ASTM C1067-00(2007)
(Practice)Standard Practice for Conducting A Ruggedness or Screening Program for Test Methods for Construction Materials
Standard Practice for Conducting A Ruggedness or Screening Program for Test Methods for Construction Materials
SCOPE
1.1 This practice covers a procedure for detecting sources of variation in a test method. The procedure should be used during the development of a test method, before the interlaboratory study is executed, such as those in Practices C 670, C 802, and E 691. Interlaboratory studies can be expensive to execute. Resources will probably be more efficiently used if sources of variation in a test method are eliminated prior to performing the interlaboratory study. The procedure also is useful for determining sources of variation in an existing test method that has been found to have poor precision.
1.2 This practice covers, in very general terms, techniques for planning, collecting data, and analyzing results from a few laboratories. provides the details of the procedure with an example and gives the theoretical background.
1.3 The practice does not give information pertinent to estimating within- or between-laboratory precision.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:C1067–00 (Reapproved 2007)
Standard Practice for
Conducting A Ruggedness or Screening Program for Test
Methods for Construction Materials
This standard is issued under the fixed designation C1067; 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 C802 Practice for Conducting an Interlaboratory Test Pro-
gram to Determine the Precision of Test Methods for
1.1 Thispracticecoversaprocedurefordetectingsourcesof
Construction Materials
variationinatestmethod.Theprocedureshouldbeusedduring
E456 Terminology Relating to Quality and Statistics
the development of a test method, before the interlaboratory
E691 Practice for Conducting an Interlaboratory Study to
study is executed, such as those in Practices C670, C802, and
Determine the Precision of a Test Method
E691. Interlaboratory studies can be expensive to execute.
E1169 Practice for Conducting Ruggedness Tests
Resources will probably be more efficiently used if sources of
variation in a test method are eliminated prior to performing
3. Terminology
the interlaboratory study. The procedure also is useful for
3.1 Definitions:
determiningsourcesofvariationinanexistingtestmethodthat
3.1.1 determination value, n—numericalquantitycalculated
has been found to have poor precision.
as directed in the test method using direct measurements
1.2 This practice covers, in very general terms, techniques
obtained in accordance with the procedures given in the test
for planning, collecting data, and analyzing results from a few
method.
laboratories. Annex A1 provides the details of the procedure
3.1.2 replication, n—the act of obtaining two or more
with an example and Annex A2 gives the theoretical back-
determination values under specified conditions. The number
ground.
of replications must be finite and the scope of the replication
1.3 The practice does not give information pertinent to
operation may be narrow or broad, but must be specified.
estimating within- or between-laboratory precision.
3.1.3 For definitions of other statistical terms used in this
1.4 This standard does not purport to address all of the
standard, refer to Terminology E456.
safety concerns, if any, associated with its use. It is the
3.2 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.2.1 factor, n—an element in the test procedure or labora-
priate safety and health practices and determine the applica-
tory environment that is a potential source of variation in test
bility of regulatory limitations prior to use.
results.
2. Referenced Documents 3.2.2 ruggedness, adj—the characteristic of a test method
2 that produces test results that are not influenced by small
2.1 ASTM Standards:
differences in the testing procedure or environment.
C670 Practice for Preparing Precision and Bias Statements
3.2.3 screening, n—the detection of significant sources of
for Test Methods for Construction Materials
variation as compared to chance variation.
3.2.4 variable, n—a number or quantity that varies.
This practice is under the jurisdiction of ASTM Committee C09 on Concrete
and ConcreteAggregates . This practice was developed jointly byASTM Commit- 4. Summary of Practice
tees C01, C09, D04, and D18, and is endorsed by all four committees.
4.1 The practice requires that the user develop, from theo-
Current edition approved June 1, 2007. Published October 2007. Originally
retical or practical knowledge, or both, a list of factors that
approved in 1987. Last previous edition approved in 2000 as C1067–00. DOI:
10.1520/C1067-00R07.
plausibly would cause significant variation in test results if the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
factors were not controlled. The technique is limited to the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
analysis of the effects seven factors and requires considerably
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. less effort than would be required to collected data for seven
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C1067–00 (2007)
factors in a full factorial study. Procedures exist for analysis of problems in the clarity of the test method directions. Two
smaller and larger numbers of factors (see Guide E1169), but additional laboratories will probably contribute fresh critical
seven is a convenient number for many test methods for reviewofthevalidityofthetestmethodandprovideassistance
construction materials. The seven-factor analysis requires 16 in clarifying the instructions of the test method when needed.
determinations by each laboratory. The procedure can be
6. Materials
usefully executed by a single laboratory, but sometimes addi-
tionalinformationcanbeobtainedifitisrepeatedinoneortwo
6.1 The number and types of material shall cover the range
additional laboratories.
of material properties to which the test method is applicable.
4.2 The procedure requires that two levels of each factor be
The test method does not apply to material types or property
identified, then 16 determinations be done on a prescribed
values outside the range evaluated.Three to five materials will
combinations of factor levels. The levels assigned to a factor
usually be sufficient.
may be quantitative or qualitative (for example, brass versus
6.1.1 Some preliminary testing may help the laboratories
steel).
involved determine the materials that shall be used in the
4.3 The disadvantage of this type of analysis is that the
screening program.
method only estimates simple effects of each factor and does
not detect interactive effects among factors.
7. Procedure
7.1 Determine the number of laboratories that will partici-
5. Significance and Use
pate in the program and which materials each will use in the
5.1 The purpose of a ruggedness evaluation is to determin-
program. The maximum amount of information is obtained if
ing how sensitive the test method is to changes in levels of
all laboratories include all materials in their part of the
pertinent operating factors. Normally, operating conditions for
program, however cost can be reduced by each laboratory
a test method are defined along with an allowable tolerance.A
using a different material. Caution must be exercised in
ruggedness analysis determines that effect of worst-case varia-
interpreting the results since laboratory-dependent cannot be
tion in operating conditions within this tolerance range. The
separated from material-dependent effects.
method then can be revised with smaller tolerances on operat-
7.2 Factors that are likely to have the greatest effect on the
ing conditions to improve the precision.
variability in the test results are selected for study. Levels of
5.2 Amajor reason for poor precision in test methods is the
these factors are determined, selecting the minimum and
lackofadequatecontroloverthesourcesofvariationintesting
maximumlevelsthatwouldplausiblyoccurintheexecutionof
procedures or testing environments.These sources of variation
the test method if there were no particular efforts to control
often are not controlled adequately because they were not
them. Only two levels are allowed. Levels often represent
identified during the development of the test procedures.
quantitative properties, such as temperature, pressure, etc, but
5.3 All new test methods must be subjected to an interlabo-
they may also represent nonquantitative values, such as old vs
ratoryprogramforpurposesofdevelopingaprecisionandbias
new,wetvsdry,etc.Inthisstandard,factorsareassignedletter
statement. These programs can be expensive and lengthy, and
designations, A– G, and the two levels of each factor are
the result may be that the determination is made that the
designated with upper and lower cases of these letters, as in
methodistoovariabletobepublishedwithoutfurtherrevision.
Table 1.
Interlaboratory studies typically give the subcommittee an
7.3 Assign combinations of factor levels to experimental
indication that the method is too variable, but they do not
determinationsaccordingtoTable1.The8determinationswill
usually give a clear picture of what is causing the variation.
be done in duplicate, therefore, the full study on each material
Application of this ruggedness practice using one or a few
will require 16 determinations.
laboratoriesmaybeamuchmoreeconomicalwaytodetermine
7.4 Constructa16rowby16columnresultsmatrixfromthe
these causes.
16 determinations values (d – d ) as shown in Table 2. The
1 16
5.4 Many existing test methods were published before there
absolutevaluesofthedeterminationsineachrowareidentical,
was a requirement that precision and bias statements be
onlythesignsvary.Calculate Zand Wstatisticsasshowninthe
developed. Since this became a requirement, most of these test
equations below.
methodshavedevelopedprecisionandbiasstatements,andthe
result is that many have been found to suffer from relatively
Z 5 d,where d 8sarethe16resultsineachrow ~r!. (1)
(
r 1 i i
large amount of variation. Use of this practice represents a
relatively simple way to investigate the causes of variation in
test methods, so that a subcommittee will have some guidance
TABLE 1 Pattern of Assigning Levels to Seven Factors
as to which parts of the test method need to be studied further
Determination Number
for revision.
Factor 1 2 3 4 5 6 7 8
5.5 Theprocedurecanbeusedforaprogramwithinasingle
A aaa a A A A A
laboratory, but involvement of at least three laboratories is
B b bBB b bB B
recommended, particularly if the single laboratory were to be
C C cC c C cCc
the one in which the test method was developed. This is DD D d d d d D D
Ee E e E E e E e
particularly important for new test methods. The originating
F F ff F F ff F
laboratory is so much a part of the development of the test
GG g g G g G G g
method that it is difficult for it to be objective in spotting any
C1067–00 (2007)
TABLE 2 Results Matrix of 16 Determinations (d – d )
1 16
Eight Determinations for Replicate Set 1 Eight Determinations for Replicate Set 2
row 1234567812345678 ZW
1 d d d d d d d d d d d d d d d d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 1
2 d d d d –d –d –d –d d d d d –d –d –d –d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 2 2
3 d d –d –d d d –d –d d d –d –d d d –d –d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 3 3
4 d –d d –d d –d d –d d –d d –d d –d d –d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 4 4
5 d d –d –d –d –d d d d d –d –d –d –d d d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 5 5
6 d –d d –d –d d –d d d –d d –d –d d –d d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 6 6
7 d –d –d d d –d –d d d –d –d d d –d –d d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 7 7
8 d –d –d d –d d d –d d –d –d d –d d d –d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 8 8
9 d d d d d d d d –d –d –d –d –d –d –d –d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 9 9
10 d d d d –d –d –d –d –d –d –d –d d d d d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 10 10
11 d d –d –d d d –d –d –d –d d d –d –d d d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 11 11
12 d –d d –d d –d d –d –d d –d d –d d –d d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 12 12
13 d d –d –d –d –d d d –d –d d d d d –d –d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 13 13
14 d –d d –d –d d –d d –d d –d d d –d d –d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 14 14
15 d –d –d d d –d –d d –d d d –d –d d d –d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 15 15
16 d –d –d d –d d d –d –d d d –d d –d –d d Z W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 16 16
TABLE 3 Summary of Statistics for Seven Factors and Random
Z
Error
r
W 5 (2)
r
FactorWF
7.5 The W statistic for row 1 represents the simple sum of
A W W /X
2 2
B W W /X
the determinations and are not used in this analysis. Statistics 3 3
C W W /X
4 4
for rows 2–8 (W – W ) represent the effects of the seven
2 8
E W W /X
5 5
factors.Thestatisticforrow9(W )representthetotalvariation
9 F W W /X
6 6
G W W /X
between the two replicate sets and is not used in this analysis. 7 7
H W W /X
8 8
Statistics for rows 10 through 16 (W – W ) are used to
10 16
W
calculatetheerrorvariance(X),whichthenisusedtocalculate
W
W
the test criterion (F) for each factor, as shown by the equations 12
W X = ((W )/7, for W
13 10-16
below. Calculations are summarized in Table 3.
W
16 W
W
X 5 ~ W !/7 (3) 16
(
r
r510
W
r
F 5 , where F is the F statistic for the effect of factor
f f
7.7 An example of an analysis of data representing results
X
f (1–7, represented by W – W , respectively) on 4 materials from 3 laboratories is shown in Annex A1.
2 8
7.6 A F value of$5.59 represents a significant effect for
8. Keywords
factor f at a probability of 5% for drawing an erroneous
conclusion. 8.1 precision; ruggedness; test method; variation
ANNEXES
(Mandatory Information)
A1. EXAMPLE OF A RUGGEDNESS PROGRAM
A1.1 This annex describes the procedure for conducting a A1.2.3 Topickmaterialsthatcovertherangeoftheproperty
ruggednessevaluationusingasanexampleadescriptionofthe ofinterestfortherangeofphysicalformsofthematerialstobe
ruggednessevaluationonatestmethodforthemeasurementof tested, and
the viscosity of asphalt. A1.2.4 To determine the proper levels to be evaluated for
each of the chosen variables.
A1.2 As the first step in the ruggedness evaluation, each of
the laboratories critically examined the procedure in the
A1.3 In this example, representatives of the three labora-
proposed test method. The objectives of the examination were
tories, after familiarizing themselves with the test method as
as follows:
specified inA1.2, met and tried to improve the instructions for
A1.2.1 To determine if the instructions are clear, concise, the viscosity method. They selected variables, materials, and
and complete, levels that showed the effect of the variation. One of the
A1.2.2 To decide which factors are likely to influence test laboratoriesmeasuredviscosityat24°C,25°C,and26°Cand
results and therefore should be included in the study, found that there was about a 10% variation with a change of
C1067–00 (2007)
1 °C. This was considered too large so 24.6 and 25.4 °C were Table A1.6 to obtain the corresponding entry in column two
selected as the lower and upper temperature levels for the and then divide each entry in column two of TableA1.6 by 16
ruggedness test. In the same manner, the effect of the other to obtain the correspond
...
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