Interlaboratory Study Program
ASTM's Board of Directors adopted plans, in the fall of 2004, to launch the Interlaboratory Study Program (ILS) as part of their continuing pursuit of excellence in standards development. Responding to the need for standards in the marketplace to be of known and documented quality, a commitment was made to fund the development of the ILS Program. This commitment means that ASTM has been able to assist those technical committees for which the prospect of implementing an interlaboratory study was either administratively daunting or financially impossible. The ultimate goal is to enhance the quality of ASTM standard test methods by aiding the Technical Committees as they develop Precision Statements backed by high quality laboratory data.
In order to support the committees in their efforts to produce precision statements for their test methods, so as to incorporate at least a repeatability statement, the ILS Program is available to assist with the following areas:
- Designing an Interlaboratory Study
- Identifying potential samples
- Soliciting volunteer laboratories
- Finding an available supplier
- Contracting with a distributor
- Reviewing laboratory instructions
- Reimbursing shipping expenses
- Collecting data
- Analyzing data
- Producing a draft precision statement
- Compiling information for the Research Report
- Recognition of participating labs
Once a Work Item has been registered (instructions here), new programs should be registered through the Interlaboratory Study (ILS) link in the My Tools section of the member's MyASTM page, available after logging into ASTM's website.
Interlaboratory Study (ILS) Process
- Work Item - register a work item (if you have not done so already).
- Registration - register the ILS through the MyASTM area of the website.
- Conference Call - The Technical Contact (TC) will be contacted by ASTM to set up a conference call to discuss the ILS. During this call the TC should be prepared to discuss the following information: test specimens, lab supplies, potential suppliers, a distributor, a potential list of labs, and what data should be collected as part of the study.
- Samples - if assistance is needed with finding and/or ordering materials to be tested, ASTM can provide support.
- Sample Funding - ASTM has funds available to assist with purchasing samples, sample preparation and shipping. After a proposal of costs is developed, ASTM will work with the committee to determine how much assistance can be provided.
- Lab Solicitation - if there are not enough labs to do the testing, ASTM can send out a solicitation to the committee looking for volunteers.
- Lab Instructions - the study instructions should be developed and finalized before samples are distributed. Please send them to ASTM for review.
- Data Report Forms - ASTM will collect the study data using an online data report form or an excel data report form (depending on the amount/complexity of the data). The data report form will be sent to the technical contact for review before the labs receive it.
- Sample Distribution - once the study materials have been purchased, it may be necessary to send them to a distributor for final prep and packaging (may be the same as the supplier).The distributor will then ship the samples. ASTM will send the data report forms and the study instructions to the labs.
- Data Submission - ASTM will track data submitted by the lab participants.
- Statistical Summary - once all of the data has been received from the labs, ASTM will then compute the repeatability and reproducibility using ASTM Statistical Software. A draft precision and bias statement will be written and sent to the TC for review.
- Research Report (RR) - to generate the RR, ASTM will utilize information collected during the ILS, including information in the online registration, study instructions, data analysis and the precision and bias statement. The draft research report will be sent to the TC for review.
- Precision and Bias Statement - the precision and bias statement (along with any other revisions to the standard) should be placed on the next ballot.
- Approval - after the ballot is approved and the research report is complete, ASTM will assign a RR#, and send out copies of the RR to the TC and the participating labs.
Precision and Bias
Additional Information: Ruggedness Testing; Pilot Testing
There are two measurements that serve to express precision in the evaluation of a standard test method. They are commonly referred to as "repeatability" and "reproducibility" and provide the boundaries between which precision exists.
- 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).
Bias, on the other hand, 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 a standard test method, this statement describes the bias and the methods utilized to provide corrected test results. 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.
As precision and bias are mandatory sections of an ASTM standard test method (per Section A.21 Form and Style for ASTM Standards), the utmost care should be taken to ensure that the final data, as well as the steps that were taken to generate the data, are as precise and accurate as possible. A standard test method that is incapable of doing what it purports can be misleading. Precision and bias statements strengthen the perceived validity of the standard test method and provide the user of the document with the added confidence of knowing that the standard test method has been laboratory tested.
Templates:
Precision and Bias Template
Repeatability Precision Template
Research Reports
ASTM has published approximately 6000 test methods to date, with more being approved every day. The backbone of many of these standard test methods is a comprehensive interlaboratory study that supports the Precision and Bias statement. When an interlaboratory study is completed, it is very important to document the details in a research report. A research report should contain a list of participating laboratories, description of samples, a copy of the laboratory instructions, the equipment/apparatus used, a copy of the raw data, a statistical summary and a copy of the precision and bias statement. The ASTM Form and Style Manual (Section A29.1) states, "Where numerical data have been generated to establish the precision and bias of a test method, a research report is required". To this end, we have developed a consistent format in the ASTM Research Report Template for you to use.
- ILS can assist with the following research report tasks:
- Answer any research report inquiries
- Create research reports from ILS studies
- Reformat older research reports to fit the ASTM research report Template
- Assign research report numbers
- A research report number will be assigned by ASTM when all of the following have been
completed:
- The research report is submitted to ILS
- It is reviewed for completeness
- The ballot item to include the corresponding precision and bias statement is approved for publication.
The published standard test method will include the research report number in a footnote to the Precision and Bias section. To obtain a copy of a research report, contact ASTM Customer Service by phone at 610-832-9585 (8:30 a.m. - 4:30 p.m. Eastern U.S. Standard Time, Monday through Friday) or by email at service@astm.org.
For assistance with research reports, please contact researchreports@astm.org.
Infographic: Interlaboratory Studies Program