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ASTM C670-03
Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials

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1.1 This practice supplements Practice E 177, in order to provide guidance in preparing precision and bias statements for ASTM test methods pertaining to certain construction materials (Note 0). Recommended forms for precision and bias statements are included. A discussion of the purpose and significance of these statements for the users of those test methods is also provided.

Note 1—Although under the jurisdiction of Committee C-9, this practice was developed jointly by Committees C-1, D-4, and C-9, and has been endorsed by all three committees. It has subsequently been adopted for use by Committee D-18.


This practice provides guidance in preparing precision and bias statements for ASTM test methods pertaining to construction materials. Test method shall conform to the maximum acceptable range of individual measurements. In order to be valid the indexes of precision to be included in the precision statement as guides for the operator must be based on estimates of the precision of the test method obtained from a statistically designed inter-laboratory series of tests. This series of tests must involve a sufficient number of laboratories, materials, and replicate measurements so that the results obtained provide reliable estimates of the true precision characteristic of the test method. The procedures described in this practice are based on the assumption that the proper estimates of precision have already been obtained. In any test method, tolerances are placed on the accuracy of measuring equipment. All tests made with a given set of equipment which has an error within the permitted tolerance will produce results with a small consistent bias, but that bias is not inherent in the test method and is not included in the bias statement for the test method. There are two conditions which permit the bias of a test method to be estimated: a standard reference sample of known value has been tested by the test method, and the test method has been applied to a sample which has been compounded in such a manner that the true value of the property being measured is known, such as may be the case, for example, in a test for cement content of concrete.

This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

General Product Information

Document Type Standard
Status Superseded
Publisher:    American Society for Testing and Materials
Committee C 09
Superseded Date 09 Nov 2010
Superseded By:
ASTM C670-10
ASTM C670-96

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Published:   10 Jan 2003  
Pages: 9
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Published:   10 Jan 2003  
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CONTAINED IN VOL 04.02, 2005

Advises on preparing precision and bias statements for ASTM
methods pertaining to certain construction materials. Includes
recommended forms for precision and bias statements.


2003 [24/03/2003]
96 [01/07/1996]
95 [01/11/1995]
91A [15/03/1991]
90A [30/11/1990]
90 [30/03/1990]

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