ASTM D4697-95(2001)
(Guide)Standard Guide for Maintaining Test Methods in the User's Laboratory (Withdrawn 2009)
Standard Guide for Maintaining Test Methods in the User's Laboratory (Withdrawn 2009)
SIGNIFICANCE AND USE
Following this guide will aid the user in maintaining control of both the bias and the precision of any test method.
4.1.1 It is necessary to control bias so that, if a change in level of an unknown material under test occurs, the user can be confident that the change was not due to the execution of the test method.
4.1.2 It is also necessary to control precision so that the established confidence limits and critical differences will be maintained.
Should the use of the test method be out of control, this guide will detect it, and may give an indication of where the problem lies.
SCOPE
1.1 This guide is intended to assist laboratories in maintaining precision and controlling bias in testing. It includes statistical procedures for detecting lack of control, changes in calibration constants, and in operator technique. Suggestions are given for the correction of some out of control situations.
1.2 This guide includes the following topics: Topic Title SectionNumberScope1Referenced Documents2Terminology3Significance and Use4Calibration Control5Test Performance Control6
Annexes:
Calibration ControlAnnex A1Test Performance ControlAnnex A2
1.3 This standard does not give all of the details for preparing statistical quality control charts or the statistical tests used to interpret them, but such information may be found easily in a number of publications.
WITHDRAWN RATIONALE
This guide is intended to assist laboratories in maintaining precision and controlling bias in testing.
Formerly under the jurisdiction of Committee D13 on Textiles, , this guide was withdrawn in March 2009 because D13 no longer has the expertise to maintain and statistical standards are being maintained by committee E11.
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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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D4697–95 (Reapproved 2001)
Standard Guide for
Maintaining Test Methods in the User’s Laboratory
This standard is issued under the fixed designation D 4697; 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 (e) indicates an editorial change since the last revision or reapproval.
throughASTM Headquarters, 100 Barr Harbor Drive, Conshohocken, PA
1. Scope
19428,USA.Thecontrolchartparametersdescribedintheannexesofthis
1.1 This guide is intended to assist laboratories in maintain-
guide can be calculated with one of these programs and the control charts
ing precision and controlling bias in testing. It includes
screen plotted.
statistical procedures for detecting lack of control, changes in
3. Terminology
calibration constants, and in operator technique. Suggestions
are given for the correction of some out of control situations.
3.1 Definitions:
1.2 This guide includes the following topics:
3.1.1 accuracy, n—of a test method, the degree of agree-
Section
ment between the true value of the property being tested (or an
Topic Title Number
accepted standard value) and the average of many observations
Scope 1
made according to the test method, preferably by many
Referenced Documents 2
Terminology 3
observers. (See also bias and precision.)
Significance and Use 4
3.1.2 attribute data, n—observed values or determinations
Calibration Control 5
which indicate the presence or absence of specific character-
Test Performance Control 6
istics.
Annexes:
3.1.3 bias, n—in statistics, a constant or systematic error in
test results.
Calibration Control Annex A1
Test Performance Control Annex A2
3.1.3.1 Discussion—Bias can exist between the true value
andatestresultobtainedfromonemethod;betweentestresults
1.3 This standard does not give all of the details for
from two methods; or between two test results obtained from a
preparing statistical quality control charts or the statistical tests
single method, for example, between operators or between
used to interpret them, but such information may be found
laboratories.
easily in a number of publications.
3.1.4 calibrate, vt—to determine and record the relationship
2. Referenced Documents
between a set of standard units of measure and the output of an
instrument or test procedure.
2.1 ASTM Standards:
3.1.5 calibration, n—the act or process of calibrating; the
D 123 Terminology Relating to Textiles
recorded relationship resulting from calibrating.
D 1578 Test Method for Breaking Strength ofYarn in Skein
3.1.6 measurement value, n—the numerical result of quan-
Form
tifying a particular property or dimension. (Syn. measurement,
E 456 Terminology Relating to Quality and Statistics
measurement datum.)
2.2 ASTM Adjuncts:
3.1.7 moving range, MR, n—the difference without regard
TEX-PAC
to sign between two successive observations.
NOTE 1—Tex-Pac is a group of PC programs on floppy disks, available
3.1.8 precision, n—the degree of agreement within a set of
observations or test results obtained as directed in a test
This guide is under the jurisdiction of ASTM Committee D13 on Textiles and
method.
is the direct responsibility of Subcommittee D13.93 on Statistics.
3.1.8.1 Discussion—The term “precision” delimited in vari-
Current edition approved May 15, 1995. Published July 1995. Originally
ouswaysisusedtodescribedifferentaspectsofprecision.This
published as D 4697 – 87. Last previous edition D 4697 – 91.
usage was chosen in preference to the use of “repeatability”
For information see: Juran, J. M., ed., Quality Control Handbook, McGraw
Hill, New York, 4th ed., 1988; Manual on Presentation of Data and Control Chart
and “reproducibility” which have been assigned conflicting
Analysis, ASTM STP 15D,ASTM, 1976; and Statistical Quality Control Handbook,
meanings by various authors and standardizing bodies.
Western Electric Co., Inc., 2nd ed., 1985 (Inquiries may be made to: AT& T
3.1.9 test method, n—a definitive procedure for the identi-
Technologies, Commercial Sales Clerk, Select Code 700-444, P.O. Box 19901,
Indianapolis, IN 44219). fication, measurement, and evaluation of one or more qualities,
Annual Book of ASTM Standards, Vol 07.01.
characteristics, or properties of a material, product, system, or
Annual Book of ASTM Standards, Vol 14.02.
service that produces a test result.
PC programs on floppy disks are available throughASTM. For a 3 ⁄2 inch disk
1 3.1.10 verification, n—the act or process of verifying.
request PCN:12-429040-18, for a 5 ⁄4 inch disk request PCN:12-429041-18.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4697
3.1.11 verify, vt—(1) to determine whether a previously 5.3.2 In the case of calibration control, it is seldom neces-
calibrated instrument, standard solution, or other standard is sary to plot a control chart for the range of specimens. This
still properly calibrated; (2) to establish that an operation has aspect of test method maintenance will usually be well
been completed correctly. controlledwhenthedirectionsin6.1,6.2,and6.5arefollowed.
3.1.12 For definitions of textile terms in this standard, refer
to Terminology D 123. For definitions of statistical terms in 6. Test Performance Control
this standard, refer to Terminology D 123 or Terminology
6.1 Standard Sample—Reserve an adequate supply of a
E 456.
stable standard sample of material for maintaining test perfor-
3.2 Definitions of Terms Specific to This Standard:
mance (Note 2). Each day, before making a test on unknown
3.2.1 maintain—to monitor the usage of test methods and to
laboratory samples, have each analyst run an analysis on the
take remedial steps when necessary.
standard sample. Have the analyst use the machine he will use
later to test the unknown samples.
4. Significance and Use
4.1 Following this guide will aid the user in maintaining NOTE 2—It is essential to obtain a new supply of a standard material
well before the old supply is exhausted, and to run the old supply and the
control of both the bias and the precision of any test method.
new supply in parallel for a short length of time.
4.1.1 It is necessary to control bias so that, if a change in
level of an unknown material under test occurs, the user can be
6.1.1 If a supply of a stable standard sample cannot be
confident that the change was not due to the execution of the
obtained, there are techniques available for overcoming this
test method.
problem. For example, two analysts could analyze a specimen
4.1.2 It is also necessary to control precision so that the
from the same sample at the same time, and the difference
established confidence limits and critical differences will be
between the two results could be plotted. For problems of this
maintained.
kind, competent statistical help is required in the planning of
4.2 Should the use of the test method be out of control, this
the program, the presentation, and analysis of the data.
guide will detect it, and may give an indication of where the
6.2 Quality Control Chart—Using the standard sample test
problem lies.
data, establish statistical quality control charts for the test
results produced by each analyst-instrument pair. If there is
5. Calibration Control
more than one analyst-instrument pair, plot a separate average
5.1 Calibration Procedure—To be completely useful, the
and range chart for each pair, using the same control lines (for
test method must contain a calibration procedure if it makes
an example, see Annex A2).
useofareagent,apparatus,orstandardthatissubjecttochange
6.3 Average Center Line—Use the established expected test
withageoruse.Ifitdoesnothaveacalibrationprocedure,then
value of the standard sample as the center line on the chart for
one should be obtained or written and incorporated in the
averages. This value may have been obtained with a standard
method.
material procured from an ou
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