Proficiency Testing (PT) Schemes entail the organisation, development and evaluation of tests of the same items or similar items by several laboratories, according to predefined conditions. It is a requirement of ISO 17025 that laboratories participate in inter-comparison programs and/or PT schemes. In addition, any laboratory that wishes to prove the quality of its analytical results in an independent manner should participate in PT schemes, since the integrity of the analytical results is directly linked to the quality of service or product, as well as market credibility and brand image offered by the service provider.
Participation in PT schemes is an essential tool to demonstrate the technical competence of a laboratory as it allows for the following:
- Comparison of a laboratory’s own results with those obtained by other laboratories;
- Confirmation of the correct initial validation of a method;
- Use the data obtained from participating PT schemes for validation of measurement methods;
- Determine systematic errors;
- Improve the test method used;
- Learn from the methods used by other laboratories;
- Monitor the accuracy and precision of a method;
- Encourage collaboration between laboratories; and
- Demonstrate technical competence against third parties.