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  • ASTM D 6708 : 2021

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

    Available format(s):  Hardcopy, PDF

    Language(s):  English

    Published date:  19-05-2021

    Publisher:  American Society for Testing and Materials

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    Scope - (Show below) - (Hide below)

    1.1This practice covers statistical methodology for assessing the expected agreement between two different standard test methods that purport to measure the same property of a material, and for the purpose of deciding if a simple linear bias correction can further improve the expected agreement. It is intended for use with results obtained from interlaboratory studies meeting the requirement of Practice D6300 or equivalent (for example, ISO 4259). The interlaboratory studies shall be conducted on at least ten materials in common that among them span the intersecting scopes of the test methods, and results shall be obtained from at least six laboratories using each method. Requirements in this practice shall be met in order for the assessment to be considered suitable for publication in either method, if such publication includes claim to have been carried out in compliance with this practice. Any such publication shall include mandatory information regarding certain details of the assessment outcome as specified in the Report section of this practice.

    1.2The 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 1:Failure to adhere to the parsimony principle generally results in models that are over-fitted and do not perform well in practice.

    1.3The bias corrections of this practice are limited to a constant correction, proportional correction, or a linear (proportional + constant) correction.

    1.4The 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.

    1.5A methodology is presented for establishing the numerical limit (designated by this practice as the between methods reproducibility) that would be exceeded about 5 % of the time (one case in 20 in the long run) 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, in the normal and correct operation of both test methods.

    Note 2:In earlier versions of this standard practice, the term “cross-method reproducibility” was used in place of the term “between methods reproducibility.” The change was made because the “between methods reproducibility” term is more intuitive and less confusing. It is important to note that these two terms are synonymous and interchangeable with one another, especially in cases where the “cross-method reproducibility” term was subsequently referenced by name in methods where a D6708 assessment was performed, before the change in terminology in this standard practice was adopted.

    Note 3:Users are cautioned against applying the between methods 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 6.7) 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 between methods reproducibility that adequately cover the range of sample-specific biases for different types of materials.

    1.6This practice is intended for test methods which measure quantitative (numerical) properties of petroleum or petroleum products.

    1.7The statistical calculations of this practice are also applicable for assessing the expected agreement between two different test methods that purport to measure the same property of a material using results that are not as described in 1.1, provided the results and associated statistics from each test method are obtained from a specifically designed multi-lab study or from a proficiency testing program (e.g.: ILCP) where for each sample a single result is provided by each lab for each test method. The comparison sample set shall comprise at least ten different materials that span the intersecting scopes of the test methods with no material exceeding the leverage requirement in Practice D6300. Results and statistics shall meet requirements in 1.7.1. Requirements in this practice shall be met in order for the assessment to be considered suitable for publication in either method, if such publication includes claim to have been carried out in compliance with this practice. Any such publication shall include mandatory information regarding certain details of the assessment as specified in the Report section of this practice. RXY shall be based on the published reproducibility of the methods.

    1.7.1For each test method and sample, results and statistics used to perform the assessment in 1.7 shall meet the following requirements:

    (1)No. of results (N) 10,

    (2)Anderson Darling statistic 1.12 (based on Normal Distribution),

    (3)Standard Error (sesample) is calculated using published reproducibility evaluated at the sample mean, N, and the factor 2.8 as follows:

    Equation D6708-21_1

    (4)sesample is numerically less than [Rpub / (2.8 √10 )], and

    (5)Sample standard deviation (ssample) per root-mean-square technique is not statistically greater than Rpub / 2.8 for at least 80 % of the samples in the comparison data set based on an F-test using 30 as the assumed degrees of freedom for Rpub, and (N − 1) for ssample at the 0.05 significance level.

    1.8The methodology in this practice can also be used to perform linear regression analysis between two variables (X, Y) where there is known uncertainty in both variables that may or may not be constant over the regression range. The common acronym used to describe this type of linear regression is ReXY (Regression with errors in X and Y). The ReXY technique for assessing the correlation between two variables as described in this practice can be used for investigative applications where the strict data input requirement may not be met, but the outcome can still be useful for the intended application. Use of this practice for ReXY should be conducted under the tutelage of subject matter experts familiar with the statistical theory and techniques described in this practice, the methodologies associated with the production and collection of the results to be used for the regression analysis, and interpretation of assessment outcome relative to the intended application.

    1.9This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

    General Product Information - (Show below) - (Hide below)

    Committee D 02
    Document Type Standard Practice
    Publisher American Society for Testing and Materials
    Status Current
    Supersedes

    Standards Referenced By This Book - (Show below) - (Hide below)

    ASTM D 2887 : 2019 : REV A : EDT 2 Standard Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography
    ASTM D 2983 : 2020 Standard Test Method for Low-Temperature Viscosity of Automatic Transmission Fluids, Hydraulic Fluids, and Lubricants using a Rotational Viscometer
    ASTM D 7825 : 2018 Standard Practice for Generating a Process Stream Property Value through Application of a Process Stream Analyzer
    ASTM D 7344 : 2017 : REV A Standard Test Method for Distillation of Petroleum Products and Liquid Fuels at Atmospheric Pressure (Mini Method)
    ASTM D 7668 : 2017 Standard Test Method for Determination of Derived Cetane Number (DCN) of Diesel Fuel Oils—Ignition Delay and Combustion Delay Using a Constant Volume Combustion Chamber Method
    ASTM D 6591 : 2019 Standard Test Method for Determination of Aromatic Hydrocarbon Types in Middle Distillates—High Performance Liquid Chromatography Method with Refractive Index Detection
    ASTM D 5001 : 2019 : EDT 1 Standard Test Method for Measurement of Lubricity of Aviation Turbine Fuels by the Ball-on-Cylinder Lubricity Evaluator (BOCLE)
    ASTM D 8183 : 2018 Standard Test Method for Determination of Indicated Cetane Number (ICN) of Diesel Fuel Oils using a Constant Volume Combustion Chamber—Reference Fuels Calibration Method
    ASTM D 8210 : 2020 Standard Test Method for Automatic Determination of Low-Temperature Viscosity of Automatic Transmission Fluids, Hydraulic Fluids, and Lubricants Using a Rotational Viscometer
    ASTM D 8071 : 2020 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)
    ASTM D 8150 : 2017 Standard Test Method for Determination of Organic Chloride Content in Crude Oil by Distillation Followed by Detection Using Combustion Ion Chromatography
    ASTM D 7945 : 2021 Standard Test Method for Determination of Dynamic Viscosity and Derived Kinematic Viscosity of Liquids by Constant Pressure Viscometer
    ASTM D 6122 : 2020 : REV A Standard Practice for Validation of the Performance of Multivariate Online, At-Line, Field and Laboratory Infrared Spectrophotometer, and Raman Spectrometer Based Analyzer Systems
    ASTM D 7235 : 2016 Standard Guide for Establishing a Linear Correlation Relationship Between Analyzer and Primary Test Method Results Using Relevant ASTM Standard Practices
    ASTM D 6839 : 2018 Standard Test Method for Hydrocarbon Types, Oxygenated Compounds, and Benzene in Spark Ignition Engine Fuels by Gas Chromatography
    ASTM D 6299 : 2020 : REV A Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
    ASTM D 8004 : 2015 Standard Test Method for Fuel Dilution of In-Service Lubricants Using Surface Acoustic Wave Sensing
    ASTM D 5950 : 2014 : R2020 Standard Test Method for Pour Point of Petroleum Products (Automatic Tilt Method)
    ASTM D 7923 : 2019 Standard Test Method for Water in Ethanol and Hydrocarbon Blends by Karl Fischer Titration
    ASTM D 4741 : 2021 Standard Test Method for Measuring Viscosity at High Temperature and High Shear Rate by Tapered-Plug Viscometer
    ASTM D 3828 : 2016 : REV A Standard Test Methods for Flash Point by Small Scale Closed Cup Tester
    ASTM D 5771 : 2021 Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Optical Detection Stepped Cooling Method)
    ASTM D 7808 : 2018 Standard Practice for Determining the Site Precision of a Process Stream Analyzer on Process Stream Material
    ASTM D 5481 : 2021 Standard Test Method for Measuring Apparent Viscosity at High-Temperature and High-Shear Rate by Multicell Capillary Viscometer
    ASTM D 7154 : 2015 Standard Test Method for Freezing Point of Aviation Fuels (Automatic Fiber Optical Method)
    ASTM D 7689 : 2021 Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Mini Method)
    ASTM D 5949 : 2016 Standard Test Method for Pour Point of Petroleum Products (Automatic Pressure Pulsing Method)
    ASTM D 7419 : 2018 Standard Test Method for Determination of Total Aromatics and Total Saturates in Lube Basestocks by High Performance Liquid Chromatography (HPLC) with Refractive Index Detection
    ASTM D 3606 : 2020 : EDT 1 Standard Test Method for Determination of Benzene and Toluene in Spark Ignition Fuels by Gas Chromatography
    ASTM D 7483 : 2021 Standard Test Method for Determination of Dynamic Viscosity and Derived Kinematic Viscosity of Liquids by Oscillating Piston Viscometer
    ASTM D 6756 : 2017 Standard Test Method for Determination of the Red Dye Concentration and Estimation of the ASTM Color of Diesel Fuel and Heating Oil Using a Portable Visible Spectrophotometer
    ASTM D 5188 : 2016 Standard Test Method for Vapor-Liquid Ratio Temperature Determination of Fuels (Evacuated Chamber and Piston Based Method)
    ASTM D 8340 : 2020 : REV A Standard Practice for Performance-Based Qualification of Spectroscopic Analyzer Systems
    ASTM D 1319 : 2020 : REV A Standard Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption
    ASTM D 5186 : 2020 Standard Test Method for Determination of the Aromatic Content and Polynuclear Aromatic Content of Diesel Fuels By Supercritical Fluid Chromatography
    ASTM D 6377 : 2020 Standard Test Method for Determination of Vapor Pressure of Crude Oil: VPCRx (Expansion Method)
    ASTM D 5580 : 2021 Standard Test Method for Determination of Benzene, Toluene, Ethylbenzene, p/m-Xylene, o-Xylene, C9 and Heavier Aromatics, and Total Aromatics in Finished Gasoline by Gas Chromatography
    ASTM D 7778 : 2015 Standard Guide for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
    ASTM D 7171 : 2020 Standard Test Method for Hydrogen Content of Middle Distillate Petroleum Products by Low-Resolution Pulsed Nuclear Magnetic Resonance Spectroscopy
    ASTM D 4683 : 2020 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
    ASTM D 6550 : 2020 Standard Test Method for Determination of Olefin Content of Gasolines by Supercritical-Fluid Chromatography
    ASTM D 7345 : 2017 Standard Test Method for Distillation of Petroleum Products and Liquid Fuels at Atmospheric Pressure (Micro Distillation Method)
    ASTM D 7279 : 2020 Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids by Automated Houillon Viscometer
    ASTM D 409/D409M : 2016 Standard Test Method for Grindability of Coal by the Hardgrove-Machine Method
    ASTM D 7215 : 2016 Standard Test Method for Calculated Flash Point from Simulated Distillation Analysis of Distillate Fuels
    ASTM D 4929 : 2019 : REV A Standard Test Method for Determination of Organic Chloride Content in Crude Oil
    ASTM D 4815 : 2015 : REV B : R2019 Standard Test Method for Determination of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C1 to C4 Alcohols in Gasoline by Gas Chromatography
    ASTM D 6300 : 2021 Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
    ASTM D 7094 : 2017 : REV A Standard Test Method for Flash Point by Modified Continuously Closed Cup (MCCCFP) Tester
    ASTM D 86 : 2020 : REV B Standard Test Method for Distillation of Petroleum Products and Liquid Fuels at Atmospheric Pressure
    ASTM D 6792 : 2020 Standard Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
    ASTM D 6890 : 2018 Standard Test Method for Determination of Ignition Delay and Derived Cetane Number (DCN) of Diesel Fuel Oils by Combustion in a Constant Volume Chamber
    ASTM D 6378 : 2020 Standard Test Method for Determination of Vapor Pressure (VPX) of Petroleum Products, Hydrocarbons, and Hydrocarbon-Oxygenate Mixtures (Triple Expansion Method)
    ASTM D 445 : 2019 : REV A Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
    ASTM D 7798 : 2020 Standard Test Method for Boiling Range Distribution of Petroleum Distillates with Final Boiling Points up to 538 °C by Ultra Fast Gas Chromatography (UF GC)
    ASTM D 7346 : 2015 : R2021 Standard Test Method for No Flow Point and Pour Point of Petroleum Products and Liquid Fuels
    ASTM D 2068 : 2020 Standard Test Method for Determining Filter Blocking Tendency
    ASTM D 7795 : 2015 Standard Test Method for Acidity in Ethanol and Ethanol Blends by Titration
    ASTM D 5769 : 2020 Standard Test Method for Determination of Benzene, Toluene, and Total Aromatics in Finished Gasolines by Gas Chromatography/Mass Spectrometry
    ASTM D 8092 : 2017 Standard Test Method for Field Determination of Kinematic Viscosity Using a Microchannel Viscometer
    ASTM D 7042 : 2021 Standard Test Method for Dynamic Viscosity and Density of Liquids by Stabinger Viscometer (and the Calculation of Kinematic Viscosity)

    Standards Referencing This Book - (Show below) - (Hide below)

    ASTM D 6299 : 2021 Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
    ASTM D 6299 : 2022 : EDT 1 Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
    ASTM D 5769 : 2022 Standard Test Method for Determination of Benzene, Toluene, and Total Aromatics in Finished Gasolines by Gas Chromatography/Mass Spectrometry
    ASTM D 6299 : 2022 Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
    ASTM D 6299 : 2020 : REV A Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
    ASTM D 7372 : 2017 Standard Guide for Analysis and Interpretation of Proficiency Test Program Results
    ASTM D 7372 : 2021 Standard Guide for Analysis and Interpretation of Proficiency Test Program Results
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