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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.

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.