Standard Addresses Precision Issues for Color
ASTM International Committee E12 on Color and Appearance has approved a new standard that describes techniques for planning and analyzing the results of an interlaboratory study conducted for certain test methods within E12. E 2480, Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method with Multi-Valued Measurands, is under the jurisdiction of Subcommittee E12.93 on Precision and Bias.
E 2480 was developed because interlaboratory studies for color involve special considerations that are not covered in other ASTM standards. The most likely users are members of the color community who deal with quality control issues in which the final result is a color difference.
The new practice is concerned with test methods that derive a multi-valued measurand, such as, but not limited to, spectral reflectance, transmittance function, tristimulus values or RGB (red, green and blue) values. Variations in measurements of such multi-valued measurands are usually analyzed by reducing the data to a single valued parameter, such as a color difference. A normal distribution does not adequately describe the results of the single valued parameter analysis. E 2480 uses a technique called bootstrapping or resampling, which does not depend on the distribution or the number of participating laboratories.
Technical Information: Hugh Fairman, Princeton, N.J.
ASTM Staff: Thomas O’Toole