Guidance on the level and frequency of proficiency testing participation

European Co-operation for Accreditation (EA) has recently issued the Advisory Document EA-4/18: 2010 “Guidance on the level and frequency of proficiency testing participation”. The aim of this paper is to promote harmonization between Accreditation Bodies on how the level and frequency of participation in PT is evaluated and to assist laboratories in determining their own levels and frequency of participation. Moreover, a number of case studies is provided to illustrate how a laboratory might review their scope of work and thus derive the number of sub-disciplines.