What is proficiency testing

The upcoming proficiency testing standard ISO/IEC DIS 17043 (which is to supercede ISO Guide 43) defines:

• Proficiency testing (PT) as the evaluation of participant performance against pre-established criteria by means of interlaboratory comparisons and

• Interlaboratory comparisons (ILCs) as the organisation, performance and evaluation of measurements or tests on the same or similar items by two or more laboratories in accordance with predetermined conditions.

  
  

A single proficiency testing event is often named PT or PT round. A series of coherent rounds having a certain frequency of operation is usually called a PT scheme. PT is also referred to as external quality assessment (EQA) in the medical field.

PT schemes operate in much the same manner regardless of the measurement to be made. The provider of the PT distributes (or specifies the location of) one or more test items to the participating laboratories for measurement. The participants have no knowledge of the true measurement value or its best estimate. They perform the requested measurements on the test items and report to the PT provider who evaluates their results. For a large majority of PT schemes this evaluation takes the form of a calculated score that reflects the performance of each participating laboratory. Laboratory identities remain undisclosed to ensure the confidentiality of the individual participants. The test item is usually a sufficiently homogeneous and stable material, aliquots of which are distributed to the participating laboratories; it may also be a single artefact which is tested by laboratories in sequence. The former is common to conventional testing, the latter to the field of calibration.

ILCs may also be used by participating laboratories and other parties for a number of purposes other than PT, including the validation of analytical methods, the certification of reference materials, the monitoring of individual staff performance, etc.