ASTM_G_117_-_13.pdf

Designation:G11713Standard Guide forCalculating and Reporting Measures of Precision UsingData from Interlaboratory Wear or Erosion Tests1This standard is issued under the fixed designation G117;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 guide covers and offers direction on the handling ofdata from interlaboratory tests for wear or erosion.It describesa format for entering data and for subsequently reportingresults on measures of precision in a Committee G02 standard.It indicates methods for calculation of the needed statisticalquantities.1.2 This guide offers guidance based on a Committee G02consensus,and exists for the purpose of emphasizing the needto use established statistical practices,and to introduce moreuniformity in reporting interlaboratory test results in Commit-tee G02 standards.1.3 An example of how the methods described in this guidemay be applied is available in personal computer format as aspreadsheet file.The purpose is to facilitate use of the methodsin this guide.The example file contains all needed equations inthe recommended format and can be edited to accept new data.Contact ASTM Headquarters or the Chairman of G02 for acopy of that computer file.The user must have spreadsheetsoftware(EXCEL or compatible)available.1.4 The methods used in this document are consistent withPractices E691 and E177.2.Referenced Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG65 Test Method for Measuring Abrasion Using the DrySand/Rubber Wheel ApparatusG76 Test Method for Conducting Erosion Tests by SolidParticle Impingement Using Gas JetsG77 Test Method for Ranking Resistance of Materials toSliding Wear Using Block-on-Ring Wear Test3.Summary of Guide3.1 Use of this guide in preparation of interlaboratory testresults for inclusion in G02 standards involves a sequence ofsteps.First the raw data from the individual laboratories areentered into a table of any suitable form that permits calcula-tion of average values and standard deviations for eachlaboratory.Then those two measures are entered,for eachlaboratory,into a table such as that shown in Fig.1.Then thesteps described in this guide are carried out,leading tocalculation of the precision measures that are to be used in thestandard being prepared.4.Significance and Use4.1 This guide is intended to assist in developing statementsof precision and supporting data that will be used in CommitteeG02 standards.The methods and approach are drawn fromPractice E177 and E691.It was felt that preparation of thisguide and its use in Committee G02 would lead to appropriatestatistical analyses and more uniformity in G02 standardsregarding reporting of interlaboratory results and precision.The guide is not meant to substitute for possible use ofPractices E177 or E691 in developing committee standards.5.Procedure5.1 An example of interlaboratory data analyzed and pre-sented in the recommended format is shown in Fig.1.The datawere obtained from an interlaboratory series of solid particleerosion tests carried out in connection with Practice G76.Thistable format can be used with either PC spreadsheet calculationor hand calculation.5.2 Data tabulation and calculation can be carried out by useof a PC and numeric spreadsheet software(for example,EXCELor compatible),as described in Table 1,or by any otherappropriate means such as hand calculation(Table 2).Theformulas were obtained from Practices E177 or E691 or fromstatistical analysis texts.Formulas that are used for calculationare given in Table 1 for spreadsheet calculation and in Table 2for hand calculation.1This guide is under the jurisdiction of ASTM Committee G02 on Wear andErosion and is the direct responsibility of Subcommittee G02.20 on Data Acquisi-tion in Tribosystems.Current edition approved Aug.1,2013.Published August 2013.Originallyapproved in 1993.Last previous edition approved in 2007 as G11702(2007).DOI:10.1520/G0117-13.2For 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 5.3 The sequence of steps in assembling and handling thedata is as follows(refer to the designated columns in Fig.1):5.3.1 Calculate the average value of the data for each of Nlaboratories.(Column D)5.3.2 Calculate the average value Q of all the laboratoryaverages.(Cell D13)5.3.3 Calculate the standard deviation values for eachlaboratory.Note that th