02 computersoftware, Calculation if Precision Data: Petroleum Test Meth-ods. The use of this practice replaces that of Research ReportRR:D02-1007.25.5 Standard practic
49、es for the calculation of precision havebeen written by many committees with emphasis on theirparticular product area. One developed by Committee E11 onStatistics is Practice E691. Practice E691 and this practicediffer as outlined in Table 2.6. Stages in Planning of an Interlaboratory Test Programfor the Determination of the Precision of a TestMethod6.1 The stages in planning an interlaboratory test programare: preparing a draft method of test (see 6.2), planning andexecuting a pilot program with at least two laboratories(optional bu
