The proficiency test is a tool to determine the influence of parameters which may vary between individual laboratories, it does not represent a substitute for the calibration procedure, the use of calibrated equipment is taken for granted.

The participation in the proficiency test scheme is open for all testing laboratories with a specific experience in chosen methods, the extent of the method selection is free.

The proficiency test is run and evaluated according to the ISO 17043 and ISO 13528. The assigned value is set by OFI-pts team. It is determined by means of precision tests with the uniform testing, measuring or analysing method (mean from 10 single measurements). Metrological traceability is ensured since the result is determined by a test institute accredited in accordance with EN ISO/IEC 17025.

The criteria for performance evaluation is defined on the basis of the applicable test standard (whenever available) of the uniform testing procedure. Whenever the test standard included a reproducibility standard deviation sR, the relative reproducibility standard deviation sR,rel will be converted based on the assigned value. If several reproducibility standard deviations were given, the mean of the relative reproducibility standard deviations is used (rounding within the standard deviation is admissible). If no precision data were given in the applicable test standard, the standard deviation for proficiency assessment (σpt) will be calculated on the basis of prior proficiency tests. In this case, the latest three rounds are used and the mean of the relative reproducibility standard deviations sR,rel will be calculated. It is then converted based on the assigned value.

The "z-score" and “zeta -score” is the measure of the laboratory performance.

The "z-score" gives an information about the bias of the laboratory result and can be used as a documentation of the lab performance for third parties and supervisory bodies. The “zeta score” is a measure of a participant's ability to achieve results that are closer to the assigned value than their stated uncertainties.

The identity of the participants is handled confidentially and the anonymity of the results is safeguarded by the allocation of the LabCodeNumbers to the participants.