ASTM E2653-08

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Designation:E2653–08
Standard Practice for
Conducting an Interlaboratory Study to Determine the
Precision of a Fire Test Method with Fewer Than Six
Participating Laboratories
This standard is issued under the fixed designation E 2653; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.7 This practice includes design information suitable for
use with the development of interlaboratory studies for test
1.1 This practice describes the techniques for planning,
methods that have categorization (go-no-go) allocation test
conducting,analyzing,andtreatingresultsofaninterlaboratory
results.However,itdoesnotprovidearecommendedstatistical
study (ILS) for estimating the precision of a fire test method
practice for evaluating the go-no-go data.
when fewer than six laboratories are available to meet the
1.8 This standard does not purport to address all of the
recommended minimum requirements of Practice E 691. Data
safety concerns, if any, associated with its use. It is the
obtainedfromaninterlaboratorystudyareusefulinidentifying
responsibility of the user of this standard to establish appro-
variables that require modifications for improving test method
priate safety and health practices and determine the applica-
performance and precision.
bility of regulatory limitations prior to use.
1.2 Precision estimates developed using this practice will
not be statistically equivalent to precision estimates produced
2. Referenced Documents
by Practice E 691 because a small number of laboratories are
2.1 ASTM Standards:
used. The smaller number of participating laboratories will
E 176 Terminology of Fire Standards
seriously reduce the value of precision estimates reported by
E 177 Practice for Use of the Terms Precision and Bias in
this practice. However, under circumstances where only a
ASTM Test Methods
limited number of laboratories are available to participate in an
E 178 Practice for Dealing With Outlying Observations
ILS, precision estimates developed by this practice will pro-
E 456 Terminology Relating to Quality and Statistics
vide the user with useful information concerning precision for
E 691 Practice for Conducting an Interlaboratory Study to
a test method.
Determine the Precision of a Test Method
1.3 A minimum of three qualified laboratories is required
E 1169 Practice for Conducting Ruggedness Tests
for conducting an ILS using this practice. If six or more
E 2335 Guide for Laboratory Monitors
laboratories are available to participate in an ILS for a given
fire test method, Practice E 691 shall be used for conducting
3. Terminology
the ILS.
3.1 Definitions—For formal definitions of statistical terms,
1.4 Since the primary purpose of this practice is the devel-
seeTerminologyE 456.Forformaldefinitionsoffireterms,see
opmentoftheinformationneededforaprecisionstatement,the
Terminology E 176.
experimental design in this practice will not be optimum for
3.2 Definitions of Terms Specific to This Standard:
evaluatingallmaterials,testmethods,orasatoolforindividual
3.2.1 test method and protocol—in this practice, the term
laboratory analysis.
“test method” is used both for the actual measurement process
1.5 Because of the reduced number of participating labora-
and for the written description of the process, while the term
tories a Laboratory Monitor shall be used in the ILS. See
“protocol” is used for the directions given to the laboratories
Standard Guide E 2335.
for conducting the ILS.
1.6 Field of Application—This practice is concerned with
3.2.2 repeatability and reproducibility—these terms deal
test methods that yield numerical values or a series of
with the variability of test results obtained under specified
numerical values for different fire-test response properties.The
laboratory conditions. Repeatability concerns the variability
numerical values mentioned above are typically the result of
between independent test results obtained within a single
calculations from a set of measurements.
1 2
This practice is under the jurisdiction of ASTM Committee E05 on Fire For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Standards and is the direct responsibility of Subcommittee E05.15 on Furnishings contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
and Contents. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Oct. 1, 2008. Published November 2008. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2653–08
laboratory in the shortest practical period of time by a single followed to determine test method precision. Precision results
operator with a specific set of test apparatus using test produced by the procedures presented in this standard will not
specimens(ortestunits)takenatrandomfromasinglequantity have the same degree of accuracy as results generated by a full
of homogeneous material obtained or prepared for the ILS. E 691 protocol. This procedure will allow for the development
Reproducibility deals with the variability between single test of useful precision results when a full compliment of labora-
results obtained in different laboratories, each of which has tories is not available for interlaboratory testing.
applied the test method to test specimens (or test units) taken 5.2 This practice is based on recommendations for inter-
at random from a single quantity of homogeneous material laboratory studies and data analysis presented in Practice
obtained or prepared for the ILS. E 691. This practice does not concern itself with the develop-
3.3 For further discussion of the terms discussed above, see ment of test methods but with a standard means for gathering
Practice E 177 and the formal definitions in Terminology information and treating the data needed for developing a
E 456. precision statement for a fire test method when a complete
E 691 interlaboratory study and data analysis are not possible.
4. Summary of Practice
PLANNING THE ILS
4.1 The procedure presented in this practice consists of
three basic steps: planning the interlaboratory study, guiding
6. Planning
thetestingphaseofthestudy,andanalyzingthetestresultdata.
6.1 Task Group—Either the task group that developed the
The analysis evaluates the consistency of the data through the
test method or a special task group appointed for the purpose
use of numerical estimates of precision of the test method
must have overall responsibility for the ILS, including funding
pertaining to both within-laboratory repeatability and between-
whereappropriate,staffing,thedesignoftheILS,anddecision-
laboratory reproducibility.
making with regard to questionable data. The task group shall
4.2 Planning of the interlaboratory study will include a
decideonthenumberoflaboratories,materials,andtestresults
review of the test procedure to be used in the interlaboratory
for each material. In addition, it shall specify any special
study.This review will identify portions of the test method that
calibration procedures and the repeatability conditions to be
appear to contribute to a loss in precision. Special interlabora-
specified in the protocol.
tory instructions or modifications to the test method wording
6.2 ILS Coordinator—The task group must appoint one
are made as needed to clarify these sections and often result in
individual to act as overall coordinator for conducting the ILS.
a modification to the test method following the interlaboratory
Thecoordinatorwillsupervisethedistributionofmaterialsand
study.
protocols to the laboratories and receive the test result reports
4.3 A manager for the interlaboratory study and an inter-
from the laboratories. Scanning the reports for gross errors and
laboratory test monitor shall be selected. The same person is
checking with the laboratories, when such errors are found,
allowed to conduct both functions.
will also be the responsibility of the coordinator. The coordi-
4.4 Parties conducting an interlaboratory precision study of
nator will consult as needed with a statistician in questionable
a test method will acquire participation agreements with as
cases.
manylaboratoriesaspossiblethatarewillingtotakepartinthe
6.3 Laboratory Monitor—The task group must appoint one
interlaboratory study and have the capability to run the test
individual to act as a laboratory monitor for the ILS. The
method of interest. A minimum of three laboratories shall
laboratorymonitorwilldevelopanILSchecklistspecifictothe
participateintheprecisionstudy.Precisionresultswillincrease
test method, inspect the test laboratories for equipment con-
in quality with a larger number of participating laboratories.
formity and operator training, verify compatibility of the data
4.5 The types of materials and number of test specimens
acquisition system, and based on the Checklist and inspection
shall be selected for the interlaboratory study. No less than
results report to the sponsoring ASTM Subcommittee. Com-
three test specimens shall be selected for the interlaboratory
pletedetailsforthefunctionofalaboratorymonitorarelocated
study, and they shall be selected to reflect the range of
in Guide E 2335.
performance of test specimens normally evaluated by the test
6.4 Statistician—The task group shall obtain the assistance
method.Aminimum of three replicates shall be tested for each
of a person skilled in the use of statistical procedures, the test
test material selected. If a standard reference material is
method being studied, and with the materials being tested in
available for the test method, the material shall be included as
order to ensure that the requirements in this practice are met in
a specimen in the interlaboratory study. If a standard reference
an efficient and effective manner. This person will conduct the
material is not available, a test specimen that consistently
data analysis using procedures given in this standard and will
produces low variability test results shall be selected as a
assist the task group in interpreting results from the data
reference material for the interlaboratory study.
analysis.
5. Significance and Use
7. Basic Design
5.1 ASTM regulations require precision statements in all
test methods in terms of repeatability and reproducibility. This 7.1 Keep the ILS design simple in order to obtain estimates
practice is used when the number of participating laboratories of within-and between-laboratory variability that are free of
or materials being tested, or both, in a precision study is less secondary effects. The basic design is represented by a two-
than the number specified by Practice E 691. When possible, it way classification table in which the rows represent the
is strongly recommended that a full E 691 standard protocol be laboratories, the columns represent the materials, and the cell
E2653–08
(the intersection of a row and column) contains the test results 9.2 The pilot run results give the task group an indication of
made by a particular laboratory on a particular material (see how well each laboratory will perform in terms of promptness
Table 1).
and following the protocol. Laboratories with poor perfor-
7.2 An ILS using this practice shall include enough labora-
mance are encouraged and helped to take corrective action.
tories to represent a reasonable cross-section of the population
9.3 All steps of the procedures described in this practice
of qualified laboratories. A minimum of three laboratories is
shall be followed in detail to ensure that these directions are
necessary for carrying out an ILS using this practice.
understood, to disclose any weakness in the protocol or test
method.
8. Test Method
8.1 Of prime importance is the existence of a valid, well-
10. Full Scale Run
written test method that has been developed in one or more
10.1 Materials Preparation and Distribution:
competentlaboratories,andhadbeensubjectedtoaruggedness
test prior to the ILS. 10.1.1 Sample Preparation and Labeling—Prepare enough
8.2 The ruggedness test is a screening procedure for inves-
of each material to supply at least 50 % more than needed by
tigating the effects of variations in environmental and other
the number of laboratories committed to the ILS. Label each
conditions in order to determine how control of such test
test unit or specimen with a letter for the material and a
conditions shall be specified in the written description of the
sequential number. Thus, for three laboratories and three
method. Details for ruggedness testing are found in Guide
results for each laboratory the test units for materials B would
E 1169.
be numbered from B1 to B14.
8.3 Awritten version of the test method must be developed
10.1.2 Randomization—For each material independently,
for the ILS (but not necessarily published as a standard
allocate the specified number of test units or test specimens to
method). This draft shall describe the test apparatus and
each laboratory, using a random number table, or a suitable
procedure in terms that are easily understood and followed in
computerized random number based program.
any properly equipped laboratory by competent personnel with
10.1.3 Shipping—Ensure that the test specimens are pack-
knowledge of the materials and the property to be tested. The
aged properly to arrive in the desired condition. Clearly
method shall contain safety and calibration procedures, details
indicate the name of the person who has been designated as
on control related limits that potentially cause test result
ILS supervisor at the laboratory on the address of each
variability, and specify how test results are to be reported.
package. Follow shipping directions provided by each labora-
ILS TESTING tory to ensure prompt delivery of the package.
10.1.4 Follow-up—Once the test specimens have been
9. Pilot Run
shipped, the ILS coordinator shall call each laboratory ILS
9.1 Prior to beginning testing for the formal ILS a prelimi- supervisor to confirm that all test specimens have arrived
nary laboratory evaluation study shall be carried out using a
safely. If the task group has decided to intermingle test
well characterized test material of known performance. This
specimens from different materials in the order of testing, the
preliminary study is managed by the ILS Coordinator and
testing shall not start until all the test specimens have arrived
Laboratory Monitor and is used to determine if each of the
at the laboratory so they will be tested in the specified ord
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