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ASTM D2904, Standard Practice for Interlaboratory Testing of a Textile Test Method that Produces Normally Distributed Data, and ASTM D2906, Standard Practice for Statements on Precision and Bias for Textiles, are guides for planning interlaboratory tests to evaluate proposed test methods and for using the test results to write precision statements of normally distributed data. It is intended that these methods as well as ASTM D4467, Interlaboratory Testing of a Textile Test Method that Produces Non-Normally Distributed Data, be used as guides in the development of information for precision and bias statements in AATCC test methods.1 This monograph is a summary of the vital parts of the ASTM standards and are the minimum conditions that should be used in developing precision and bias statements for AATCC test methods. Components of variance for single operator, within laboratory, and between laboratory effects are determined.Critical differences calculated from the component variances indicate, for averages of “n” specimens from different samples, the minimum differences which are statistically significant.