Accredia / Accredited services / Proficiency testing

Proficiency testing

Interlaboratory comparisons

Accredited interlaboratory tests are evaluations of the performances of a laboratory in accordance with criteria, by means of comparisons with other laboratories.

Interlaboratory comparisons are managed by accredited providers in compliance with ISO/IEC 17043, known as Proficiency Testing Providers (PTP). They consist of the performance, by accredited laboratories, of tests which are recognized by adequate documents, on identical or similar materials, and of their evaluation against objective criteria.

Interlaboratory comparisons enable a lab to compare its operations with those of other laboratories, so as to have a comparison of the results or to enquire into a potential problem.

The evaluation of the performances of a testing, medical or calibration lab is a periodical, objective, independent and documented verification of the quality of the analyses routinely carried out. Participation at a proficiency test is an instrument of self-control which helps to improve the quality of services.

The objectives

In accordance with ISO/IEC 17043, accredited laboratory tests are undertaken:

  • to evaluate tests and measurements and to monitor the performances of laboratories on a continuous basis;
  • to identify issues and implement improvement actions related, for example, to test procedures or inadequate measurements, to training failures and staff supervision or to the calibration of equipment;
  • to define the effectiveness and ways of comparing test or measurement methods;
  • to guarantee greater reliability for the laboratory’s clients;
  • to train laboratories taking part in proficiency tests on the basis of the results of comparisons;
  • to validate declarations of uncertainties.

Requirements for participation

Participation at interlaboratory comparisons must be carefully planned by the accredited laboratories as a part of their activities for ensuring the quality of their results.

The accredited Proficiency Testing Scheme at which the laboratory takes part should be as similar as possible to the activities which the laboratory itself usually undertakes, in terms of the sampling of measurements, test materials and types of measurements. Testing activities on samples for the proficiency test must be done using ordinary work processes, without any particular treatments.

The analysis of interlaboratory proficiency test results must be included in the broader quality management system review: the data obtained by these tests will give the laboratory information regarding the conformity of its operations, indicating whether they are satisfactory or if any potential issues emerged requiring correction actions.

During the assessment of the results it is necessary to take into account any measurement uncertainties, especially concerning repeated statistically non-conform results. When this happens it is necessary to discover the causes of the error, which may have passed unnoticed. The laboratory must show that it takes into consideration the results of the circuit, implementing the necessary preventive and corrective actions.

The advantages

Successful activities obtained from a regular series of interlaboratory comparisons spread trust in the reliability of the services provided.

The choice of the laboratory to regularly undergo the checks and evaluations of its measuring activities by means of an accredited proficiency test constitutes a guarantee of quality.

An examination of analytical performance makes it possible to demonstrate objectively that the performance is reliable in the eyes of clients, suppliers, control bodies, accreditation bodies and the regulatory authorities.

Accredited proficiency testing providers

Interlaboratory comparisons are organized by accredited PTPs according to the ISO/IEC 17043.