What is Proficiency Testing?
Proficiency Testing (PT) is the name used by the International Standards Organization for a procedure also known as “inter-laboratory study” or “external quality assessment” or “ring test”. Proficiency testing, in simple terms, comprises a sample sent to a group of laboratories for measurement. The labs know what might be in the sample, but they don’t know exactly what is there or the concentration. Their results are compared with the known or true value and the lab is assigned a “Z” score to show how closely their result came to the target.