ASTM D6708-01e1

Standard Practice for Statistical Assessment and Improvement of the Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material

SCOPE
1.1 This practice defines statistical methodology for assessing the expected agreement between two standard test methods that purport to measure the same property of a material, and deciding if a simple linear bias correction can further improve the expected agreement. It is intended for use with results collected from an interlaboratory study meeting the requirement of Practice D 6300 or equivalent (for example, ISO 4259). The interlaboratory study must be conducted on at least ten materials that span the intersecting scopes of the test methods, and results must be obtained from at least six laboratories using each method.
Note 1--Examples of standard test methods are those developed by voluntary consensus standards bodies such as ASTM, IP/BSI, DIN, AFNOR, CGSB.
1.2 The statistical methodology is based on the premise that a bias correction will not be needed. In the absence of strong statistical evidence that a bias correction would result in better agreement between the two methods, a bias correction is not made. If a bias correction is required, then the parsimony principle is followed whereby a simple correction is to be favored over a more complex one.
Note 2--Failure to adhere to the parsimony principle generally results in models that are over-fitted and do not perform well in practice.
1.3 The bias corrections of this practice are limited to a constant correction, proportional correction or a linear (proportional + constant) correction.
1.4 The bias-correction methods of this practice are method symmetric, in the sense that equivalent corrections are obtained regardless of which method is bias-corrected to match the other.
1.5 A methodology is presented for establishing the 95 % confidence limit (designated by this practice as the  cross-method reproducibility) for the difference between two results where each result is obtained by a different operator using different apparatus and each applying one of the two methods X and Y on identical material, where one of the methods has been appropriately bias-corrected in accordance with this practice.Note 3--Users are cautioned against applying the cross-method reproducibility as calculated from this practice to materials that are significantly different in composition from those actually studied, as the ability of this practice to detect and address sample-specific biases (see 6.8) is dependent on the materials selected for the interlaboratory study. When sample-specific biases are present, the types and ranges of samples may need to be expanded significantly from the minimum of ten as specified in this practice in order to obtain a more comprehensive and reliable 95 % confidence limits for cross method reproducibility that adequately cover the range of sample specific biases for different types of materials.
1.6 This practice is intended for test methods which measure quantitative (numerical) properties of petroleum or petroleum products.

General Information

• Status: Historical
• Publication Date: 09-Aug-2001
• ICS: 75.080 - Petroleum products in general
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.94 - Coordinating Subcommittee on Quality Assurance and Statistics

Relations

• Replaces: ASTM D6708-01 - Standard Practice for Statistical Assessment and Improvement of the Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 10-Aug-2001
• Replaced By: ASTM D6708-04 - Standard Practice for Statistical Assessment and Improvement of the Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-May-2004
• Referred By: ASTM D6300-23 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 10-Aug-2001
• Referred By: ASTM D6299-23e1 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 10-Aug-2001
• Referred By: ASTM D8210-22 - Standard Test Method for Automatic Determination of Low-Temperature Viscosity of Automatic Transmission Fluids, Hydraulic Fluids, and Lubricants Using a Rotational Viscometer
• Effective Date: 10-Aug-2001
• Referred By: ASTM D1319-20a - Standard Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption
• Effective Date: 10-Aug-2001
• Referred By: ASTM D3828-16a(2021) - Standard Test Methods for Flash Point by Small Scale Closed Cup Tester
• Effective Date: 10-Aug-2001
• Referred By: ASTM D7808-22 - Standard Practice for Determining the Site Precision of a Process Stream Analyzer on Process Stream Material
• Effective Date: 10-Aug-2001
• Referred By: ASTM D4741-21 - Standard Test Method for Measuring Viscosity at High Temperature and High Shear Rate by Tapered-Plug Viscometer
• Effective Date: 10-Aug-2001
• Referred By: ASTM D8071-21 - Standard Test Method for Determination of Hydrocarbon Group Types and Select Hydrocarbon and Oxygenate Compounds in Automotive Spark-Ignition Engine Fuel Using Gas Chromatography with Vacuum Ultraviolet Absorption Spectroscopy Detection (GC-VUV)
• Effective Date: 10-Aug-2001
• Referred By: ASTM D4683-20 - Standard Test Method for Measuring Viscosity of New and Used Engine Oils at High Shear Rate and High Temperature by Tapered Bearing Simulator Viscometer at 150 °C
• Effective Date: 10-Aug-2001
• Referred By: ASTM D7419-18 - Standard Test Method for Determination of Total Aromatics and Total Saturates in Lube Basestocks by High Performance Liquid Chromatography (HPLC) with Refractive Index Detection
• Effective Date: 10-Aug-2001
• Referred By: ASTM D5771-21 - Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Optical Detection Stepped Cooling Method)
• Effective Date: 10-Aug-2001
• Referred By: ASTM D8340-22 - Standard Practice for Performance-Based Qualification of Spectroscopic Analyzer Systems
• Effective Date: 10-Aug-2001
• Referred By: ASTM D409/D409M-16 - Standard Test Method for Grindability of Coal by the Hardgrove-Machine Method
• Effective Date: 10-Aug-2001

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
An American National Standard
e1
Designation: D 6708 – 01
Standard Practice for
Statistical Assessment and Improvement of the Expected
Agreement Between Two Test Methods that Purport to
1
Measure the Same Property of a Material
This standard is issued under the fixed designation D6708; 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
e NOTE—Corrected Eq 8 editorially in November 2003.
1. Scope where each result is obtained by a different operator using
different apparatus and each applying one of the two methods
1.1 This practice defines statistical methodology for assess-
X and Y on identical material, where one of the methods has
ingtheexpectedagreementbetweentwostandardtestmethods
been appropriately bias-corrected in accordance with this
that purport to measure the same property of a material, and
practice.
deciding if a simple linear bias correction can further improve
the expected agreement. It is intended for use with results
NOTE 3—Users are cautioned against applying the cross-method repro-
collected from an interlaboratory study meeting the require- ducibilityascalculatedfromthispracticetomaterialsthataresignificantly
different in composition from those actually studied, as the ability of this
ment of Practice D 6300 or equivalent (for example,
practicetodetectandaddresssample-specificbiases(see6.8)isdependent
ISO4259). The interlaboratory study must be conducted on at
on the materials selected for the interlaboratory study. When sample-
least ten materials that span the intersecting scopes of the test
specific biases are present, the types and ranges of samples may need to
methods, and results must be obtained from at least six
be expanded significantly from the minimum of ten as specified in this
laboratories using each method.
practice in order to obtain a more comprehensive and reliable 95%
confidence limits for cross method reproducibility that adequately cover
NOTE 1—Examples of standard test methods are those developed by
the range of sample specific biases for different types of materials.
voluntary consensus standards bodies such as ASTM, IP/BSI, DIN,
AFNOR, CGSB.
1.6 This practice is intended for test methods which mea-
sure quantitative (numerical) properties of petroleum or petro-
1.2 The statistical methodology is based on the premise that
leum products.
a bias correction will not be needed. In the absence of strong
statistical evidence that a bias correction would result in better
2. Referenced Documents
agreement between the two methods, a bias correction is not
2.1 ASTM Standards:
made. If a bias correction is required, then the parsimony
D5580 Test Method for Determination of Benzene, Tolu-
principle is followed whereby a simple correction is to be
ene, Ethylbenzene plm-Xylene, o-Xylene, C and Heavier
favored over a more complex one. 9
Aromatics and Total Aromatics in Finished Gasoline by
NOTE 2—Failure to adhere to the parsimony principle generally results 2
Gas Chromatography
in models that are over-fitted and do not perform well in practice.
D5769 Test Method for Determination of Benzene, Tolu-
1.3 The bias corrections of this practice are limited to a
ene, and Total Aromatics in Finished Gasoline by Gas
2
constantcorrection,proportionalcorrectionoralinear(propor-
Chromatography/Mass Spectrometry
tional + constant) correction.
D6299 Practice for Applying Statistical Quality Assurance
1.4 The bias-correction methods of this practice are method
Techniques to Evaluate Analytical Measurement System
2
symmetric,inthesensethatequivalentcorrectionsareobtained
Performance
regardless of which method is bias-corrected to match the
D6300 Practice for Determination of Precision and Bias
other.
Data for Use in Test Methods for Petroleum Products and
2
1.5 A methodology is presented for establishing the 95%
Lubricants
3
confidence limit (designated by this practice as the cross-
2.2 ISO Standard
method reproducibility) for the difference between two results
ISO 4259 Petroleum Products—Determination and applica-
tion of precision data in relation to methods of test.
1
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
2
ProductsandLubricantsandisthedirectresponsibilityofSubcommitteeD02.94on Annual Book of ASTM Standards, Vol 05.03.
3
Quality Assurance and Statistics. Available from American National Standards Institute, 11 W. 42nd St., 13th
Current edition approved Aug. 10, 2001. Published October 2001. floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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