5.1 ASTM regulations require precision statements for all test methods in terms of repeatability and reproducibility. This practice may be used in obtaining the information needed to prepare a precision statement in accordance with Practice E177 and the “Blue Book.”

1.1 This practice describes the techniques for planning, conducting, and analyzing the results of an interlaboratory study (ILS) conducted for certain test methods within Committee E12.

1.2 This practice does not concern itself with the development of the test method but rather with the gathering of the information needed for the precision and bias statement after the completion of development of the test method. The data obtained in the ILS may indicate, however, that further effort is needed to improve the test method.

1.3 This practice is concerned exclusively with test methods that derive a multi-valued measurand, such as, but not limited to, spectral reflectance, transmittance function, tristimulus values, or RGB values. Variation in measurements of such multi-valued measurands are usually analyzed by reducing the data to a single-valued parameter, such as color difference, ΔE.

1.4 This practice covers methods of dealing with the non-normal distribution of the variation of sets of color-differences. This is done so that the user may derive valid statistics from such non-normal distributions.

1.5 This practice does not cover test methods, even in Committee E12, whose measurands are single-valued, or whose variations are known to be normally distributed. Task groups involved with such test methods are referred to Practice E691 which contains preferable methods of analyzing data with those properties.

1.6 This practice is not intended to establish a method for estimating possible color-difference tolerances.

1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

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.