Standard Withdrawn, No replacement   Last Updated: Dec 31, 2010
ASTM D2906-97(2002)

Standard Practice for Statements on Precision and Bias for Textiles (Withdrawn 2008)


1.1 This practice serves as a guide for using the information obtained as directed in Practice D 2904 or obtained by other statistical techniques from other distributions, to prepare statements on precision and bias in ASTM methods prepared by Committee D-13. The manual on form and style for standards specifies that statements on precision and bias be included in test methods. Committee D-13 recommends at least a statement about single-operator precision in any new test method, or any test method not containing a precision statement that is put forward for 5-year approval, in both instances with a complete statement at the next reapproval. If a provisional test method is proposed, at least a statement on single-operator precision is expected.

1.2 The preparation of statements on precision and bias requires a general knowledge of statistical principles including the use of components of variance estimated from an analysis of variance. Instructions covering such calculations are available in Practice D 2904 or in any standard text (1,2,3,4, and 5).

1.3 The instructions in this practice are specifically applicable to test methods in which test results are based ( 1) on the measurement of variables, (2) on the number of successes or failures in the specified number of observations, (3) on the number of defects or incidents counted in a specified interval or in a specified amount of material, and ( 4) on the presence or absence of an attribute in a test result (a go, no-go test). Instructions are also included for methods of test for which precision has not yet been estimated or for which precision and accuracy have been reported in another method of test. For observations based on the measurement of variables, the instructions of this practice specifically apply to test results that are the arithmetic average of individual observations. With qualified assistance, the same general principles can be applied to test results that are based on other functions of the data such as standard deviations.

1.4 This standard includes the following sections:

Section No.
Attributes, Statements Based on15
Binomial Distributions, Calculations for9
Binomial Distributions, Statements Based on13
Categories of Data7
Computer Preparation of Statements Based on Normal or Trans-formed Data12
Normal Distributions and Transformed Data, Calculations for8
Normal Distributions and Transformed Data, Statements Based on11
Poisson Distributions, Calculations for10
Poisson Distributions, Statements Based on 14
Precision and Bias Based on Other Methods16
Precision Not Established, Statements When17
Ratings, Statements Based on Special Cases of18
Sources of Data6
Statistical Data in Two Sections of Methods5
Significance and Use4
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