1、Designation: E 2653 08Standard Practice forConducting an Interlaboratory Study to Determine thePrecision of 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 the year
2、 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,cond
3、ucting, 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 identifyin
4、gvariables 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 number of pa
5、rticipating 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 useful in
6、formation 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.1.4 Si
7、nce 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 number of
8、 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 mention
9、ed 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 recomme
10、nded statisticalpractice for evaluating the go-no-go data.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-bil
11、ity 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 With Outlying ObservationsE 456 Terminology Relating to Quality and Statistics
12、E 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 definitions of statistical terms,see Terminology E 456. For formal definitions o
13、f 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 processand for the written description of the process, while the term“protocol” is used for the directio
14、ns given to the laboratoriesfor conducting the ILS.3.2.2 repeatability and reproducibilitythese terms dealwith the variability of test results obtained under specifiedlaboratory conditions. Repeatability concerns the variabilitybetween independent test results obtained within a single1This practice
15、is under the jurisdiction of ASTM Committee E05 on FireStandards and is the direct responsibility of Subcommittee E05.15 on Furnishingsand Contents.Current edition approved Oct. 1, 2008. Published November 2008.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cust
16、omer 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 Conshohocken, PA 19428-2959, United States.laboratory in the shortest practica
17、l period of time by a singleoperator with a specific set of test apparatus using testspecimens (or test units) taken at random from a single quantityof homogeneous material obtained or prepared for the ILS.Reproducibility deals with the variability between single testresults obtained in different la
18、boratories, each of which hasapplied the test method to test specimens (or test units) takenat random from a single quantity of homogeneous materialobtained or prepared for the ILS.3.3 For further discussion of the terms discussed above, seePractice E 177 and the formal definitions in TerminologyE 4
19、56.4. 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 analyzing the test result data.The analysis evaluates the consistency of the data through theuse of numerical estimates o
20、f precision of the test methodpertaining to both within-laboratory repeatability and between-laboratory reproducibility.4.2 Planning of the interlaboratory study will include areview of the test procedure to be used in the interlaboratorystudy. This review will identify portions of the test method t
21、hatappear 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 often result ina modification to the test method following the interlaboratorystudy.4.3 A manager for the interlaboratory
22、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 test method will acquire participation agreements with asmany laboratories as possible that are willing to take part in thei
23、nterlaboratory study and have the capability to run the testmethod of interest. A minimum of three laboratories shallparticipate in the precision study. Precision results will increasein quality with a larger number of participating laboratories.4.5 The types of materials and number of test specimen
24、sshall 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 ofperformance of test specimens normally evaluated by the testmethod. A minimum of three replicates shall be tested for e
25、achtest 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 referencematerial is not available, a test specimen that consistentlyproduces low variability test results shall be sel
26、ected 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 reproducibility. Thispractice is used when the number of participating laboratoriesor materials being tested, or both,
27、in a precision study is lessthan the number specified by Practice E 691. When possible, itis strongly recommended that a full E 691 standard protocol befollowed to determine test method precision. Precision resultsproduced by the procedures presented in this standard will nothave the same degree of
28、accuracy as results generated by a fullE 691 protocol. This procedure will allow for the developmentof useful precision results when a full compliment of labora-tories is not available for interlaboratory testing.5.2 This practice is based on recommendations for inter-laboratory studies and data ana
29、lysis presented in PracticeE 691. This practice does not concern itself with the develop-ment of test methods but with a standard means for gatheringinformation and treating the data needed for developing aprecision statement for a fire test method when a completeE 691 interlaboratory study and data
30、 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 overall responsibility for the ILS, including fundingwhere appropriate, staffing, the design of the ILS, and decision-mak
31、ing 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 specialcalibration procedures and the repeatability conditions to bespecified in the protocol.6.2 ILS CoordinatorThe task gr
32、oup 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 receive the test result reportsfrom the laboratories. Scanning the reports for gross errors andchecking with the labor
33、atories, 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 MonitorThe task group must appoint oneindividual to act as a laboratory monitor for the ILS. Thelaboratory monitor w
34、ill develop an ILS checklist specific to thetest method, inspect the test laboratories for equipment con-formity and operator training, verify compatibility of the dataacquisition system, and based on the Checklist and inspectionresults report to the sponsoring ASTM Subcommittee. Com-plete details f
35、or the function of a laboratory monitor are locatedin Guide E 2335.6.4 StatisticianThe task group shall obtain the assistanceof a person skilled in the use of statistical procedures, the testmethod being studied, and with the materials being tested inorder to ensure that the requirements in this pra
36、ctice 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 interpreting results from the dataanalysis.7. Basic Design7.1 Keep the ILS design simple in order to obtain estimatesof within-and bet
37、ween-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 columns represent the materials, and the cellE2653082(the intersection of a row and column) contains the test resultsmade
38、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 populationof qualified laboratories. A minimum of three laboratories isnecessary for carrying out an ILS using this practi
39、ce.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 ruggednesstest prior to the ILS.8.2 The ruggedness test is a screening procedure for inves-tigating the effects of
40、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 ruggedness testing are found in GuideE 1169.8.3 A written version of the test method must be developedfor the ILS (but not
41、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 by competent personnel withknowledge of the materials and the property to be tested. Themethod shall contain safet
42、y 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 Prior to beginning testing for the formal ILS a prelimi-nary laboratory evaluation study shall be carried out using
43、 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 theparticipating laboratories are capable of conducting tests asspecified by the written ILS test method. These preliminarytests
44、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 an indication ofhow well each laboratory will perform in terms of promptnessand following the protocol. Laborator
45、ies 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 directions areunderstood, to disclose any weakness in the protocol or testmethod.10. Full Scale Run10.1 Materials
46、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 ILS. Label eachtest unit or specimen with a letter for the material and asequential number. Thus, for three laborat
47、ories 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 number of test units or test specimens toeach laboratory, using a random number table, or a suitablecomputerized random
48、 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
49、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 they will be tested in the specified order.10.1.5 Replacement Sets of Test SpecimensAs the ILSprogresses, it is possible that a laboratory will discover t
