The purpose of this Technical Specification is to specify a validation procedure to show if an Alternative Method (AM) can be used as an alternative to the Standard Reference Method (SRM), both implemented to determine the same measurand. This document has been drawn up for laboratories working in air pollution measurements (and consequently examples taken from this sector are included in the appendices).In particular, this Technical Specification provides the statistical tools and different criteria to evaluate the alternative method; this does not release the person responsible for this validation from bearing technical and analytical judgement on the eva