National Proficiency Testing Laboratory (PTL)
National Proficiency Testing Laboratory (PTL) at the National Institute of Standards (NIS-Egypt) was started on 2007 as a working group. It was established legally as a laboratory directly under NIS president to ensure the impartiality and confidentiality. It is established to take the responsibility for all tasks in development and operation of proficiency testing schemes.
Proficiency testing, more commonly called PT, determines the performance of individual laboratories (participants) for specific test/calibration and is used to monitor laboratories’ continuing performances. PT is a means of checking and ensuring the quality of lab’s test/calibration results as stated in clause 5.9 of ISO/IEC 17025.
In a proficiency test one or more artifacts/samples are sent around between a number of participating laboratories. Each laboratory measures/calibrates the artifacts according to a given set of instructions and reports its results to NPTL. The results reported by each laboratory are compared to the assigned value. The assigned value can be determined in various ways. The two most common ways are to use a reference laboratory, reference material or use the weighted average of the values reported by the participants.
NPTL uses reference laboratories to provide the reference values. The reference laboratories are chosen by the technical advisor for the proficiency test in question based on his or her knowledge of the laboratory and the uncertainty the laboratory is able to quote for the measurand (best measurement/calibration capabilities). The reference laboratories are generally accredited laboratories (accredited for the measurand in question), which have been assessed by the technical advisor. Published CMCs also are of major concerns for National metrological organizations (NMIs)
There are different ways to evaluate the results of a proficiency test. For the type of proficiency tests offered by NPTL, the result reported by a participating laboratory for a measure and is compared to the reference value by calculating the En value (for calibration) and z or scores for testing.
PT can also validate the participating laboratory’s measurement method, technical training, traceability of standards, and uncertainty budget.