Due to non availability of an appropriate PT scheme in many area of testing laboratories seeking recognition of their competence through accreditation against the standards ISO/IEC 17025 are facing problem.

In some sectors participation in specific schemes can be mandatory. PT schemes are operated for the benefit of participants. However, other parties also have a genuine interest in PT schemes. These include customers of analytical laboratory services, accreditation bodies, regulatory authorities and other end-users of laboratory results. It is important for PT providers to put up with in mind the needs of these organizations in order that they are able to use the results from PT schemes to assist their understanding of the capabilities and competence of laboratories.

It is significant for laboratories to have complete information on the accessibility and scope of PT schemes in the areas in which they work. This will allow them to make appropriate decisions about which PT scheme(s) they should participate in. It is important that this type of information is broadly available in order for laboratories to be able to select the most appropriate PT scheme.

Laboratories also require having a good considerate of PT, what the objectives of the PT schemes are, any limitations, how the data is evaluated by the PT provider, and how the data from PT schemes should be internally evaluated and used.

In this Guide, the term “measurement” is used generally for measurements undertaken in both calibration and testing. The term “examination” is understood to include examination of both quantitative and qualitative characteristics. For conciseness, unless otherwise qualified, provisions on measurement of a PT item, measurement procedures etc. should be read as applying equally to any laboratory activity leading to a reported proficiency test result, whether quantitative, qualitative or interpretive. 

Inter Laboratory comparison (ILC)
Organization, performance and evaluation of measurements or tests on the same or similar items by two or more laboratories in accordance with predetermined conditions.

Proficiency testing (PT)
Evaluation of participant performance against pre-established criteria by means of inter laboratory comparisons NOTE some providers of proficiency testing in the medical area use the term External Quality Assessment for their proficiency testing schemes and/or for their broader programmes.

Proficiency testing scheme (PT scheme)
Proficiency testing designed and operated in one or more rounds for a specified area of testing, measurement, calibration or inspection.

Proficiency test item (PT item)
Sample, product, artifact, reference material, piece of equipment, measurement standard, data set or other information used for proficiency testing.

Proficiency testing provider (PT provider)
Organization which takes responsibility for all tasks in the development and operation of a proficiency testing scheme

Participant
Laboratory, organization or individual, that receives proficiency test items and submits results for review by the proficiency testing provider NOTE In some cases the participant can be an inspection body.