Proficiency testing is conducted to confirm the competence of labs to perform sepcific test/calibration by an interlaboratory comparison using the same sample/artefacts.
In the assessment for the accreditation of laboratories, the results of proficiency testing play an important role to support and complement assessment process on the technical aspects.

Why is Proficiency Testing neccesary ?

For the international standards related to the laboratory accreditation, the necessity of the proficiency testing is prescribed as follows.

• The laboratory shall have quality control procedures for monitoring the validity of test and calibrations undertaken.... b) participation in interlaboratory comparison or proficiency testing programs; ... (ISO/IEC 17025 5.9)
• The accreditation body shall ensure that its accredited laboratories participate in proficiency testing or other comparison programmes, where available and appropriate, and that corrective actions are carried out when necessary. (ISO/IEC 17011 7.15.3)

Schemes of Proficiency Testing

The Technique of the proficiency testing is changed according to the property of the test/calibration item, a test/calibration method to be used, and the number of the participating laboratories, etc. Typical cases are illustrated as follows.

1. Testing field : Interlaboratory testing schemes

Sub-samples randomly selected from a material source are simultaneously distributed to the participating laboratories. After completing the testing, respective results are returned to the coordination body and compared with an assigned value to give an indication of the performance of the individual laboratory and a group as a whole group.
An example of Interlaboratory testing scheme (the arrows show the distribution of the sample)

2. Calibration Field : Measurement comparison schemes

Item/Artefact to be measured or calibrated is circulated successively from one participating laboratory to the next.
This is often called as Round-robin test.
Cases of measurement comparison schemes (the arrows show the circulation of the item)

3. (Reference) Standards of Proficiency Testing

• ISO/IEC Guide 43-1 Proficiency testing by interlaboratory comparisons
Part 1: Development and operation of proficiency testing schemes
(JIS Q0043-1:1998)

• ISO/IEC Guide 43-2 Proficiency testing by interlaboratory comparisons
Part 2: Selection and use of proficiency testing schemes by laboratory accreditation bodies
(JIS Q0043-2:1998)