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1.1 This practice presents guidelines for preparing clear and meaningful precision statements for test method standards on tires and related objects pertinent to the tire industry and within the scope of ASTM Committee F-9. It gives definitions, explains the potential use of precision for standard test methods and gives the requirements for interlaboratory or inter-test-site programs. The calculation algorithms for determining precision and the format for expressing precision are also given.

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4.1 Part A of the “Blue Book,” Form and Style for ASTM Standards, requires that all test methods include statements of precision and bias. This practice discusses these two concepts and provides guidance for their use in statements about test methods.4.2 Precision—A statement of precision allows potential users of a test method to assess in general terms the test method’s usefulness with respect to variability in proposed applications. A statement of precision is not intended to exhibit values that can be exactly duplicated in every user’s laboratory. Instead, the statement provides guidelines as to the magnitude of variability that can be expected between test results when the method is used in one, or in two or more, reasonably competent laboratories. For a discussion of precision, see 8.1.4.3 Bias—A statement of bias furnishes guidelines on the relationship between a set of typical test results produced by the test method under specific test conditions and a related set of accepted reference values (see 9.1).4.3.1 An alternative term for bias is trueness, which has a positive connotation, in that greater bias is associated with less favorable trueness. Trueness is the systematic component of accuracy.4.4 Accuracy—The term “accuracy,” used in earlier editions of Practice E177, embraces both precision and bias (see 9.3).AbstractThe purpose of this practice is to present concepts necessary to the understanding of the terms “precision” and “bias” as used in quantitative test methods. This practice also describes methods of expressing precision and bias and, in a final section, gives examples of how statements on precision and bias may be written for ASTM test methods. A statement of precision allows potential users of a test method to assess in general terms the test method’s usefulness with respect to variability in proposed applications.1.1 The purpose of this practice is to present concepts necessary to the understanding of the terms “precision” and “bias” as used in quantitative test methods. This practice also describes methods of expressing precision and bias and, in a final section, gives examples of how statements on precision and bias may be written for ASTM test methods.1.2 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.3 This 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.

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4.1 Both suppliers and users of pulverized ceramic powders will find this test method useful to determine particle size distributions for materials specifications, manufacturing control, development, and research.4.2 The test method is simple, although tedious, uses inexpensive equipment, and will provide a continuous curve with data obtained with standardized woven sieves.1.1 This guide covers the determination of the particle size distribution of pulverized alumina and quartz for particle sizes from 45 to 5 μm by wet sieving.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.2.1 The only exception is in the Section 5, Apparatus, 5.1 where there is no relevant SI equivalent.1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This 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.

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定价： 590元 / 折扣价： 502 元 加购物车

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4.1 Precision statements for calculated values can be developed using this approach. Users can also evaluate how an individual test method’s precision influences the variability of calculated values.4.2 The standard deviation of a calculated value that is the sum, difference, product, or quotient of two or more test method results, each with their own precision statement, can be calculated so long as the individual variables (that is, test results) are independent and the standard deviations are small relative to their mean values. These restrictions are usually met in ASTM methods. In those cases where these restrictions are not met, other methods can be used. Only cases complying with the restrictions are covered in this standard.1.1 Material and mixture properties such as air voids and voids in mineral aggregates (VMA) are calculated from two or three test results, combined in simple mathematical relationships. The standard deviation equations for these calculated values can be developed using a mathematical process called “propagation of errors” (also called “propagation of uncertainty”). This practice includes uncertainty equations for four forms or material and mixture equations: when two test results are (1) added or subtracted, (2) multiplied together, (3) one divided by the other, and (4) two test results divided by a third.1.2 This approach to calculating standard deviation equations is only valid when the distributions of the test results from the two standards are independent (that is, not correlated).1.3 The accuracy of a calculated standard deviation is dependent on the accuracy of the standard deviations used for the individual test result methods.1.4 Values for the mean and standard deviation for each test method are needed to determine the standard deviation for a calculated value.1.5 Examples of how to use these equations are shown in Appendix X1.1.6 A brief explanation of how standard deviation equations are derived for more complicated material and mixture equations is also included.1.7 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.1.8 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.9 This 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.

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5.1 ASTM test methods are frequently intended for use in the manufacture, selling, and buying of materials in accordance with specifications and therefore should provide such precision that when the test is properly performed by a competent operator, the results will be found satisfactory for judging the compliance of the material with the specification. Statements addressing precision and bias are required in ASTM test methods. These then give the user an idea of the precision of the resulting data and its relationship to an accepted reference material or source (if available). Statements addressing determinability are sometimes required as part of the test method procedure in order to provide early warning of a significant degradation of testing quality while processing any series of samples.5.2 Repeatability and reproducibility are defined in the precision section of every Committee D02 test method. Determinability is defined above in Section 3. The relationship among the three measures of precision can be tabulated in terms of their different sources of variation (see Table 1).5.2.1 When used, determinability is a mandatory part of the Procedure section. It will allow operators to check their technique for the sequence of operations specified. It also ensures that a result based on the set of determined values is not subject to excessive variability from that source.5.3 A bias statement furnishes guidelines on the relationship between a set of test results and a related set of accepted reference values. When the bias of a test method is known, a compensating adjustment can be incorporated in the test method.5.4 This practice is intended for use by D02 subcommittees in determining precision estimates and bias statements to be used in D02 test methods. Its procedures correspond with ISO 4259 and are the basis for the Committee D02 computer software, Calculation of Precision Data: Petroleum Test Methods. The use of this practice replaces that of Research Report RR:D02-1007.25.5 Standard practices for the calculation of precision have been written by many committees with emphasis on their particular product area. One developed by Committee E11 on Statistics is Practice E691. Practice E691 and this practice differ as outlined in Table 2.1.1 This practice covers the necessary preparations and planning for the conduct of interlaboratory programs for the development of estimates of precision (determinability, repeatability, and reproducibility) and of bias (absolute and relative), and further presents the standard phraseology for incorporating such information into standard test methods.1.2 This practice is generally limited to homogeneous petroleum products, liquid fuels, and lubricants with which serious sampling problems (such as heterogeneity or instability) do not normally arise.1.3 This practice may not be suitable for products with sampling problems as described in 1.2, solid or semisolid products such as petroleum coke, industrial pitches, paraffin waxes, greases, or solid lubricants when the heterogeneous properties of the substances create sampling problems. In such instances, consult a trained statistician.1.4 This 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.

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This practice provides guidance in preparing precision and bias statements for ASTM test methods pertaining to construction materials. Test method shall conform to the maximum acceptable range of individual measurements. In order to be valid the indexes of precision to be included in the precision statement as guides for the operator must be based on estimates of the precision of the test method obtained from a statistically designed inter-laboratory series of tests. This series of tests must involve a sufficient number of laboratories, materials, and replicate measurements so that the results obtained provide reliable estimates of the true precision characteristic of the test method. The procedures described in this practice are based on the assumption that the proper estimates of precision have already been obtained. In any test method, tolerances are placed on the accuracy of measuring equipment. All tests made with a given set of equipment which has an error within the permitted tolerance will produce results with a small consistent bias, but that bias is not inherent in the test method and is not included in the bias statement for the test method. There are two conditions which permit the bias of a test method to be estimated: a standard reference sample of known value has been tested by the test method, and the test method has been applied to a sample which has been compounded in such a manner that the true value of the property being measured is known, such as may be the case, for example, in a test for cement content of concrete.1.1 The Form and Style for ASTM Standards requires that all test methods contain statements on precision and bias. Further, the precision statement is required to contain a statement on single-operator precision (repeatability) and a statement on multilaboratory precision (reproducibility). This practice provides guidance for preparing precision and bias statements that comply with these requirements. Discussion of the purpose and significance of precision and bias statements for users of test methods is also provided. Examples of precision statements that conform to this practice are included in Appendix X1. This practice supplements Practice E177 and has been developed to meet the needs of ASTM Committees dealing with construction materials.NOTE 1: Although this practice is under the jurisdiction of Committee C09, the current version was developed jointly by Committees C01 and C09 and has subsequently been adopted for use by other committees dealing with construction materials.1.2 This practice assumes that an interlaboratory study (ILS) has been completed in accordance with Practice C802 or Practice E691. The interlaboratory study provides the necessary statistical values to write the precision and bias statements.1.3 The system of units for this practice is not specified. Dimensional quantities in the practice are presented only in examples of precision and bias statements.1.4 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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4.1 Tests are conducted using standard test methods to generate test data that are used to make decisions for commercial, technical, and scientific purposes. It follows that the precision of a particular test method is an important quality characteristic or figure of merit for a test method and a decision process.4.2 An evaluation of the precision of a test method is normally conducted with (1) some selected group of materials as typically used with that method and (2) with a group of volunteer laboratories that have experience with the test method. The evaluation represents an event in time for the test method for these materials and laboratories. Another ITP precision evaluation with somewhat different materials or even with the same materials with the same laboratories at a different time, may generate precision results that differ from the initial ITP.4.3 Experience as indicated in Refs (1-4)4 and elsewhere has shown that the poor reproducibility among the laboratories of a typical ITP is almost always due to interlaboratory bias. Certain laboratories are always low or high compared to a reference as well as other laboratories in all tests. This usual outcome for many ITPs is addressed in this practice by the use of the three-step robust analysis procedures as described in Section 7.4.4 Caution is urged in applying precision results of a particular test method to product testing for consumer-producer product acceptance. Product acceptance procedures should be developed on the basis of precision data obtained in special programs that are specific to the commercial products and to the laboratories of the interested parties for this type of testing.1.1 This practice covers guidelines for evaluating precision and serves as the governing practice for interlaboratory test programs (ITP) used to evaluate precision for test methods as used in the rubber manufacturing and the carbon black industries. This practice uses the basic one way analysis of variance calculation algorithms of Practice E691. Although bias is not evaluated in this practice, it is an essential concept in understanding precision evaluation.1.2 This practice applies to test methods that have test results expressed in terms of a quantitative continuous variable. Although exceptions may occur, it is in general limited to test methods that are fully developed and in routine use in a number of laboratories.1.3 Two precision evaluation methods are given that are described as robust statistical procedures that attempt to eliminate or substantially decrease the influence of outliers. The first is a General Precision procedure intended for all test methods in the rubber manufacturing industry, and the second is a specific variation of the general precision procedure designated as Special Precision, that applies to carbon black testing. Both of these procedures use the same uniform level experimental design and the Mandel h and k statistics to review the precision database for potential outliers. However, they use slight modifications in the procedure for rejecting incompatible data values as outliers. The Special Precision procedure is specific as to the number of replicates per database cell or material-laboratory combination.1.4 This practice is divided into the following sections:  Section  1Referenced Documents  2Terminology  3  4Precision Evaluation—General Precision and Special Precision  5Steps in Organizing an Interlaboratory Test Program (ITP)  6Overview of the General Precision Analysis Procedure  7General Precision: Analysis Step 1  8 Preliminary Graphical Data Review  8.1 Calculation of Precision for Original Database  8.2 Detection of Outliers at 5 % Significance Level Using h and k Statistics  8.3 Generation of Revision 1 Database Using Outlier Treatment Option 1 or 2  8.4General Precision: Analysis Step 2  9 Calculation of Precision for Revision 1 Database  9.1 Detection of Outliers at 2 % Significance Level Using h and k Statistics  9.1 Generation of Revision 2 Database Using Outlier Treatment Option 1 or 2  9.1.2General Precision: Analysis Step 3  10 Calculation of Precision Using Revision 2 Database  10.1Special Precision Analysis—Carbon Black Testing  11Format for Precision Table and Clause in Test Method Standards  12Preparation of Report for Precision Analysis  13Definitions for Selected Terms Concerned with Precision and Testing Annex A1Statistical Model for Interlaboratory Testing Programs Annex A2Calculating the h and k Consistency Statistics for Outliers Annex A3Spreadsheet Calculation Formulas, Table Layout, and Calculation Sequence Annex A4Procedure for Calculating Replacement Values of Deleted Outliers Annex A5Example of General Precision Evaluation—Mooney Viscosity Testing Annex A61.5 Six annexes are presented; these serve as supplements to the main body of this practice. Annex A1 and Annex A2 are given mainly as background information that is important for a full understanding of precision evaluation. Annex A3 – Annex A5 contain detailed instructions and procedures needed to perform the operations as called for in various parts of the practice. The use of these annexes in this capacity avoids long sections of involved instruction in the main body of this practice. This allows for a better presentation and understanding of the central concepts involved in the evaluation of precision. Annex A6 is also important; it gives a complete example of precision evaluation that illustrates all of the procedures and options likely to be encountered in any precision evaluation, from the simple to the most complex.1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This 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.

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5.1 ASTM regulations require precision statements in all test methods in terms of repeatability and reproducibility. This practice is used when the number of participating laboratories or materials being tested, or both, in a precision study is less than the number specified by Practice E691. When possible, it is strongly recommended that a full Practice E691 standard protocol be followed to determine test method precision. Precision results produced by the procedures presented in this standard will not have the same degree of accuracy as results generated by a full Practice E691 protocol. This procedure will allow for the development of useful precision results when a full complement of laboratories is not available for interlaboratory testing.5.2 This practice is based on recommendations for interlaboratory studies and data analysis presented in Practice E691. This practice does not concern itself with the development of test methods but with a standard means for gathering information and treating the data needed for developing a precision statement for a test method when a complete Practice E691 interlaboratory study and data analysis are not possible.1.1 This practice describes the techniques for planning, conducting, analyzing, and treating results of an interlaboratory study (ILS) for estimating the precision of a test method when fewer than six laboratories are available to meet the recommended minimum requirements of Practice E691. Data obtained from an interlaboratory study are useful in identifying variables that require modifications for improving test method performance and precision.1.2 Precision estimates developed using this practice will not be statistically equivalent to precision estimates produced by Practice E691 because a small number of laboratories are used. The smaller number of participating laboratories will seriously reduce the value of precision estimates reported by this practice. However, under circumstances where only a limited number of laboratories are available to participate in an ILS, precision estimates developed by this practice will provide the user with useful information concerning precision for a test method.1.3 A minimum of three qualified laboratories is required for conducting an ILS using this practice. If six or more laboratories are available to participate in an ILS for a given test method, Practice E691 shall be used for conducting the ILS.1.4 Since the primary purpose of this practice is the development of the information needed for a precision statement, the experimental design in this practice will not be optimum for evaluating all materials, test methods, or as a tool for individual laboratory analysis.1.5 Because of the reduced number of participating laboratories, a Laboratory Monitor shall be used in the ILS. See Guide E2335.1.6 Field of Application—This practice is concerned with test methods that yield numerical values or a series of numerical values for different properties associated with the test method. The numerical values mentioned above are typically the result of calculations from a set of measurements.1.7 This practice includes design information suitable for use with the development of interlaboratory studies for test methods that have categorization (go-no-go) allocation test results. However, it does not provide a recommended statistical practice for evaluating the go-no-go data.1.8 This practice cannot be used to provide quantitative measures.1.9 This practice is issued under Committee E05, but it is generic in its statistical approach such that it is applicable to any other method.1.10 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.11 This 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.

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