Proficiency Testing

Participation in Proficiency Testing

Proficiency testing is one of the most effective ways for a laboratory to compare its performance against its own requirements and the general level of performance of other participants.

Each round involves distributing a sample of established homogeneity to participating laboratories. These laboratories are required to analyse the sample using an established technique operated under routine analytical conditions. The results must be returned to the organisers by a deadline. Data for each element contributed by participating laboratories are compared with an assigned value and a ‘z-score’ calculated. The magnitude of the ‘z-score’ allows each contributing laboratory to assess the accuracy of their analytical results in comparison with the other participating laboratories.

The overall aim is, therefore, to enable laboratories to decide whether their analytical performance was satisfactory. If they judge this not to be the case after an evaluation of data published in a report of the round, participating laboratories have the opportunity to investigate analytical discrepancies and correct their procedures, if necessary.

The GeoPT proficiency testing programme is now well established and widely used by university, research and commercial laboratories involved in the analysis of silicate rocks. Samples are normally distributed every six months. Results from contributing laboratories will be regarded as confidential, with data being published anonymously, although a general list of contributing laboratories will be included in each final report. Participation is welcome from all laboratories, whether or not they participated in previous rounds.

IAG runs two proficiency testing programmes: (i) GeoPT for the analysis of silicate rocks, and (ii) G-Probe for microprobe analysis.