GLEMP members benefit from the cost-sharing access to well-developed performance evaluation (PE) data for GLEMP participating laboratories. Access to this valuable data allows the GLEMP member representative to differentiate the quality and accuracy capabilities of laboratories. This focus can be from the perspective of monitoring their current commercial laboratory service providers, or to narrow the list of candidate commercial laboratories to those demonstrating a recurring capability of attaining highly accurate results.
The idea of using inter-laboratory studies to evaluate laboratory performance has received widespread application in only the past fifteen years. The first ISO Harmonized Protocol was issued in 1990. Proficiency testing (PT) is essentially using inter-laboratory round-robin or "ring studies" to evaluate the performance of laboratories in a critical manner using an established set of agreed statistical protocols. Proficiency testing (PT) programs by design judge laboratory performance and determine acceptability based upon the established statistical standard.
In contrast to proficiency testing (PT), performance evaluation (PE) programs provide more information about overall laboratory and method performance through comprehensive data reporting and do not judge the adequacy of the performance of any laboratory. The concept behind proficiency testing (PT) is judgment against a standard while the concept behind performance evaluation (PE) is laboratory quality improvement through fair, accurate, inter-laboratory comparison against peer laboratories to establish relative performance and improve quality assurance.