Conducting Interlaboratory Studies
All ASTM International test methods are required to include statements on precision and bias. A new ASTM guide provides an overview of the steps needed in an interlaboratory study to obtain precision and bias statements, particularly as they relate to standards for petroleum products.
The new standard, D7778, Guide for Conducting an Interlaboratory Study to Determine the Precision of a Test Method, was developed by D02.94, Coordinating Subcommittee on Quality Assurance and Statistics, part of ASTM International Committee D02 on Petroleum Products and Lubricants.
According to Alex Lau, president, TCL Consulting, and chairman of D02.94, Coordinating Subcommittee on Quality Assurance and Statistics, D7778 is the answer to increasing requests from D02 members for interlaboratory study guidance. D7778 has been specifically developed as a companion document to another D02 standard, D6300, Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants. While D6300 is focused on statistical treatment of data, D7778 contains guidance on the planning and management of an interlaboratory study.
D7778 includes templates for ILS plan development and data return forms, as well as examples of a letter from ILS coordinators to participants, a questionnaire to collect relevant ILS testing information and a testing protocol. Lau notes that these sample documents have been developed based on more than 40 years of D02 ILS planning and execution.