ASTM C802-96
(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
SCOPE
1.1 This practice describes techniques for planning, conducting, and analyzing the results of an interlaboratory study of a test method. It is designed to be used in conjunction with Practice C670. Thus, the procedures recommended in this practice have the limited purpose of providing reliable information on which precision statements of the type described in Practice C670 can be based. It is not appropriate for use in programs whose purpose is to develop a test method or to assess the relative merits of two or more test methods.
General Information
Relations
Buy Standard
Standards Content (Sample)
Designation:C802–96
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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope and expense, or may result in impaired information. The
recommendations outlined in this section are intended to
1.1 This practice describes techniques for planning, con-
ensurethatthetestmethodisfreeoftechnicaldifficultiestothe
ducting,andanalyzingtheresultsofaninterlaboratorystudyof
greatest extent possible before an expensive and time-
a test method. It is designed to be used in conjunction with
consuming interlaboratory study is undertaken.
Practice C670. Thus, the procedures recommended in this
3.1.1 The first requirement is the existence of a valid and
practice have the limited purpose of providing reliable infor-
well-written test method that has been developed in one
mation on which precision statements of the type described in
competent laboratory (or by cooperative work in a small
Practice C670 can be based. It is not appropriate for use in
number of laboratories), and has been subjected to a screening
programs whose purpose is to develop a test method or to
procedure, or to ruggedness testing as described in Practice
assess the relative merits of two or more test methods.
C1067. As a result of the screening procedure and some
2. Referenced Documents experience with the test method in the sponsoring laboratory
and one or two others, a written version of the test method has
2.1 ASTM Standards:
been developed (but not necessarily published as a standard
C109/C109M Test Method for Compressive Strength of
method) that describes the test procedure in terms that can
Hydraulic Cement Mortars (Using 2-in. or 50-mm Cube
easily be followed in any properly equipped laboratory. Con-
Specimens)
ditions that affect the test results should be identified and the
C136 Test Method for Sieve Analysis of Fine and Coarse
properdegreeofcontrolofthoseconditionsshouldbespecified
Aggregates
in the description of the test procedure (Note 1).
C670 Practice for Preparing Precision and Bias Statements
for Test Methods for Construction Materials
NOTE 1—The desired degree of control of conditions that affect test
C1067 Practice for Conducting a Ruggedness or Screening
resultsmaynotalwaysbepracticallyachievable,andtolerancesinthetest
Program for Test Methods for Construction Materials method should recognize this fact. Variations in test results due to
variations in such conditions contribute to the total variation which
E105 Practice for Probability Sampling of Materials
determines the precision of the test method. If the resulting variation is so
E177 Practice for Use of the Terms Precision and Bias in
great that uncertainties in average values obtained by the test method are
ASTM Test Methods
unacceptablyhigh,thenthetestmethoditselfisatfault,andeffortsshould
E178 Practice for Dealing with Outlying Observations
be made to improve it or to replace it by a better one. An expensive and
time-consuming interlaboratory study should not be undertaken on such a
3. Significance and Use
test method.
3.1 Certain criteria need to be met before undertaking an
3.1.2 Any apparatus required for performing the test should
interlaboratory study to determine the precision of a test
be appropriately designed and available at reasonable cost.
method. It is not necessary that all of the following conditions
3.1.3 Personnel in participating laboratories should have
described be completely fulfilled in every case; however, if
enough experience with the test method so that they are
some conditions are not met or are met incompletely, the
competent to run the test. The importance of this requirement
programwillbecomemorecomplicatedandrequiremorework
will vary with the complexity of the method and the degree to
which it departs from familiar procedures.
3.1.4 Preliminary knowledge should exist about how
This practice is under the jurisdiction of ASTM Committee C-9 on Concrete
changes in materials and conditions affect the test results.
andConcreteAggregates.ThispracticewasdevelopedjointlybyASTMCommittee
C-1, C-9, D-4, and D-18, and is endorsed by all four committees.
There should be a reasonable degree of certainty that the
Current edition approved May 10, 1996. Published July 1996. Originally
within-laboratory variances are the same in different laborato-
published as C802–74T. Last previous edition C802–94.
ries, and that troublesome interactions do not exist. These
Annual Book of ASTM Standards, Vol 04.01.
Annual Book of ASTM Standards, Vol 04.02.
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C802–96
conditions are investigated in the analysis of the data of an laboratories be included (1, 2). In cases where it is impossible
interlaboratory study, and are discussed further in 8.2.2, 8.2.3, to obtain ten laboratories, the effect of an increased number
and Appendix X1. maybeobtainedbyrepeatingtheprogramwiththesamegroup
of laboratories six months later. Usually, results obtained from
3.1.5 Facilities and procedures for procurement, prepara-
the same laboratory after a time lapse of approximately six
tion, and distribution of samples must be available and should
months display most of the characteristics of results from a
be as simple and free of difficulties as practicable.
different laboratory, especially if a different operator and
3.1.6 Selectionofsamplesmustbedonebyarandomization
apparatus can be used. If this procedure is followed, it is
process, and one person who is familiar with randomization
necessary to be sure that the same materials are used, and that
procedures should be responsible for seeing that the procedure
their characteristics have not changed in the interim.
is carried out. Refer to Recommended Practice E105.
4.3 In general, it is recommended that any laboratory that is
3.1.7 Adequate numbers of participating laboratories, op-
considered qualified to run the test in routine testing situations
erators,andmaterialsmustbeavailable.Requirementsinthese
should be permitted and encouraged to participate. “Qualified”
areas are specified in Sections 4 and 5.
implies proper laboratory facilities and testing equipment,
3.1.8 The entire interlaboratory test program should be
competentoperatorsfamiliarwiththetestmethod,areputation
developed from the beginning with the help and advice of
for reliable testing work, and sufficient time and interest to do
persons familiar with statistical procedures and with the
agoodjob.Itdoesnotmean,however,thatonlyaselectgroup
materials involved (Note 2).The same persons who design the
oflaboratoriesthatareconsideredtobethosebestqualifiedfor
experiment should also carry out, or at least have control over,
the interlaboratory study should be picked. Precision estimates
the process of analysis of the data.
for inclusion in a test method must be obtained under condi-
NOTE 2—It may not always be possible to obtain people who are tions and through the efforts of laboratories and personnel that
familiar with the materials involved who have a sufficient knowledge of
are representative of the situations in which the test method
the proper statistical techniques and their proper use. In this case, the
will be used in practice (3). If a laboratory has all the other
committee should obtain the services of a competent statistician who has
requirements, but its personnel has had insufficient experience
experienceinpracticalworkwithdatafrommaterialstesting,andprovide
with the method, the operators in that laboratory should be
him with an opportunity for learning something about the particular
givenanopportunitytofamiliarizethemselveswiththemethod
materials and test method involved. Planners of an interlaboratory study
and to practice its application before the interlaboratory study
should also be warned to avoid the pitfall of assuming that the use of a
large computer necessarily results in special expertise in the handling of starts.
data or the interpretation of results.
5. Materials
3.2 It is important to bear in mind that estimates of the
5.1 The number and type of materials to be included in an
precision of a test method are always based on a particular set
interlaboratory study will depend on the following:
of data obtained at a particular time and they need to be kept
5.1.1 The range of the values of the property being mea-
up-to-date.Asmaterials,apparatus,andconditionschange,and
sured on a given material and how the precision varies over
operators change or gain more experience, the characteristic
that range,
precision of the results obtained may change, especially if the
5.1.2 The number of different materials to which the test
test method is new. In some cases, it may even be desirable to
method is to be applied,
conduct more tests at a later date (though not necessarily a
5.1.3 The difficulty and expense involved in obtaining,
repetition of the complete interlaboratory study) in order to
processing, and distributing samples,
provide a check on estimates previously obtained and either
5.1.4 The difficulty of, length of time required for, and
verify them or introduce revisions.
expense of performing the tests, and
5.1.5 The uncertainty of prior information on any of these
4. Laboratories
points. For example, if it is already known that the precision is
4.1 The problem of obtaining competent participating labo-
relativelyconstantorproportionaltotheaverageleveloverthe
ratories for an interlaboratory study is often one of the most
range of values of interest, a smaller number of materials will
difficult ones connected with the process. The number of
be needed than if it is known that the precision changes
laboratoriesavailableisseldomasextensiveasonewouldlike,
erratically at different levels. A preliminary pilot or screening
and if the test method is new, complicated, or expensive and
program may help to settle some of these questions, and may
time-consuming to run, the problem is further complicated.
often result in the saving of considerable time and expense in
The problem usually becomes one of finding and obtaining the
the full interlaboratory study (4).
cooperation of enough qualified laboratories to obtain mean-
5.2 In general, a minimum of three materials should be
ingful estimates of precision, rather than that of selection
considered acceptable.
among a group of available laboratories. If there is great
6. Estimates of Precision
difficulty in obtaining a sufficient number of competent and
6.1 In accordance with Recommended Practice C670, the
willing laboratories, then the possibility exists that the test
procedure described in this practice is designed to provide two
method should not be subjected to a formal interlaboratory
study.
4.2 For the purposes of programs using this recommended
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
practice, it is recommended that at least ten participating this practice.
C802–96
basic estimates of the precision of a test method: (a) single- Reporting(seeX1.3.1).Thisisnecessarybecausethevariation
operator precision, and (b) multilaboratory precision. If other from which information about the precision of the test method
estimates of precision are desired, other references should be comes is contained in the least significant digits, which are
consulted (see Practice E177) (5). often discarded in reporting the results of routine testing (6).
6.2 Single-operator precision provides an estimate of the For example, Method C136 calls for reporting of percentages
difference that may be expected between duplicate measure- to the nearest whole number. This is adequate for the usual
mentsmadeonthesamematerialinthesamelaboratorybythe reporting purposes, but for purposes of determining precision,
same operator using the same apparatus within a time span of at least one decimal place is needed. It is better to require the
a few days. reporting of too many decimal places than too few, since a
6.3 Multilaboratory precision provides an estimate of the decisionaboutroundingalldatacanbemadewhentheanalysis
difference that may be expected between measurements made is done. If too few places are reported, however, valuable
on the same material in two different laboratories. informationmaybeirretrievablylost,andtheresultmightwell
be the impairment of the entire program.
7. Collection of Data
7.2.2.2 In cases where a test result is the result of a
calculation based on two or more measured quantities, the
7.1 In order to minimize the problems concerned with
analysis of data, a definite form and instructions for obtaining basic measurements should be used in the calculations without
anyrounding.Theplannersoftheinterlaboratoryprogramwill
and recording the data should be developed and distributed to
all participating laboratories. thenhavetodeterminehowmanyplacesneedtobereportedin
order to retain the essential information for determining
7.2 Directions to Laboratories—The directions to the labo-
ratories should deal mainly with reporting of data. No special variability. Sometimes it is advisable to ask the laboratories to
report the basic quantities measured instead of, or in addition
instructions for performing the tests that differ from those
given in the description of the test method should be included. to, the final calculated result.This enables the final result to be
checked, or changes in decisions about the test results to be
The laboratories should be cautioned to conduct tests and
made,whenthedataareanalyzed.Thisprocedureisespecially
report results exactly as specified in the test method, with the
appropriate if the results are to be analyzed by computer, and
one exception as noted in 7.2.2.
the program can be utilized to perform the basic calculations
7.2.1 Averaging Test Results—Laboratories should particu-
and analyze the calculated results.
larly be cautioned against practices such as running a number
of tests and selecting the “best” ones or reporting the average 7.3 The Data Sheet—Thispracticeisbasedonthefollowing
assumptions: p laboratories each have made n replicate mea-
ofseveraldeterminations,exceptassuchaveragingisspecified
in the test method. For example, Test Method C109 specifies surementsoneachof qmaterials(seeRef 7).Table1andTable
three or more test specimens, and requires that the strength of 2 are sample data sheets for an individual laboratory and for a
summary of data for the entire program for a program wi
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:C802–09 Designation:C802–96
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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope *
1.1 This practice describes techniques for planning, conducting, and analyzing the results of an interlaboratory study of a test
method.ItisdesignedtobeusedinconjunctionwithPracticeC670C670.Thus,theproceduresrecommendedinthispracticehave
the limited purpose of providing reliable information on which precision statements of the type described in Practice C670C670
can be based. It is not appropriate for use in programs whose purpose is to develop a test method or to assess the relative merits
of two or more test methods.
1.2The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
2. Referenced Documents
2.1 ASTM Standards:
C109/C109M Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50-mm]50-mm Cube
Specimens)
C136 Test Method for Sieve Analysis of Fine and Coarse Aggregates
C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
C1067 Practice for Conducting Aa Ruggedness or Screening Program for Test Methods for Construction Materials
E105 Practice for Probability Sampling of Materials
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E178 Practice for Dealing Withwith Outlying Observations
3. Significance and Use
3.1 Certain criteria need to be met before undertaking an interlaboratory study to determine the precision of a test method. It
is not necessary that all of the following conditions described be completely fulfilled in every case; however, if some conditions
arenotmetoraremetincompletely,theprogramwillbecomemorecomplicatedandrequiremoreworkandexpense,ormayresult
in impaired information. The recommendations outlined in this section are intended to ensure that the test method is free of
technical difficulties to the greatest extent possible before an expensive and time-consuming interlaboratory study is undertaken.
3.1.1 The first requirement is the existence of a valid and well-written test method that has been developed in one competent
laboratory (or by cooperative work in a small number of laboratories), and has been subjected to a screening procedure, or to
ruggedness testing as described in Practice C1067C1067. As a result of the screening procedure and some experience with the
test method in the sponsoring laboratory and one or two others, a written version of the test method has been developed (but not
necessarily published as a standard method) that describes the test procedure in terms that can easily be followed in any properly
equippedlaboratory.Conditionsthataffectthetestresultsshouldbeidentifiedandtheproperdegreeofcontrolofthoseconditions
should be specified in the description of the test procedure (see (Note 1).
This practice is under the jurisdiction ofASTM Committee C09 on Concrete and ConcreteAggregates .This practice was developed jointly byASTM Committee C01,
C09, D04, and D18, and is endorsed by all four committees.
´1
Current edition approved Nov. 1, 2009. Published December 2009. Originally approved in 1974. Last previous edition approved in 2008 as C802–96(2008) . DOI:
10.1520/C0802-09.
This practice is under the jurisdiction ofASTM Committee C-9 on Concrete and ConcreteAggregates. This practice was developed jointly byASTM Committee C-1,
C-9, D-4, and D-18, and is endorsed by all four committees.
Current edition approved May 10, 1996. Published July 1996. Originally published as C802–74T. Last previous edition C802–94.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For
Annual Book of ASTM Standardsvolume information, refer to the standard’s Document Summary page on the ASTM website., Vol 04.01.
The boldface numbers in parentheses refer to the list of references at the end of this practice.
Annual Book of ASTM Standards, Vol 04.02.
Annual Book of ASTM Standards, Vol 14.02.
*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.
C802–96
NOTE 1—Thedesireddegreeofcontrolofconditionsthataffecttestresultsmaynotalwaysbepracticallyachievable,andtolerancesinthetestmethod
should recognize this fact. Variations in test results due to variations in such conditions contribute to the total variation which determines the precision
of the test method. If the resulting variation is so great that uncertainties in average values obtained by the test method are unacceptably high, then the
test method itself is at fault, and efforts should be made to improve it or to replace it by a better one.An expensive and time-consuming interlaboratory
study should not be undertaken on such a test method.
3.1.2 Any apparatus required for performing the test should be appropriately designed and available at reasonable cost.
3.1.3 Personnel in participating laboratories should have enough experience with the test method so that they are competent to
run the test. The importance of this requirement will vary with the complexity of the method and the degree to which it departs
from familiar procedures.
3.1.4 Preliminary knowledge should exist about how changes in materials and conditions affect the test results. There should
beareasonabledegreeofcertaintythatthewithin-laboratoryvariancesarethesameindifferentlaboratories,andthattroublesome
interactionsdonotexist.Theseconditionsareinvestigatedintheanalysisofthedataofaninterlaboratorystudy,andarediscussed
further in 8.2.2, 8.2.3, and Appendix X1.
3.1.5 Facilities and procedures for procurement, preparation, and distribution of samples must be available and should be as
simple and free of difficulties as practicable.
3.1.6 Selection of samples must be done by a randomization process, and one person who is familiar with randomization
procedures should be responsible for seeing that the procedure is carried out. Refer to Recommended Practice E105E105.
3.1.7 Adequate numbers of participating laboratories, operators, and materials must be available. Requirements in these areas
are specified in Sections 4 and 5.
3.1.8 The entire interlaboratory test program should be developed from the beginning with the help and advice of persons
familiar with statistical procedures and with the materials involved (see (Note 2). The same persons who design the experiment
should also carry out, or at least have control over, the process of analysis of the data.
NOTE 2—It may not always be possible to obtain people who are familiar with the materials involved who have a sufficient knowledge of the proper
statisticaltechniquesandtheirproperuse.Inthiscase,thecommitteeshouldobtaintheservicesofacompetentstatisticianwhohasexperienceinpractical
work with data from materials testing, and provide him with an opportunity for learning something about the particular materials and test method
involved.Plannersofaninterlaboratorystudyshouldalsobewarnedtoavoidthepitfallofassumingthattheuseofstatisticalanalysissoftwareprogramsa
large computer necessarily results in special expertise in the handling of data or the interpretation of results.
3.2 It is important to bear in mind that estimates of the precision of a test method are always based on a particular set of data
obtained at a particular time and they need to be kept up-to-date. As materials, apparatus, and conditions change, and operators
change or gain more experience, the characteristic precision of the results obtained may change, especially if the test method is
new. In some cases, it may even be desirable to conduct more tests at a later date (though not necessarily a repetition of the
complete interlaboratory study) in order to provide a check on estimates previously obtained and either verify them or introduce
revisions.
4. Laboratories
4.1 The problem of obtaining competent participating laboratories for an interlaboratory study is often one of the most difficult
ones connected with the process. The number of laboratories available is seldom as extensive as one would like, and if the test
method is new, complicated, or expensive and time-consuming to run, the problem is further complicated. The problem usually
becomesoneoffindingandobtainingthecooperationofenoughqualifiedlaboratoriestoobtainmeaningfulestimatesofprecision,
rather than that of selection among a group of available laboratories. If there is great difficulty in obtaining a sufficient number of
competent and willing laboratories, then the possibility exists that the test method should not be subjected to a formal
interlaboratory study.
4.2 Forthepurposesofprogramsusingthisrecommendedpractice,itisrecommendedthatatleasttenparticipatinglaboratories
be included (1, 2). In cases where it is impossible to obtain ten laboratories, the effect of an increased number may be obtained
by repeating the program with the same group of laboratories six months later. Usually, results obtained from the same laboratory
after a time lapse of approximately six months display most of the characteristics of results from a different laboratory, especially
if a different operator and apparatus can be used. If this procedure is followed, it is necessary to be sure that the same materials
are used, and that their characteristics have not changed in the interim.
4.3 In general, it is recommended that any laboratory that is considered qualified to run the test in routine testing situations
should be permitted and encouraged to participate. “Qualified” implies proper laboratory facilities and testing equipment,
competent operators familiar with the test method, a reputation for reliable testing work, and sufficient time and interest to do a
good job. It does not mean, however, that only a select group of laboratories that are considered to be those best qualified for the
interlaboratory study should be picked. Precision estimates for inclusion in a test method must be obtained under conditions and
through the efforts of laboratories and personnel that are representative of the situations in which the test method will be used in
practice (3). If a laboratory has all the other requirements, but its personnel has had insufficient experience with the method, the
operatorsinthatlaboratoryshouldbegivenanopportunitytofamiliarizethemselveswiththemethodandtopracticeitsapplication
before the interlaboratory study starts.
The boldface numbers in parentheses refer to the list of references at the end of this practice.
C802–96
5. Materials
5.1 The number and type of materials to be included in an interlaboratory study will depend on the following:
5.1.1 The range of the values of the property being measured on a given material and how the precision varies over that range,
5.1.2 The number of different materials to which the test method is to be applied,
5.1.3 The difficulty and expense involved in obtaining, processing, and distributing samples,
5.1.4 The difficulty of, length of time required for, and expense of performing the tests, and
5.1.5 The uncertainty of prior information on any of these points. For example, if it is already known that the precision is
relatively constant or proportional to the average level over the range of values of interest, a smaller number of materials will be
needed than if it is known that the precision changes erratically at different levels.Apreliminary pilot or screening program may
helptosettlesomeofthesequestions,andmayoftenresultinthesavingofconsiderabletimeandexpenseinthefullinterlaboratory
study (4).
5.2 In general, a minimum of three materials should be considered acceptable.
6. Estimates of Precision
6.1 InaccordancewithRecommendedPracticeC670C670,theproceduredescribedinthispracticeisdesignedtoprovidetwo
basicestimatesoftheprecisionofatestmethod:( a)single-operatorprecision,and(b)multilaboratoryprecision.Ifotherestimates
of precision are desired, other references should be consulted (see Practice E177E177) (5).
6.2 Single-operator precision provides an estimate of the difference that may be expected between duplicate measurements
madeonthesamematerialinthesamelaboratorybythesameoperatorusingthesameapparatuswithinatimespanofafewdays.
6.3 Multilaboratory precision provides an estimate of the difference that may be expected between measurements made on the
same material in two different laboratories.
7. Collection of Data
7.1 In order to minimize the problems concerned with analysis of data, a definite form and instructions for obtaining and
recording the data should be developed and distributed to all participating laboratories.
7.2 Directions to Laboratories—The directions to the laboratories should deal mainly with reporting of data. No special
instructions for performing the tests that differ from those given in the description of the test method should be included. The
laboratories should be cautioned to conduct tests and report results exactly as specified in the test method, with the one exception
as noted in 7.2.2.
7.2.1 Averaging Test Results—Laboratoriesshouldparticularlybecautionedagainstpracticessuchasrunninganumberoftests
and selecting the “best” ones or reporting the average of several determinations, except as such averaging is specified in the test
method. For example, Test Method C109C109/C109M specifies three or more test specimens, and requires that the strength of
allacceptabletestspecimensmadefromthesamesampleandtestedatthesameperiodshallbeaveragedandreported.Inthiscase,
the directions for the interlaboratory test should specify the number of determinations to be obtained and reported. Whenever a
test result is defined, either in the test method or in the instructions to laboratories participating in an interlaboratory test program,
as the average of a particular number of determinations, the individual deter
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.