This post deals with the benefits of inter-laboratory comparisons/proficiency test participation and other uses of inter-laboratory comparisons/proficiency test data.
Inter-laboratory comparisons (ILC) require organization, performance, and evaluation of tests on the same or similar test items by two or more laboratories in accordance with pre-determined conditions. Proficiency testing (PT) is an evaluation of participant performance by means of inter-laboratory comparisons. Participation in PT activities offers laboratories many benefits beyond just meeting the requirements of ISO/IEC 17025:2017.
Outside of accreditation requirements, many different parties, such as regulators, direct customers, indirect customers, and professional bodies, have a vested interest in the PT activities of the laboratory. Successful participation in ILC/PT activities promotes confidence among external interested parties as well as laboratory staff and management. Regular participation in proficiency testing supplements the laboratory’s internal quality control activities with an external assessment of its testing or measurement capabilities. When the laboratory is willing to have its testing or measurement performance evaluated through PT, this provides added confidence to interested parties.
Laboratories can use ILC and PT data to compare their performance to that of other participating facilities. In addition, ILC/PT may be a means of comparing analytical data obtained from different methods. The laboratory may evaluate new methods against existing methods, or trial performance of a method that is new or irregularly conducted in the laboratory. ILC/PT results can also support method validation by demonstrating method precision and accuracy and providing valuable data for the estimation of measurement uncertainty.
ILC and PT activities can be used to demonstrate capability, confirming competent performance of a method, or to compare operator capabilities, providing operator repeatability data for use in estimates of measurement uncertainty. Confirming competent performance provides laboratory management with assurance that the laboratory’s performance is satisfactory, or alerts management that potential problems exist in the laboratory.
Participation in ILC and PT provides management with external monitoring of the continuing effectiveness of the management system in relation to relevant tests or measurements involved. Additional personnel education, training, and competence monitoring can result from the evaluation and analysis of proficiency testing data as well.
Participation in certain ILC and PT may also be used to assign the certified value and to estimate the uncertainty of this value for certified reference materials.
Laboratories must plan participation in PT or ILC or both. A PT four-year plan must be documented to ensure annual participation and adequate coverage of the laboratory’s scope of accreditation within the four-year period. A well-developed PT plan can ensure the laboratory gets maximum benefit from participation in PT, as well as the data generated from the PT activities.
For additional ways your laboratory can build confidence in the testing or measurement results generated, listen to the ANAB webcast “Overview of Clause 7.7 – Ensuring Validity of Results.”