ASTM_D_4483_-_20.pdf

Designation:D448320Standard Practice forEvaluating Precision for Test Method Standards in theRubber and Carbon Black Manufacturing Industries1This standard is issued under the fixed designation D4483;the number immediately following the designation indicates 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.INTRODUCTIONThe primary precision standard for ASTM test method standards is Practice E691;a genericstandard that presents the fundamental statistical approach and calculation algorithms for evaluatingrepeatability and reproducibility precision.However,certain parts of Practice E691 are not compatiblewith precision as evaluated in the rubber manufacturing and carbon black industries over the past fourdecades.Thus a separate standard is required for precision in these two industries.This practice isbeing issued as a major revision of Practice D4483,which has been used for precision evaluation byCommittee D11 since 1985.The basic Practice D4483 precision calculation algorithms,the same asin Practice E691,are unchanged.This new revised Practice D4483,organized to accommodate therequirements of the rubber and carbon black manufacturing industries,has three new features thatprovide for a more formal and structured analysis of interlaboratory test program(ITP)data.First it addresses the overriding issues with precision evaluation over the past several decadesthefrequent discovery that reproducibility for many test methods is quite poor.Experience has shown thatfrequently poor reproducibility is caused by only a few laboratories that differ from the remainder thatgive good agreement.A new procedure designated as robust analysis provides an improved methodfor detecting outliers that cause poor precision,especially poor between laboratory agreement.Second,after outlier detection the new standard provides two options;(1)outlier deletion or(2)outlierreplacement.When outliers are deleted the revised standard provides a way to retain the non-outlierlaboratory data.This allows for a broader database for precision calculation.The current ASTMCommittee E11 computer program for calculating precision does not allow for outlier deletion in thisway.Third,when exercising outlier Option 2,the standard gives a procedure for calculating specialreplacement values for deleted outliers in ITPs that have only a few participating laboratories.Thereplacement values are obtained in a way that preserves the observed data distribution of thenon-outlier data.This is important since many ITPs are in the limited number of participatinglaboratories category.1.Scope1.1 This practice covers guidelines for evaluating precisionand serves as the governing practice for interlaboratory testprograms(ITP)used to evaluate precision for test methods asused in the rubber manufacturing and the carbon black indus-tries.This practice uses the basic one way analysis of variancecalculation algorithms of Practice E691.Although bias is notevaluated in this practice,it is an essential concept in under-standing precision evaluation.1.2 This practice applies to test methods that have testresults expressed in terms of a quantitative continuous variable.Although exceptions may occur,it is in general limited to testmethods that are fully developed and in routine use in a numberof laboratories.1.3 Two precision evaluation methods are given that aredescribed as robust statistical procedures that attempt toeliminate or substantially decrease the influence of outliers.The first is a General Precision procedure intended for all testmethods in the rubber manufacturing industry,and the secondis a specific variation of the general precision proceduredesignated as Special Precision,that applies to carbon blacktesting.Both of these procedures use the same uniform levelexperimental design and the Mandel h and k statistics to reviewthe precision database for potential outliers.However,they use1This practice is under the jurisdiction ofASTM Committee D11 on Rubber andRubber-like Materials and is the direct responsibility of Subcommittee D11.16 onApplication of Statistical Methods.Current edition approved June 1,2020.Published June 2020.Originallyapproved in 1985.Last previous edition approved in 2018 as D4483 18.DOI:10.1520/D4483-20.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.slight modifications in the procedure for rejecting incompatibledata values as outliers.The Special Precision procedure isspecific as to the number of re