ASTM_E_2480_-_12.pdf

Designation:E248012Standard Practice forConducting an Interlaboratory Study to Determine thePrecision of a Test Method with Multi-Valued Measurands1This standard is issued under the fixed designation E2480;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.1.Scope1.1 This practice describes the techniques for planning,conducting,and analyzing the results of an interlaboratorystudy(ILS)conducted for certain test methods within Com-mittee E12.1.2 This practice does not concern itself with the develop-ment of the test method but rather with the gathering of theinformation needed for the precision and bias statement afterthe completion of development of the test method.The dataobtained in the ILS may indicate,however,that further effort isneeded to improve the test method.1.3 This practice is concerned exclusively with test methodsthat derive a multi-valued measurand,such as,but not limitedto,spectral reflectance,transmittance function,tristimulusvalues,or RGB values.Variation in measurements of suchmulti-valued measurands are usually analyzed by reducing thedata to a single-valued parameter,such as color difference,E.1.4 This practice covers methods of dealing with the non-normal distribution of the variation of sets of color-differences.This is done so that the user may derive valid statistics fromsuch non-normal distributions.1.5 This practice does not cover test methods,even inCommittee E12,whose measurands are single-valued,orwhose variations are known to be normally distributed.Taskgroups involved with such test methods are referred to PracticeE691 which contains preferable methods of analyzing datawith those properties.1.6 This practice is not intended to establish a method forestimating possible color-difference tolerances.1.7 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.8 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE284 Terminology of AppearanceE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1345 Practice for Reducing the Effect of Variability ofColor Measurement by Use of Multiple Measurements3.Terminology3.1 DefinitionsFor color and appearance terms,see Ter-minology E284.3.2 Definitions of Terms Specific to This Standard:3.2.1 precision and bias,nwhen a test method is appliedto a large number of specimens that are as nearly alike aspossible,the test results obtained nevertheless will not all havethe same values.A measure of the degree of agreement amongthese test results describes the precision of the test method forthat material.This practice is designed only to estimate theprecision of a test method.However,when accepted referencevalues are known for the materials being tested,the test resultdata obtained in accordance with this practice may be used toestimate the bias of the test method.For a discussion of biasestimation,see Practice E177.3.2.2 repeatability and reproducibility,nthe term repeat-ability concerns the variability between independent test resultsobtained within a single laboratory in the shortest practicalperiod of time by a single operator applying the test methodwith a specific set of test apparatus using test specimens takenat random from a single quantity of homogeneous materialobtained,or prepared,for the ILS.The term reproducibilityconcerns the variability between single test results obtained in1This practice is under the jurisdiction of ASTM Committee E12 on Color andAppearance and is the direct responsibility of Subcommittee E12.02 on Spectro-photometry and Colorimetry.Current edition approved July 1,2012.Published August 2012.Originallyapproved in 2007.Last previous edition approved in 2007 as E2480 07.DOI:10.1520/E2480-12.2For referenced ASTM standards,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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 different laboratories,each by a different operator,each ofwhom has applied the test method to specimens taken atrandom from a single quantity of homogeneous materialobtained,or prepared,for the ILS.3.2.2.1 DiscussionThe above single operator and singleapparatus requirement,as specified in 3.2.2,means that for aparti