ASTM C802-14(2022)
(Practice)Standard Practice for Conducting an Interlaboratory Test Program to Determine the Precision of Test Methods for Construction Materials
Standard Practice for Conducting an Interlaboratory Test Program to Determine the Precision of Test Methods for Construction Materials
SIGNIFICANCE AND USE
4.1 This practice provides requirements for planning and conducting an interlaboratory study to obtain data to develop single-operator and multilaboratory precision statements for a test method. It includes methods to evaluate data consistency before carrying out the calculations to develop the precision statement. The procedures are compatible with those in Practice E691.
4.2 The ILS data obtained from this practice are intended for developing the precision values for writing single-operator and multilaboratory precision statements in accordance with Practice C670.
4.3 Appendix X1 provides an example to illustrate the calculations to obtain the precision values of the test method from the ILS data. This may be used to check a user-developed electronic spreadsheet for carrying out the calculations.
4.4 Appendix X2 discusses the additional calculations required for an interlaboratory study of a test method that includes making test specimens as part of the procedure. In this case, batch-to-batch variability needs to be considered.
4.5 Appendix X3 discusses the use of analysis of variance as an alternative approach to obtain the precision values from the ILS data.
SCOPE
1.1 This practice describes techniques for planning, conducting, and analyzing the results of an interlaboratory study (ILS) with the objective of developing the precision statement of a test method. It is designed to be used in conjunction with Practice C670. The methods used in this standard are consistent with those in Practice E691.
1.2 This practice is not intended for use in programs whose purpose is to develop a test method or to assess the relative variability of two or more test methods. Refer to Practice C1067 for procedures to evaluate the ruggedness of a test method.
1.3 The system of units for this practice has not been specified. Dimensional quantities in the practice are presented only in examples of calculations.
1.4 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.
1.5 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: C802 − 14 (Reapproved 2022)
Standard Practice for
Conducting an Interlaboratory Test Program to Determine
the Precision of Test Methods for Construction Materials
This standard is issued under the fixed designation C802; 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* C136 Test Method for Sieve Analysis of Fine and Coarse
Aggregates
1.1 This practice describes techniques for planning,
C311/C311M Test Methods for Sampling and Testing Fly
conducting, and analyzing the results of an interlaboratory
Ash or Natural Pozzolans for Use in Portland-Cement
study (ILS) with the objective of developing the precision
Concrete
statement of a test method. It is designed to be used in
C670 Practice for Preparing Precision and Bias Statements
conjunction with Practice C670. The methods used in this
for Test Methods for Construction Materials
standard are consistent with those in Practice E691.
C1067 Practice for Conducting a Ruggedness Evaluation or
1.2 This practice is not intended for use in programs whose
Screening Program for Test Methods for Construction
purpose is to develop a test method or to assess the relative
Materials
variability of two or more test methods. Refer to Practice
E105 Guide for Probability Sampling of Materials
C1067 for procedures to evaluate the ruggedness of a test
E177 Practice for Use of the Terms Precision and Bias in
method.
ASTM Test Methods
E178 Practice for Dealing With Outlying Observations
1.3 The system of units for this practice has not been
specified. Dimensional quantities in the practice are presented E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to
only in examples of calculations.
Determine the Precision of a Test Method
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
3.1 Definitions:
mine the applicability of regulatory limitations prior to use.
3.1.1 For definitions of general statistical terms, refer to
1.5 This international standard was developed in accor-
Terminology E456.
dance with internationally recognized principles on standard-
3.1.2 For definitions of terms associated with precision of
ization established in the Decision on Principles for the
test methods for construction materials, refer to Practice C670.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
4. Significance and Use
Barriers to Trade (TBT) Committee.
4.1 This practice provides requirements for planning and
2. Referenced Documents conducting an interlaboratory study to obtain data to develop
single-operator and multilaboratory precision statements for a
2.1 ASTM Standards:
test method. It includes methods to evaluate data consistency
C109/C109M Test Method for Compressive Strength of
before carrying out the calculations to develop the precision
Hydraulic Cement Mortars (Using 2-in. or [50 mm] Cube
statement. The procedures are compatible with those in Prac-
Specimens)
tice E691.
4.2 The ILS data obtained from this practice are intended
This practice is under the jurisdiction of ASTM Committee C09 on Concrete
for developing the precision values for writing single-operator
and ConcreteAggregates.This practice was developed jointly byASTM Committee
C01, C09, D04, and D18, and is endorsed by all four committees.
and multilaboratory precision statements in accordance with
Current edition approved Oct. 1, 2022. Published October 2022. Originally
Practice C670.
approved in 1974. Last previous edition approved in 2014 as C802 – 14. DOI:
10.1520/C0802-14R22.
4.3 Appendix X1 provides an example to illustrate the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
calculations to obtain the precision values of the test method
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
from the ILS data.This may be used to check a user-developed
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. electronic spreadsheet for carrying out the calculations.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C802 − 14 (2022)
4.4 Appendix X2 discusses the additional calculations re- There should be a reasonable degree of certainty that the
quired for an interlaboratory study of a test method that single-operator variances are the same in different laboratories,
includesmakingtestspecimensaspartoftheprocedure.Inthis and that troublesome interactions do not exist. These condi-
case, batch-to-batch variability needs to be considered. tions are investigated in the initial analysis of the data of an
interlaboratory study, and are discussed further in 10.4.
4.5 Appendix X3 discusses the use of analysis of variance
as an alternative approach to obtain the precision values from
5.5 Facilities and procedures for procurement, preparation,
the ILS data.
and distribution of samples or test specimens must be avail-
able.
5. General Requirements
5.6 Selection of samples or test specimens must be done by
5.1 Certain criteria need to be met before undertaking an
a randomization process, and one person who is familiar with
interlaboratory study to determine the precision of a test
randomization procedures needs to be responsible for seeing
method. If some conditions are not met or are met
that an appropriate randomization technique is used. Refer to
incompletely, the program will become more complicated to
Practice E105.
administer and require more work and expense, or may result
in impaired information. The requirements outlined in this
5.7 The precision of the test method should be evaluated on
section are intended to ensure that the test method is free of
different materials with a range of the characteristic being
technical difficulties to the greatest extent possible before an
measured that encompasses the typical use of the method in
expensive and time-consuming interlaboratory study is under-
practice. (See 7.1 and 7.2.)
taken.
5.8 Adequate numbers of participating laboratories,
5.2 The first requirement is the existence of a valid and
operators, and materials must be available. Requirements in
well-written test method that has been developed in one
these areas are specified in Sections 6 and 7.
laboratory and has been subjected to ruggedness evaluation of
5.9 The entire interlaboratory test program should be devel-
the testing procedure and conditions as described in Practice
oped from the beginning with the help and advice of persons
C1067. As a result of the screening procedure and some
familiar with statistical procedures and with the materials
experience with the test method in the sponsoring laboratory
involved. The ASTM International Interlaboratory Study Pro-
and one or two others, a written version of the test method has
been developed (but not necessarily published as a standard) gram can support subcommittees in the development of preci-
sion statements by assisting in the design of an interlaboratory
that describes the test procedure in terms that can be followed
by a competent operator in any properly equipped laboratory. study, distribution of specimens or samples, data analysis, and
preparation of a draft research report. Additional information
Critical conditions that affect the test results need to be
identifiedandtheproperandrealisticdegreeofcontrolofthose about theASTM ILS program can be obtained from theASTM
Website.
conditions have to be specified in the description of the test
procedure.
5.9.1 Itmaynotalwaysbepossibletoobtainpeoplewhoare
5.2.1 The tolerances established for various conditions in a familiar with the materials involved and who have a sufficient
test method provide reasonable ranges for these conditions and
knowledge of the proper statistical techniques and their proper
recognize that precise values with small tolerances may not be use. In this case, the subcommittee should obtain the services
achievable in practice. Variations in test results due to varia-
of a statistician who has experience in practical work with data
tions in such conditions contribute to the total variation, which from materials testing, and provide that person with an
determines the precision of the test method. If the resulting
opportunity for learning something about the particular mate-
variation is so great that uncertainties in average values rials and test method involved. Planners of an interlaboratory
obtained by the test method are unacceptably high, the test
study need to avoid the pitfall of assuming that the use of
method itself is at fault and it will need to be improved or statistical analysis software programs necessarily results in
replaced by a better one. An expensive and time-consuming
special expertise in manipulating the data or interpreting the
interlaboratory study is not recommended for such a test results.
method.
5.10 It is important to bear in mind that estimates of the
5.2.2 Apparatus required for performing the test must be
precision of a test method are always based on a particular set
defined clearly and must be available or able to be produced. If
of data obtained at a particular time and precision values need
alternative apparatus is permitted, criteria need to be provided
to be kept up-to-date. As materials, apparatus, and conditions
on the performance requirements of the apparatus, such as by
change, and operators change or gain more experience, the
specifying acceptable limits of measurements on standard
characteristic precision of the results obtained may change,
reference materials.
especially if the test method is new. In some cases, it may be
5.3 Personnel in laboratories participating in the ILS should
desirable to conduct more tests at a later date (though not
have adequate experience with routine laboratory procedures
necessarily a repetition of the complete interlaboratory study)
so that they are competent to run the test. The importance of
in order to provide a check on estimates previously obtained
this requirement will vary with the complexity of the method
and either verify them or introduce revisions. When a subcom-
and the degree to which it departs from familiar procedures.
mittee revises a test method, it should consider whether the
5.4 It is helpful to have preliminary knowledge about how proposed changes might affect the precision of the method. If
changes in materials and conditions affect the test results. there is a possibility that precision will be affected, limited
C802 − 14 (2022)
interlaboratory testing is recommended to evaluate whether the 7.1.3 The difficulty and expense involved in obtaining,
existing precision statement is still applicable or if a new ILS processing, and distributing samples or specimens;
needs to be organized to better reflect the precision of the
7.1.4 The difficulty of, length of time required for, and
revised method. expense of performing the tests; and
7.1.5 The uncertainty of prior information on any of these
6. Laboratories
points. For example, if it is already known that the precision is
6.1 Obtaining participating laboratories for an interlabora- relatively constant or proportional to the average level over the
torystudyisoftenoneofthemostdifficultproblemsconnected
range of values of interest, a smaller number of materials will
with the process. The number of laboratories available is be needed than if it is known that the precision changes
seldom as extensive as one would like, and if the test method
erratically at different levels. A preliminary pilot or screening
is new, complicated, or expensive and time-consuming to run,
program may help to settle some of these questions, and may
the problem is further complicated.
often result in the saving of considerable time and expense in
the full interlaboratory study (1).
6.2 For the purposes of programs using this practice, it is
recommended that at least ten competent laboratories be
7.2 In general, at least three materials or three different
included (1, 2). In cases where it is impossible to obtain ten
average values of the measuredtest characteristicisconsidered
laboratories,theeffectofanincreasednumbermaybeobtained
acceptable.Thematerialsneedtobeselectedtoobtainasbroad
by repeating the program with the same group of laboratories
a range of the test characteristic as is practicable. If the test
sixmonthslater.Ifthisprocedureisfollowed,itisnecessaryto
method is used to determine properties that are used for
be sure that the same materials are used, and that their
acceptancetestinginaspecification,itisparticularlyimportant
characteristics have not changed in the interim. This approach,
that materials be included in the ILS whose properties are near
however, may not provide a proper measure of the between-
the specification limits.
laboratory component of variance, unless different operators or
7.3 Specimen Distribution—The ILS is based on the as-
equipment, or both, are used for the repeat testing. In any case,
sumption that all tests are performed on specimens that are as
six is the absolute minimum number of laboratories for
similar as is possible. Generally, two approaches are used for
evaluating the precision of a test method. This means that at
makinganddistributingthespecimensormaterialsfortheILS.
least seven to eight laboratories should be in the ILS study in
7.3.1 For a test method that does not involve production of
case problems are encountered with the data provided by a
the test specimens as part of the method, specimens are
participating laboratory.
produced at one location from a homogenous sample and then
6.3 In general, it is recommended that any laboratory that is
distributed to the participating laboratories. The specimens
considered qualified to run the test in routine testing situations
need to be assigned to the participating laboratories on a
should be permitted and encouraged to participate. “Qualified”
randombasis.Ifthecharacteristictobemeasuredchangeswith
implies proper laboratory facilities and testing equipment,
age, specific in
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