1、Designation: E 2653 09Standard 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 E 2653; the number immediately following the designation indicates t
2、he 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 planni
3、ng,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 E 691. Dataobtained from an interlaboratory study are useful in ide
4、ntifyingvariables 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 E 691 because a small number of laboratories areused. The smaller numbe
5、r 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 pro-vide the user with us
6、eful 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 E 691 shall be used for conductingthe ILS
7、.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 Because of the reduced nu
8、mber of participating labora-tories a Laboratory Monitor shall be used in the ILS. SeeStandard Guide E 2335.1.6 Field of ApplicationThis practice is concerned withtest methods that yield numerical values or a series ofnumerical values for different fire-test response properties. Thenumerical values
9、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, it does not provide a
10、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 of this standard to est
11、ablish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 176 Terminology of Fire StandardsE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 178 Practice for Dealing W
12、ith Outlying ObservationsE 456 Terminology Relating to Quality and StatisticsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1169 Practice for Conducting Ruggedness TestsE 2335 Guide for Laboratory Monitors3. Terminology3.1 DefinitionsFor formal def
13、initions of statistical terms,see Terminology E 456. For formal definitions of fire terms, seeTerminology E 176.3.2 Definitions of Terms Specific to This Standard:3.2.1 test method and protocolin this practice, the term“test method” is used both for the actual measurement process1This practice is un
14、der the jurisdiction of ASTM Committee E05 on FireStandards and is the direct responsibility of Subcommittee E05.15 on Furnishingsand Contents.Current edition approved April 1, 2009. Published May 2009. Originallyapproved in 2008. Last previous edition approved in 2008 as E 2653-08.2For referenced A
15、STM 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consho
16、hocken, PA 19428-2959, United States.and for the written description of the process, while the term“protocol” is used for the directions given to the laboratoriesfor conducting the ILS.3.2.2 repeatability and reproducibilitythese terms dealwith the variability of test results obtained under specifie
17、dlaboratory conditions. Repeatability concerns the variabilitybetween independent test results obtained within a singlelaboratory in the shortest practical period of time by a singleoperator with a specific set of test apparatus using testspecimens (or test units) taken at random from a single quant
18、ityof homogeneous material obtained or prepared for the ILS.Reproducibility deals with the variability between single testresults obtained in different laboratories, each of which hasapplied the test method to test specimens (or test units) takenat random from a single quantity of homogeneous materi
19、alobtained or prepared for the ILS.3.3 For further discussion of the terms discussed above, seePractice E 177 and the formal definitions in TerminologyE 456.4. Summary of Practice4.1 The procedure presented in this practice consists ofthree basic steps: planning the interlaboratory study, guidingthe
20、 testing phase of the study, and 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 interl
21、aboratory study will include areview 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 neede
22、d to clarify these sections and 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 interl
23、aboratory precision study ofa test 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
24、study. Precision results will increasein 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
25、be selected to reflect the range ofperformance of test specimens normally evaluated by the testmethod. A minimum 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 in
26、terlaboratory study. If a standard 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 met
27、hods in terms of repeatability and 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 E 691. When possible, itis strongly recommended that a full E 691 standard proto
28、col befollowed to determine test method precision. Precision resultsproduced by the procedures presented in this standard will nothave the same degree of accuracy as results generated by a fullE 691 protocol. This procedure will allow for the developmentof useful precision results when a full compli
29、ment of labora-tories is not available for interlaboratory testing.5.2 This practice is based on recommendations for inter-laboratory studies and data analysis presented in PracticeE 691. This practice does not concern itself with the develop-ment of test methods but with a standard means for gather
30、inginformation and treating the data needed for developing aprecision statement for a fire test method when a completeE 691 interlaboratory 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 ap
31、pointed for the purposemust have overall 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 a
32、ddition, it shall specify any specialcalibration 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 a
33、ndprotocols to the laboratories and receive 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 statisticia
34、n in questionablecases.6.3 Laboratory MonitorThe 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 com
35、patibility of the dataacquisition system, and based on the Checklist and inspectionresults report to the sponsoring ASTM Subcommittee. Com-plete details for the function of a laboratory monitor are locatedin Guide E 2335.6.4 StatisticianThe task group shall obtain the assistanceof a person skilled i
36、n the use of statistical procedures, 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 willassis
37、t the task group in interpreting results from the dataanalysis.E26530927. 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
38、the rows represent thelaboratories, the 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
39、reasonable cross-section of the populationof 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 lab
40、oratories, and had been subjected to a 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 descrip
41、tion of themethod. Details for ruggedness testing are found in GuideE 1169.8.3 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 foll
42、owed inany properly equipped laboratory 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
43、be reported.ILS TESTING9. Pilot Run9.1 Prior 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
44、 to determine if each of theparticipating 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 T
45、he pilot run results give the task group 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
46、followed in detail to ensure that these 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 n
47、umber of laboratories committed to the ILS. 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 in
48、dependently,allocate the specified number 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
49、 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 ILSsupervisor to confirm that all test specimens have arrivedsafely. If the task group has decided to intermingle testspecimens from different materials in the order of testing, thetesting shall not start until all the test specimens have arrivedat the laboratory so t
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