All ASTM test methods are required to include statements on precision and bias.

Since ASTM began to require all test methods to have precision and bias statements that are based on interlaboratory test methods, there has been increased concern regarding what statistical experiments and procedures to use during the development of the test methods. Although there exists a wide range of statistical procedures, there is a small group of generally accepted techniques that are very beneficial to follow. This document is designed to provide a brief overview of these procedures and to suggest an appropriate sequence of carrying out these procedures.

Statistical procedures often result in interpretations that are not absolutes. Sometimes the information obtained may be inadequate or incomplete, which may lead to additional questions and the need for further experimentation. Information outside the data is also important in establishing standards and in the interpretation of numerical results.

FIG. 1 Sequence of Steps

1.1 This guide identifies statistical procedures for use in developing new test methods or revising or evaluating existing test methods, or both.

1.2 This guide also cites statistical procedures especially useful in the application of test methods.