ASTM E2480-12(2022)
(Practice)Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method with Multi-Valued Measurands
Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method with Multi-Valued Measurands
SIGNIFICANCE AND USE
5.1 ASTM regulations require precision statements for all test methods in terms of repeatability and reproducibility. This practice may be used in obtaining the information needed to prepare a precision statement in accordance with Practice E177 and the “Blue Book.”
SCOPE
1.1 This practice describes the techniques for planning, conducting, and analyzing the results of an interlaboratory study (ILS) conducted for certain test methods within Committee E12.
1.2 This practice does not concern itself with the development of the test method but rather with the gathering of the information needed for the precision and bias statement after the completion of development of the test method. The data obtained in the ILS may indicate, however, that further effort is needed to improve the test method.
1.3 This practice is concerned exclusively with test methods that derive a multi-valued measurand, such as, but not limited to, spectral reflectance, transmittance function, tristimulus values, or RGB values. Variation in measurements of such multi-valued measurands are usually analyzed by reducing the data to a single-valued parameter, such as color difference, ΔE.
1.4 This practice covers methods of dealing with the non-normal distribution of the variation of sets of color-differences. This is done so that the user may derive valid statistics from such non-normal distributions.
1.5 This practice does not cover test methods, even in Committee E12, whose measurands are single-valued, or whose variations are known to be normally distributed. Task groups involved with such test methods are referred to Practice E691 which contains preferable methods of analyzing data with those properties.
1.6 This practice is not intended to establish a method for estimating possible color-difference tolerances.
1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2480 − 12 (Reapproved 2022)
Standard Practice for
Conducting an Interlaboratory Study to Determine the
Precision of a Test Method with Multi-Valued Measurands
This standard is issued under the fixed designation E2480; 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 responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 This practice describes the techniques for planning,
mine the applicability of regulatory limitations prior to use.
conducting, and analyzing the results of an interlaboratory
1.9 This international standard was developed in accor-
study (ILS) conducted for certain test methods within Com-
dance with internationally recognized principles on standard-
mittee E12.
ization established in the Decision on Principles for the
1.2 This practice does not concern itself with the develop-
Development of International Standards, Guides and Recom-
ment of the test method but rather with the gathering of the
mendations issued by the World Trade Organization Technical
information needed for the precision and bias statement after
Barriers to Trade (TBT) Committee.
the completion of development of the test method. The data
obtained in the ILS may indicate, however, that further effort is
2. Referenced Documents
needed to improve the test method.
2.1 ASTM Standards:
1.3 Thispracticeisconcernedexclusivelywithtestmethods
E177 Practice for Use of the Terms Precision and Bias in
that derive a multi-valued measurand, such as, but not limited
ASTM Test Methods
to, spectral reflectance, transmittance function, tristimulus
E284 Terminology of Appearance
values, or RGB values. Variation in measurements of such
E691 Practice for Conducting an Interlaboratory Study to
multi-valued measurands are usually analyzed by reducing the
Determine the Precision of a Test Method
data to a single-valued parameter, such as color difference,∆E.
E1345 Practice for Reducing the Effect of Variability of
Color Measurement by Use of Multiple Measurements
1.4 This practice covers methods of dealing with the non-
normal distribution of the variation of sets of color-differences.
3. Terminology
This is done so that the user may derive valid statistics from
such non-normal distributions.
3.1 Definitions—For color and appearance terms, see Ter-
minology E284.
1.5 This practice does not cover test methods, even in
3.2 Definitions of Terms Specific to This Standard:
Committee E12, whose measurands are single-valued, or
3.2.1 precision and bias, n—when a test method is applied
whose variations are known to be normally distributed. Task
to a large number of specimens that are as nearly alike as
groups involved with such test methods are referred to Practice
possible, the test results obtained nevertheless will not all have
E691 which contains preferable methods of analyzing data
the same values.Ameasure of the degree of agreement among
with those properties.
these test results describes the precision of the test method for
1.6 This practice is not intended to establish a method for
that material. This practice is designed only to estimate the
estimating possible color-difference tolerances.
precision of a test method. However, when accepted reference
1.7 The values stated in SI units are to be regarded as the values are known for the materials being tested, the test result
standard. The values given in parentheses are for information data obtained in accordance with this practice may be used to
only. estimate the bias of the test method. For a discussion of bias
estimation, see Practice E177.
1.8 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.2.2 repeatability and reproducibility, n—the term repeat-
abilityconcernsthevariabilitybetweenindependenttestresults
This practice is under the jurisdiction of ASTM Committee E12 on Color and
Appearance and is the direct responsibility of Subcommittee E12.02 on Spectro-
photometry and Colorimetry. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
CurrenteditionapprovedJune1,2022.PublishedJuly2022.Originallyapproved contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
in 2007. Last previous edition approved in 2017 as E2480 – 12 (2017). DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E2480-12R22. theASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2480 − 12 (2022)
obtained within a single laboratory in the shortest practical PLANNING THE INTERLABORATORY STUDY (ILS)
period of time by a single operator applying the test method
6. ILS Membership
with a specific set of test apparatus using test specimens taken
at random from a single quantity of homogeneous material
6.1 Task Group—Either the task group that developed the
obtained, or prepared, for the ILS. The term reproducibility
test method or a special task group formed specifically for the
concerns the variability between single test results obtained in
purpose must have overall responsibility for the funding,
different laboratories, each by a different operator, each of
staffing, design, and decision-making with regard to data in the
whom has applied the test method to specimens taken at
ILS. The task group should decide on the number of
random from a single quantity of homogeneous material
laboratories, materials, and test results for the ILS. The task
obtained, or prepared, for the ILS.
group should obtain a statement of willingness to participate
3.2.2.1 Discussion—The above single operator and single
fromeachoftheparticipatinglaboratories.Inaddition,thetask
apparatus requirement, as specified in 3.2.2, means that for a
group should obtain, randomize, and distribute the specimens
particular step in the measurement process the same combina-
to be tested.
tionofoperatorandapparatusisusedtoobtaineverytestresult
6.2 ILS Coordinator—The task group must appoint one
on every specimen. Thus, one operator could prepare and
individual to act as overall coordinator of the ILS. This person
mount the specimen, another actuate the measurements, and
hasresponsibilityfordistributingthematerialsandprotocolsto
still another record the value of the result.
the laboratories, and for receiving the test result reports from
3.2.2.2 Discussion—The shortest practical period of time
the laboratories.
means that the test results are obtained in a time not less than
6.3 Statistician:
normal testing and not so long as to permit significant changes
6.3.1 The test method task group should obtain the assis-
in material, equipment, calibration, or environment.
tance of a person familiar with the statistical procedures of this
3.2.2.3 Discussion—Therequirementthatthemeasurements
practice and with the materials being tested. When no such
be independent means that a single test determination begins
person is available, the task group should obtain the assistance
with the mounting of the specimen on the sample port or in the
of a statistician who has experience in practical work with data
transmission compartment, and ends with the removal of the
from materials. Task group members need not be members of
test specimen from the port or compartment.All measurements
ASTM.
are made with replacement.
6.3.2 The calculation of the statistics for each material may
3.2.2.4 Discussion—The requirement for different laborato-
be readily done by persons not having knowledge of statistics,
ries does not exclude the case where more than one instrument
but having basic knowledge of calculating and computers.
resides in the same company, laboratory, or room, provided
that each has an independent and separate calibration traceabil-
6.4 Laboratory ILS Supervisor—Each participating labora-
ity path from each other.
tory must have an ILS supervisor to oversee the conduct of the
ILS within the laboratory and to communicate with the ILS
3.2.3 test method and protocol, n—in this practice, the term
Coordinator. This supervisor’s name should be obtained at the
testmethodappliestoboththeactualmeasurementprocessand
the written description of the process, while the term protocol time that the laboratory states its willingness to participate.
refers to the written instructions given the participants for
7. Basic Design
conducting the ILS.
7.1 Keep the design as simple as possible in order to obtain
3.2.4 test specimens, n—the portion of the material being
estimates of within- and between-laboratory variability that are
tested needed for obtaining a single test determination is called
free of secondary effects. The basic design is represented by a
a test specimen.Asingle test specimen may be measured more
two-way classification table, in which the rows represent the
than once and the results combined to produce a test result if
laboratories, and the columns represent the materials, and each
the protocol or test method so specifies.
cell (the intersection of a row and a column) contains a test
4. Summary of Practice result made by a particular laboratory on a particular material.
4.1 The procedure presented in this practice consists of
8. Test Method
three steps: planning the interlaboratory study, guiding the
8.1 A written version of the test method (but not one
testing phase of the study, and analyzing the test result data.
necessarily as yet published as an ASTM standard) must have
The analysis includes the calculation of the numerical mea-
been developed and be distributed with the protocol if other-
sures of precision of the test method applying to both within-
wise unavailable to the participating laboratories.
laboratory repeatability and between-laboratory reproducibil-
ity.
8.2 The test method should have been subjected to a
screening procedure, in order that some experience with the
5. Significance and Use
test method has been obtained before an ILS is conducted.Test
5.1 ASTM regulations require precision statements for all conditionsthataffectthetestresults,ifany,shouldbeidentified
test methods in terms of repeatability and reproducibility. This and a statement of the needed degree of control of these
practice may be used in obtaining the information needed to conditions should be provided. In addition, the test method, or
prepareaprecisionstatementinaccordancewithPracticeE177 the protocol, should specify to how many digits of precision
and the “Blue Book.” each test result is to be measured.
E2480 − 12 (2022)
8.3 The test method should specify the calibration proce- 11. Number of Test Results per Material
dure and the frequency of calibration.
11.1 The minimum number of test results per laboratory on
each material shall be four.The number may rise to as many as
9. Laboratories
ten when test results are apt to vary considerably. The number
9.1 Number of Laboratories—An ILS should be run with no
of test results in any one ILS will be determined by the Task
fewer than 8 laboratories. It is recommended that the number
Group, based upon the desired level of tolerance and the
of laboratories be set at 10, and it is desirable that more
anticipated variation of test results from the test method.
laboratories be included if available in order that the ILS is
conducted with a reasonable cross-section of competent labo-
12. Protocol
ratories. Under no circumstances, allowing for attrition, should
12.1 Prepare a written protocol containing instructions for
the final statement of precision of a test method be based on
the participating laboratories to follow. Clearly identify the
fewer than 6 laboratories when the requisite three materials are
specific version of the test method being studied. If the test
employed.
method allows options in apparatus or procedure, clearly
9.1.1 Under some circumstances and with some test
specify which option has been selected for conducting the ILS.
methods, it may be impossible to obtain the necessary six
laboratories. Under these conditions, it is permissible to 12.2 Cite the name, address, telephone number, and E-mail
proceed with the supplementation of additional materials to addressoftheILSCoordinator.Urgetheparticipantstocallthe
make up for the loss of degrees of freedom using the following coordinator with any questions that may arise as to the conduct
schedule of materials and laboratories:
of the ILS.
Required Minimum
12.3 Request that the participating laboratory keep a record
Number of Labs
Number of Materials
(or log) of any special events that arise during any phase of the
testing. This record should include any specific aspects of the
apparatus, calibration, or procedure that ought to be commu-
9.2 The ILS should not be restricted to a group of labora- nicated to the task group to allow them to prepare the final
toriesjudgedtobeexceptionallyqualifiedandequippedforthe research report on the ILS.
ILS. Precision estimates for a test method should be obtained
12.4 Supply data sheets for each material for recording the
through conditions where laboratories are competent and
raw data as observations are made, or if it would be more
personnelareoperatingunderconditionsthatwillprevailwhen
convenient for the participating laboratory, specify the format,
the test method is used in practice.
includingthenumberofsignificantdigitstoberecorded,ofthe
data to be returned to the coordinator.
10. Materials
10.1 The term material means anything with a property that CONDUCTING THE TESTING PHASE OF THE ILS
can be measured. Different materials having the same property
may be expected to have different levels of the property,
13. Full Scale Run
meaning higher or lower levels of the property.
13.1 Material Preparation and Distribution:
10.2 The ILS should include a minimum of three different
13.1.1 Sample Preparation and Labeling—Prepare enough
materials each with a different levels of the property under test, material to supply 50 % more than needed by the number of
and to be broadly applicable more than three materials of
laboratories committed to the ILS. Label each test specimen
differing levels should be assessed. with the laboratory number and a letter designator referring to
the material. Thus, if 8 laboratories were participating in a test
10.3 The materials involved in any one ILS should di
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