ASTM C802-96(2002)

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 C 670. 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 C 670 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

• Status: Historical
• Publication Date: 09-May-1996
• ICS: 91.100.01 - Construction materials in general
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.94 - Evaluation of Data (Joint C09 and C01)

Relations

• Replaces: ASTM C802-96 - Standard Practice for Conducting an Interlaboratory Test Program to Determine the Precision of Test Methods for Construction Materials
• Effective Date: 10-May-1996
• Replaced By: ASTM C802-96(2008)e1 - Standard Practice for Conducting an Interlaboratory Test Program to Determine the Precision of Test Methods for Construction Materials
• Effective Date: 01-Dec-2008
• Referred By: ASTM C670-15 - Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
• Effective Date: 10-May-1996
• Referred By: ASTM D6648-08(2016) - Standard Test Method for Determining the Flexural Creep Stiffness of Asphalt Binder Using the Bending Beam Rheometer (BBR)
• Effective Date: 10-May-1996
• Referred By: ASTM C1077-17 - Standard Practice for Agencies Testing Concrete and Concrete Aggregates for Use in Construction and Criteria for Testing Agency Evaluation
• Effective Date: 10-May-1996
• Referred By: ASTM D6607-21 - Standard Practice for Inclusion of Precision Statement Variation in Specification Limits
• Effective Date: 10-May-1996
• Referred By: ASTM D653-22 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 10-May-1996
• Referred By: ASTM C403/C403M-23 - Standard Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance
• Effective Date: 10-May-1996
• Referred By: ASTM C1067-20 - Standard Practice for Conducting a Ruggedness Evaluation or Screening Program for Test Methods for Construction Materials
• Effective Date: 10-May-1996
• Referred By: ASTM C796/C796M-19 - Standard Test Method for Foaming Agents for Use in Producing Cellular Concrete Using Preformed Foam
• Effective Date: 10-May-1996
• Referred By: ASTM C1202-22e1 - Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration
• Effective Date: 10-May-1996

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:C802–96 (Reapproved 2002)
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 (see 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 C09 on Concrete
andConcreteAggregates.ThispracticewasdevelopedjointlybyASTMCommittee
changes in materials and conditions affect the test results.
C01, C09, D04, and D18, 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 (2002)
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 (see Note 2).The same persons who design
oflaboratoriesthatareconsideredtobethosebestqualifiedfor
the experiment should also carry out, or at least have control
the interlaboratory study should be picked. Precision estimates
over, 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 (2002)
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/C109M surementsoneachof qmaterials(seeRef 7).
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