Proficiency tests (PT) define the ability of the laboratory and/or analyst to carry out the
procedures of the method with acceptable precision and accuracy. Participation in a
interlaboratory comparisons or proficiency test programs is a requirement of ISO/IEC
17025:2005. CALA’s policy on PT states that all accredited laboratories shall
demonstrate their technical competence by the satisfactory participation in a suitable
proficiency testing activity. All analytes appearing in the laboratories Scope of
Accreditation must be supported by PT. Typically the laboratory must demonstrate this
ability twice a year. Participation in interlaboratory testing also enables the laboratory to
monitor their performance and compare their results with other laboratories performing
the same analysis.