ASTM E691-19e1 Standard Practice for Conducting Interlaboratory Studies to Determine the Precision of a Test Method

Published by the American Society for Testing and Materials (ASTM), the ASTM E691-19e1 standard describes methods for planning, conducting, analyzing, and processing results of interlaboratory work for a test method. The statistical methods described in this standard provide sufficient information to formulate the precision statement of a test method. The full name of this standard is as follows: ASTM E691-19e1 Standard practice for conducting an interlaboratory study to determine the precision of a test method.

This standard also deals with test methods that give a single numerical figure as a test result. But a single figure can be the result of a calculation after a series of measurements. ASTM applications require precise statements in all test methods for repeatability.

When a test method is applied to as many parts of a material that are as similar as possible, not all test results obtained have the same value. A measure of the level of agreement between these test results defines the precision of the test method for that material. More variability means weaker precision and greater uncertainty.

Precision is reported as standard deviation, coefficient of variation, variance or precision limit. This application is only designed to estimate the precision of a test method.

The application included in the ASTM E691-19e1 standard offers procedures consisting of three basic steps:

• Planning interlaboratory work
• Guiding the test phase of the study
• Analyzing test result data

The planning phase includes the creation of the interlaboratory task group, study design, selection and number of laboratories involved, selection of test materials and writing the protocol. The test phase includes material preparation and distribution, communication with participating laboratories, and processing of test result data from laboratories. In the data analysis process, tables, graphs and statistical diagnostic tools are used to evaluate the consistency of the data.thus, extraordinary values ​​are detected and researched.

With the experience gained over many years, our organization also provides standard application services for conducting interlaboratory studies to determine the precision of a test method, ASTM E691-19e1, within the framework of laboratory services of materials with a trained and expert staff.