1、Designation: E2653 14 An American National StandardStandard Practice forConducting an Interlaboratory Study to Determine PrecisionEstimates for a Fire Test Method with Fewer Than SixParticipating Laboratories1This standard is issued under the fixed designation E2653; the number immediately following
2、 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 describ
3、es the techniques for planning,conducting, analyzing, and treating results of an interlaboratorystudy (ILS) for estimating the precision of a fire test methodwhen fewer than six laboratories are available to meet therecommended minimum requirements of Practice E691. Dataobtained from an interlaborat
4、ory study are useful in identifyingvariables that require modifications for improving test methodperformance and precision.1.2 Precision estimates developed using this practice willnot be statistically equivalent to precision estimates producedby Practice E691 because a small number of laboratories
5、areused. The smaller number of participating laboratories willseriously reduce the value of precision estimates reported bythis practice. However, under circumstances where only alimited number of laboratories are available to participate in anILS, precision estimates developed by this practice will
6、 pro-vide the user with useful information concerning precision fora test method.1.3 A minimum of three qualified laboratories is requiredfor conducting an ILS using this practice. If six or morelaboratories are available to participate in an ILS for a givenfire test method, Practice E691 shall be u
7、sed for conducting theILS.1.4 Since the primary purpose of this practice is the devel-opment of the information needed for a precision statement, theexperimental design in this practice will not be optimum forevaluating all materials, test methods, or as a tool for individuallaboratory analysis.1.5
8、Because of the reduced number of participating labora-tories a Laboratory Monitor shall be used in the ILS. SeeStandard Guide E2335.1.6 Field of ApplicationThis practice is concerned withtest methods that yield numerical values or a series ofnumerical values for different fire-test response properti
9、es. Thenumerical values mentioned above are typically the result ofcalculations from a set of measurements.1.7 This practice includes design information suitable foruse with the development of interlaboratory studies for testmethods that have categorization (go-no-go) allocation testresults. However
10、, it does not provide a recommended statisticalpractice for evaluating the go-no-go data.1.8 This fire standard cannot be used to provide quantitativemeasures.1.9 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user
11、 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:2E176 Terminology of Fire StandardsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE178 P
12、ractice for Dealing With Outlying ObservationsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1169 Practice for Conducting Ruggedness TestsE2335 Guide for Laboratory Monitors3. Terminology3.1 Definiti
13、onsFor formal definitions of statistical terms,see Terminology E456. For formal definitions of fire terms, seeTerminology E176.3.2 Definitions of Terms Specific to This Standard:1This practice is under the jurisdiction of ASTM Committee E05 on FireStandards and is the direct responsibility of Subcom
14、mittee E05.31 on Terminologyand Services / Functions.Current edition approved Dec. 1, 2014. Published December 2014. Originallyapproved in 2008. Last previous edition approved in 2009 as E2653-09. DOI:10.1520/E2653-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AS
15、TM 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 States13.2.1 protocol, nin this prac
16、tice, directions given to thelaboratories for conducting the interlaboratory study (ILS).3.2.2 repeatability (of results and measurements),nquantitative expression of the random error associated withsuccessive measurements of the same measurand carried outsubject to all of the following conditions:
17、the same measure-ment procedure, the same observer, the same measuringinstrument, used under the same conditions, the same location,and repetition over a short period of time.3.2.2.1 DiscussionRepeatability deals with results in asingle laboratory while reproducibility deals with results ob-tained i
18、n different laboratories.3.2.3 reproducibility (of results of measurements),nquantitative expression of the random error associated withsuccessive measurements of the same measurand carried out byoperators working in different laboratories, each obtainingsingle results on identical test material whe
19、n applying the samemethod.3.2.3.1 DiscussionRepeatability deals with results in asingle laboratory while reproducibility deals with results ob-tained in different laboratories.3.2.4 test method, nin this practice, description of theactual measurement process as well as written description ofthe proc
20、ess.3.3 For further discussion of the terms discussed above, seePractice E177 and the formal definitions in Terminology E456.4. Summary of Practice4.1 The procedure presented in this practice consists ofthree basic steps: planning the interlaboratory study, guidingthe testing phase of the study, and
21、 analyzing the test result data.The analysis evaluates the consistency of the data through theuse of numerical estimates of precision of the test methodpertaining to both within-laboratory repeatability and between-laboratory reproducibility.4.2 Planning of the interlaboratory study will include are
22、view of the test procedure to be used in the interlaboratorystudy. This review will identify portions of the test method thatappear to contribute to a loss in precision. Special interlabora-tory instructions or modifications to the test method wordingare made as needed to clarify these sections and
23、often result ina modification to the test method following the interlaboratorystudy.4.3 A manager for the interlaboratory study and an inter-laboratory test monitor shall be selected. The same person isallowed to conduct both functions.4.4 Parties conducting an interlaboratory precision study ofa te
24、st method will acquire participation agreements with asmany laboratories as possible that are willing to take part in theinterlaboratory study and have the capability to run the testmethod of interest. A minimum of three laboratories shallparticipate in the precision study. Precision results will in
25、creasein quality with a larger number of participating laboratories.4.5 The types of materials and number of test specimensshall be selected for the interlaboratory study. No less thanthree test specimens shall be selected for the interlaboratorystudy, and they shall be selected to reflect the range
26、 ofperformance of test specimens normally evaluated by the testmethod.Aminimum of three replicates shall be tested for eachtest material selected. If a standard reference material isavailable for the test method, the material shall be included asa specimen in the interlaboratory study. If a standard
27、 referencematerial is not available, a test specimen that consistentlyproduces low variability test results shall be selected as areference material for the interlaboratory study.5. Significance and Use5.1 ASTM regulations require precision statements in alltest methods in terms of repeatability and
28、 reproducibility. Thispractice is used when the number of participating laboratoriesor materials being tested, or both, in a precision study is lessthan the number specified by Practice E691. When possible, itis strongly recommended that a full E691 standard protocol befollowed to determine test met
29、hod precision. Precision resultsproduced by the procedures presented in this standard will nothave the same degree of accuracy as results generated by a fullE691 protocol. This procedure will allow for the developmentof useful precision results when a full compliment of labora-tories is not availabl
30、e for interlaboratory testing.5.2 This practice is based on recommendations for inter-laboratory studies and data analysis presented in Practice E691.This practice does not concern itself with the development oftest methods but with a standard means for gathering informa-tion and treating the data n
31、eeded for developing a precisionstatement for a fire test method when a complete E691interlaboratory study and data analysis are not possible.PLANNING THE ILS6. Planning6.1 Task GroupEither the task group that developed thetest method or a special task group appointed for the purposemust have overal
32、l responsibility for the ILS, including fundingwhere appropriate, staffing, the design of the ILS, and decision-making with regard to questionable data. The task group shalldecide on the number of laboratories, materials, and test resultsfor each material. In addition, it shall specify any specialca
33、libration procedures and the repeatability conditions to bespecified in the protocol.6.2 ILS CoordinatorThe task group must appoint oneindividual to act as overall coordinator for conducting the ILS.The coordinator will supervise the distribution of materials andprotocols to the laboratories and rec
34、eive the test result reportsfrom the laboratories. Scanning the reports for gross errors andchecking with the laboratories, when such errors are found,will also be the responsibility of the coordinator. The coordi-nator will consult as needed with a statistician in questionablecases.6.3 Laboratory M
35、onitorThe task group must appoint oneindividual to act as a laboratory monitor for the ILS. Thelaboratory monitor will develop an ILS checklist specific to thetest method, inspect the test laboratories for equipment con-formity and operator training, verify compatibility of the dataacquisition syste
36、m, and based on the Checklist and inspectionE2653 142results report to the sponsoring ASTM Subcommittee. Com-plete details for the function of a laboratory monitor are locatedin Guide E2335.6.4 StatisticianThe task group shall obtain the assistanceof a person skilled in the use of statistical proced
37、ures, the testmethod being studied, and with the materials being tested inorder to ensure that the requirements in this practice are met inan efficient and effective manner. This person will conduct thedata analysis using procedures given in this standard and willassist the task group in interpretin
38、g results from the dataanalysis.7. Basic Design7.1 Keep the ILS design simple in order to obtain estimatesof within-and between-laboratory variability that are free ofsecondary effects. The basic design is represented by a two-way classification table in which the rows represent thelaboratories, the
39、 columns represent the materials, and the cell(the intersection of a row and column) contains the test resultsmade by a particular laboratory on a particular material (seeTable 1).7.2 An ILS using this practice shall include enough labora-tories to represent a reasonable cross-section of the populat
40、ionof qualified laboratories. A minimum of three laboratories isnecessary for carrying out an ILS using this practice.8. Test Method8.1 Of prime importance is the existence of a valid, well-written test method that has been developed in one or morecompetent laboratories, and had been subjected to a
41、ruggednesstest prior to the ILS.8.2 The ruggedness test is a screening procedure for inves-tigating the effects of variations in environmental and otherconditions in order to determine how control of such testconditions shall be specified in the written description of themethod. Details for ruggedne
42、ss testing are found in GuideE1169.8.3 A written version of the test method must be developedfor the ILS (but not necessarily published as a standardmethod). This draft shall describe the test apparatus andprocedure in terms that are easily understood and followed inany properly equipped laboratory
43、by competent personnel withknowledge of the materials and the property to be tested. Themethod shall contain safety and calibration procedures, detailson control related limits that potentially cause test resultvariability, and specify how test results are to be reported.ILS TESTING9. Pilot Run9.1 P
44、rior to beginning testing for the formal ILS a prelimi-nary laboratory evaluation study shall be carried out using awell characterized test material of known performance. Thispreliminary study is managed by the ILS Coordinator andLaboratory Monitor and is used to determine if each of theparticipatin
45、g laboratories are capable of conducting tests asspecified by the written ILS test method. These preliminarytests conducted in the participating laboratories are typicallyobserved by the Laboratory Monitor as a part of the laboratoryqualification process.9.2 The pilot run results give the task group
46、 an indication ofhow well each laboratory will perform in terms of promptnessand following the protocol. Laboratories with poor perfor-mance are encouraged and helped to take corrective action.9.3 All steps of the procedures described in this practiceshall be followed in detail to ensure that these
47、directions areunderstood, to disclose any weakness in the protocol or testmethod.10. Full Scale Run10.1 Materials Preparation and Distribution:10.1.1 Sample Preparation and LabelingPrepare enoughof each material to supply at least 50 % more than needed bythe number of laboratories committed to the I
48、LS. Label eachtest unit or specimen with a letter for the material and asequential number. Thus, for three laboratories and threeresults for each laboratory the test units for materials B wouldbe numbered from B1 to B14.10.1.2 RandomizationFor each material independently,allocate the specified numbe
49、r of test units or test specimens toeach laboratory, using a random number table, or a suitablecomputerized random number based program.10.1.3 ShippingEnsure that the test specimens are pack-aged properly to arrive in the desired condition. Clearlyindicate the name of the person who has been designated asILS supervisor at the laboratory on the address of eachpackage. Follow shipping directions provided by each labora-tory to ensure prompt delivery of the package.10.1.4 Follow-upOnce the test specimens have beenshipped, the ILS coordinator shall call each laboratory ILS
