Guidance on Precision and Bias / Frequently Asked Questions


What is the cost of the E691 software?

ASTM will provide on loan a copy of the E691 software to an ASTM member for the purpose of working on a precision statement of a test method. ASTM does require that when the committee.s work with the software is completed, the software be returned to ASTM. Please contact your staff manager if you would like to obtain a copy on loan. If a person, lab, etc. wishes to purchase E691 for personal or company use, the software or a hard copy can be purchased from the ASTM website www.astm.org.


What should I do with the Round Robin data? Does ASTM keep it on file?

Once the round robin has been completed and the information has been balloted into the test method, the data shall be submitted to ASTM to be kept on file as a Research Report. A number will be assigned to the research report and a note will appear in the precision and bias section of the test method referencing the specific research report. A research report should be organized according to the Guide for the Format of a Research Report


Who absorbs the cost of round robin testing?

In most cases, industry will assume the cost of round robin testing. An organization volunteers to prepare and distribute samples to laboratories that volunteer to perform testing to generate precision and bias data. In limited cases, funding is obtained to cover some of the expenses associated with management of the round robin program.


Who can I contact at ASTM HQ if I need help understanding E691 or using the software?

The staff manager for your technical committee serves as the initial point of contact for all inquiries. The manager will be able to refer you to the appropriate resource to answer your question. You will often be referred to a member of the committee that developed E691 . Committee E11 on Quality and Statistics.


Can a single company with multiple labs consider each lab as a separate testing site to reach the required # of labs in E691?

Yes. As long as each data set is generated by a laboratory with its own set of conditions, calibrations, and equipment condition and is then compared to other laboratories with their own set of variables, the separate testing site requirement is met.


How long can we wait after developing a test method to include a P&B statement?

It is recommended that ruggedness testing and an interlaboratory testing program be completed before approval of a new test method. However, if a committee determines that a delay is necessary to conduct a round robin, a temporary statement addressing repeatability conditions is permitted for five years. Included in that statement shall be language regarding the date of actual availability of reproducibility data.


Does ASTM require strict compliance with E691?

ASTM requires strict compliance with The Form & Style for ASTM Standards, which mandates that a precision and bias section be included in all test methods. A means toward achieving that end can be E691, or a standard based upon E691 that has been developed by an ASTM Committee.


Can a committee publish a P&B statement if E691 wasn't used?

Yes. Section A21.2.7 of The Form & Style for ASTM Standards indicates that a precision statement shall be developed in accordance with the test program prescribed in E691 or by an interlaboratory test program that yields equivalent information. Several ASTM Committees have developed standards based on E691 but met other needs of their industry.


What happens if we find an old test method without a P&B statement? Is it grand-fathered?

The Form and Style for ASTM Standards mandates that all test methods contain a precision and bias statement. If a test method is discovered that does not contain this section, an evaluation should be immediately performed to determine the utility of the document and steps should be undertaken to address precision and bias.


What happens if we can't produce the 6 labs that E691 requires? Will the software still work?

The E691 software is designed to work optimally when data from a minimum of six laboratories is entered. the greater the number of participating laboratories, the smaller the chance that lab-to-lab variability will be an issue. However, it is possible to generate a precision statement with less than six participating laboratories; the bottom line is that some precision information is preferable to no precision information.