Developing a Precision and Bias statement using an Interlaboratory Study can be a complicated process, but our experienced team is here to help. Contact the ILS Team for assistance with:
The Interlaboratory Study Program is provided at no cost as a benefit for all ASTM members to help you meet the precision statement requirements in ASTM test methods.
Designing an interlaboratory study
Identifying potential samples
Soliciting volunteer laboratories
Finding an available supplier
Ordering and purchasing samples
Contracting with a distributor
Reviewing laboratory instructions
Shipping expenses
Collecting and analyzing data
Producing a draft precision statement
Compiling information for the Research Report
Recognition of participating labs
All ASTM standard test methods must include a precision and bias statement, per Section A.21 of the Form and Style for ASTM Standards of the Form and Style for ASTM Standards. These statements strengthen the perceived quality of the standard test method. They also let users know that a test method has been laboratory tested.
The two measurements that serve to express precision in the evaluation of a standard test method are repeatability and reproducibility:
Repeatability - addresses variability between independent test results gathered from within a single laboratory (otherwise known as intralaboratory testing)
Reproducibility - addresses variability among single test results gathered from different laboratories (otherwise known as interlaboratory testing).
While Bias is defined as a systematic error that contributes to the difference between the mean of a large number of test results and an accepted reference value. When included in an ASTM test method, this statement describes the bias. It is important to remember that if an accepted reference value is not available, then the bias cannot be established. However, if the bias is unknown but the direction or bounds of the bias can be estimated, this information should be included in the bias statement.
Additional Information: Ruggedness Testing; Pilot Testing
We have created custom templates to assist you in drafting your Precision and Bias Statements:
Precision and Bias Template
Repeatability Precision Template
Comprehensive interlaboratory studies are a key component in the development of a Precision and Bias statements. When an interlaboratory study is completed, it is important to document the details in a research report.
Per Section A29.1 of the Section A29.1 of the ASTM Form and Style Manual, research reports are a requirement when numerical data is used to establish the precision and bias of a test method. Research Reports must include:
a list of participating laboratories
a description of samples tested
a copy of the laboratory instructions
the equipment/apparatus used
a copy of the raw data
a statistical summary
a copy of the precision and bias statement
Our ILS team is here to help you when developing your Research Report. Contact us for assistance with general research report inquiries such as:
generating research reports from ILS projects
reformatting older reports to fit the ASTM Research Report Template
obtaining research report numbers
Once you’ve completed your full report, you will submit to our ILS team and it will be reviewed for completeness.
Once your ballot item is approved for adding your precision and bias statement to a test method, we’ll assign a new research report number. The published standard test method will include this number. Contact ASTM to request a copy of your research report.
Download the infographic: Interlaboratory Studies Program
