ASTM D4855-97(2002)

Standard Practice for Comparing Test Methods (Withdrawn 2008)

SIGNIFICANCE AND USE
Task groups developing a test method frequently find themselves with two or more alternative procedures that must be compared. Three common situations are:
4.1.1 Two or more new test methods may have been proposed to measure a property for which there is no existing method.
4.1.2 A new test method may have been suggested to replace an existing test method.
4.1.3 Two or more existing test methods may overlap in their scopes so that one should be chosen over the other.
The selection of one test method in preference to another is not simply a statistical choice. There are many other aspects of two test methods that should be considered, which may have an influence (on the engineering judgment of the task group) equal to or greater than the statistical evidence. Some of these characteristics are discussed in Section 6.
SCOPE
1.1 This practice provides a procedure for evaluating and comparing test methods under controlled conditions using the same materials tested during the same time span. The practice describes how to obtain and compare estimates on precision, sensitivity, and bias.
1.2 This practice covers the following topics:Topic TitleSection numberScope1Referenced Documents2Terminology3Significance and Use4Requirements for Materials5Evaluating Test Methods6Sensitivity Criterion7Basic Statistical Design8Experimental Procedure9Procedure for Comparing Precision10Evaluating the Bias Between Test Methods11Procedure for Comparing Sensitivities12Report13
WITHDRAWN RATIONALE
This practice provides a procedure for evaluating and comparing test methods under controlled conditions using the same materials tested during the same time span. The practice describes how to obtain and compare estimates on precision, sensitivity, and bias.
This practice is being withdrawn with no replacement because D13 no longer has the expertise to maintain and statistical standards are being maintained by committee E11.  
Formerly under the jurisdiction of Committee D13 on Textiles, this practice was withdrawn in July 2008.

General Information

• Status: Withdrawn
• Publication Date: 09-Sep-1997
• Withdrawal Date: 16-Oct-2008
• ICS: 59.080.01 - Textiles in general
• Technical Committee: D13 - Textiles

Relations

• Replaces: ASTM D4855-97 - Standard Practice for Comparing Test Methods
• Effective Date: 10-Sep-1997
• Referred By: ASTM E1655-17 - Standard Practices for Infrared Multivariate Quantitative Analysis
• Effective Date: 10-Sep-1997
• Referred By: ASTM B249/B249M-22 - Standard Specification for General Requirements for Wrought Copper and Copper-Alloy Rod, Bar, Shapes and Forgings
• Effective Date: 10-Sep-1997

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:D4855–97 (Reapproved 2002)
Standard Practice for
1
Comparing Test Methods
This standard is issued under the fixed designation D4855; 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.
statements on the relative merits of the two test methods are part of the
1. Scope
output.
1.1 This practice provides a procedure for evaluating and
comparing test methods under controlled conditions using the
3. Terminology
same materials tested during the same time span. The practice
3.1 Definitions:
describes how to obtain and compare estimates on precision,
3.1.1 accuracy, n—of a test method, the degree of agree-
sensitivity, and bias.
ment between the true value of the property being tested (or an
1.2 This practice covers the following topics:
acceptedstandardvalue)andtheaverageofmanyobservations
Topic Title Section
made according to the test method, preferably by many
number
observers. (See also bias and precision.)
Scope 1
3.1.1.1 Discussion—Increased accuracy is associated with
Referenced Documents 2
decreased bias relative to the true value; two methods with
Terminology 3
equal bias relative to the true value have equal accuracy even
Significance and Use 4
Requirements for Materials 5
if one method is more precise than the other. The true value is
Evaluating Test Methods 6
the exact value of the property being tested for the statistical
Sensitivity Criterion 7
universe being sampled. When the true value is not known or
Basic Statistical Design 8
Experimental Procedure 9
cannot be determined, and an acceptable standard value is not
Procedure for Comparing Precision 10
available, accuracy cannot be established. No valid inferences
Evaluating the Bias Between Test Methods 11
on the accuracy of a method can be drawn from an individual
Procedure for Comparing Sensitivities 12
Report 13
observation.
3.1.2 bias, n—in statistics, a constant or systematic error in
2. Referenced Documents
test results.
2.1 ASTM Standards:
3.1.2.1 Discussion—Bias can exist between the accepted
2
D123 Terminology Relating to Textiles
reference value and a test result obtained from one method,
D2905 Practice for Statements on Number of Specimens
between test results obtained from two methods, or between
2
for Textiles
two test results obtained from a single method, for example,
D2906 Practice for Statements on Precision and Bias for
between operators or between laboratories.
2
Textiles
3.1.3 confidence interval, n—the interval estimate of a
3
E456 Terminology Relating to Quality and Statistics
population parameter computed so that the statement “the
2.2 ASTM Adjuncts:
population parameter lies in this interval” will be true, on the
4
TEX-PAC
average, in a stated proportion of the times such statements are
made.
NOTE 1—Tex-Pac is a group of PC programs on floppy disks, available
throughASTM Headquarters, 100 Barr Harbor Drive, Conshohocken, PA
3.1.4 confidence level, n—the stated proportion of times the
19428,USA.Thecalculationsforcomparingtheprecision,sensitivityand
confidence interval is expected to include the population
bias of two test methods can be done using one of these programs and
parameter.
3.1.4.1 Discussion—Statisticians generally accept that, in
the absence of special consideration, 0.95 or 95% is a realistic
1
ThispracticeisunderthejurisdictionofASTMCommitteeD13onTextilesand
confidence level. If the consequences of incorrectly estimating
is the direct responsibility of Subcommittee D13.93 on Statistics.
the confidence interval would be grave, then a higher confi-
Current edition approved September 10, 1997. Published August 1998. Origi-
nally published as D4855–88. Last previous edition D4855–91.
dence level might be considered. If the consequences of
2
Annual Book of ASTM Standards, Vol 07.01.
incorrectly estimating the confidence interval are of less than
3
Annual Book of ASTM Standards, Vol 14.02.
4
1 usual concern, then a lower confidence interval might be
PC programs on floppy disks are available throughASTM. For a 3 ⁄2 inch disk
1
request PCN:12-429040-18, for a 5 ⁄4 inch disk request PCN:12-429041-18. considered.
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D4855–97 (2002)
3.1.5 confidence limits, n—the two statistics that define the 3.1.17 statistic, n—a quantity that is calculated from obser-
ends of a confidence interval. vations on a sample and that estimates a parameter of a sample
and that estimates a parameter of a population.
3.1.6 degrees of freedom, n—for a set,thenumberofvalues
that ca
...