Inter-Laboratory Comparison / Proficiency Testing (ILC/PT) means organisation, implementation and evaluation of the results of measurement or testing of the same or similar test items/samples carried out by two or more than two laboratories against pre-established criteria.

The main purpose of ILC/PTs is to assess the competence of laboratories undertaking specific tests, measurements or calibrations. ILC/PTs range among the most important tools used by a laboratory to monitor and control the quality of performance of its accredited activities and the results, and their comparability to the results of other laboratories active in the same field. The results obtained through ILC/PTs enable the identification of possible problems, and they are particularly important for verification of the laboratory’s work when introducing changes or new activities.

Participation in ILC/PTs will bring best benefits to the laboratory, its staff and management, if they accept it as a key tool to continuously maintain confidence and improve.

Read more on the benefits and advantages derived from participation in ILC/PTs in the publication issued by ILAC. The Slovene translation of the brochure is also available.

Requirements for participation ILC/PTs

Participation in relevant ILC/PTs, when available, is one of the criteria for the laboratory to obtain and maintain accreditation. When this is required for providing confidence in the laboratory’s results, it has to take part, regularly and within the relevant scope, in ILC/PTs. Participation requirements apply to all calibration and testing laboratories as well as other CABs that perform testing or calibration within their scope of conformity assessment procedures. For the accredited activities for which appropriate ILC/PTs are not practicable or available, the laboratory may use other ways of ensuring the quality of its results.

Slovenian Accreditation requires participation in ILC/PTs – when available – at least once before the grant of accreditation, and subsequently, at least once during the period between two reassessment visits (four years), in each of the larger sub-areas within the laboratory’s scope of accreditation.

For the needs of assessment visits, the laboratories shall report of their participation and the results using the form OB05-18, Proficiency testing review.

Particular attention in assessing a laboratory is paid to checking the control of the results of participation in ILC/PTs and to implementing corrective action in the case of deviations.

Read more on the requirements for ILC/PTs and on the review of ILC/PTs in accreditation procedure in the document OA05, Participation in interlaboratory comparisons.