NOTE: This version of "Selection, use and interpretation of proficiency testing (PT) schemes by laboratories" has been superseded by the latest edition, published in 2021. The 2021 edition can be found here.

This document represents the current state-of-the-art with respect to the selection and use of proficiency testing schemes, and the interpretation of results and evaluations given in proficiency testing schemes. Although this is aimed primarily at staff in analytical laboratories, it is also useful for customers of laboratories, assessors working for accreditation bodies and other external users of PT scheme results.

The main topics covered by the Guide are:

a) the aims and benefits of participation in PT schemes;
b) selecting the most appropriate PT scheme;
c) understanding the basic statistics and performance scoring used by the PT providers;
d) using and interpreting the PT results in order to improve the overall performance of the laboratory.