Many laboratories take part in proficiency testing schemes, external quality assessment programmes and other interlaboratory
comparisons. These have many similarities but also important differences in their
modus operandi and evaluation of performance of participating laboratories
. This paper attempts to highlight both the similarities and differences. It also puts particular emphasis on requirements
called ”target values for uncertainty” and their meaning.
Keywords External quality assurance - Interlaboratory comparisons - Proficiency testing - Target values for uncertainty
Received: 24 January 2001 Accepted: 25 January 2001