10 Interlaboratory Comparisons
173
EA-4/18:2010
Level of participation: the number of sub-disciplines that an organization identifies within its scope, and therefore the number of specific proficiency tests
that should be considered for participation.
Frequency of participation: how often a laboratory determines that it needs to
participate in PT for a given sub-discipline; this may vary from sub-discipline
to sub-discipline within a laboratory and between laboratories with the same
sub-disciplines.
Sub-discipline: an area of technical competence defined by a minimum of one
measurement technique, property and product, which are related.
Evaluation of the results of interlaboratory comparison/proficiency testing
Test and calibrating laboratories should strive to participate as often as possible in
various ILC/PT, most of all because it is an incredibly important tool enabling the
external evaluation of the quality of reporting results. Moreover, it is also possible to
evaluate the reliability of the measuring procedures used. In each ILC/PT scheme, the
main objective of the laboratory is to perform measurements for the object (sample)
delivered by the provider, preferably under conditions typical to everyday practice in a
given laboratory. Results obtained in the laboratory are then compared to the reference
value assigned by the provider, and the evaluation of the laboratory performance
includes the use of a selected score that classifies the given result in relation to the
reference value.
Satisfactory result within the applied score: laboratory confirms its competencies in the scope of the measurements conducted.
Questionable/unsatisfactory result within the applied score: corrective action
should be applied (the laboratory should conduct a detailed analysis of the
measuring procedure used and the environmental conditions).
The main objective of participating in ILC/PT is to evaluate the performance of
a given laboratory by comparing the result obtained by a laboratory (X lab ) with the
reference value (X ref ) versus the accepted target range. As previously mentioned, the
evaluation criteria should be provided to the participants by the ILC/PT provider.
Thus, the laboratory can critically evaluate the statistical tools used by the organizer
to reject the extreme values, to determine the reference values and to specify the evaluation criteria. All this information should be placed in the report, together with the
results of the participating laboratories. That information is necessary for the critical
assessment of the results obtained and, if the need arises, for using criteria stemming from legislative requirements or agreed upon with a customer. It is extremely
important in view of the need to analyze the results of the comparisons (ILC/PT) by
173
EA-4/18:2010
Level of participation: the number of sub-disciplines that an organization identifies within its scope, and therefore the number of specific proficiency tests
that should be considered for participation.
Frequency of participation: how often a laboratory determines that it needs to
participate in PT for a given sub-discipline; this may vary from sub-discipline
to sub-discipline within a laboratory and between laboratories with the same
sub-disciplines.
Sub-discipline: an area of technical competence defined by a minimum of one
measurement technique, property and product, which are related.
Evaluation of the results of interlaboratory comparison/proficiency testing
Test and calibrating laboratories should strive to participate as often as possible in
various ILC/PT, most of all because it is an incredibly important tool enabling the
external evaluation of the quality of reporting results. Moreover, it is also possible to
evaluate the reliability of the measuring procedures used. In each ILC/PT scheme, the
main objective of the laboratory is to perform measurements for the object (sample)
delivered by the provider, preferably under conditions typical to everyday practice in a
given laboratory. Results obtained in the laboratory are then compared to the reference
value assigned by the provider, and the evaluation of the laboratory performance
includes the use of a selected score that classifies the given result in relation to the
reference value.
Satisfactory result within the applied score: laboratory confirms its competencies in the scope of the measurements conducted.
Questionable/unsatisfactory result within the applied score: corrective action
should be applied (the laboratory should conduct a detailed analysis of the
measuring procedure used and the environmental conditions).
The main objective of participating in ILC/PT is to evaluate the performance of
a given laboratory by comparing the result obtained by a laboratory (X lab ) with the
reference value (X ref ) versus the accepted target range. As previously mentioned, the
evaluation criteria should be provided to the participants by the ILC/PT provider.
Thus, the laboratory can critically evaluate the statistical tools used by the organizer
to reject the extreme values, to determine the reference values and to specify the evaluation criteria. All this information should be placed in the report, together with the
results of the participating laboratories. That information is necessary for the critical
assessment of the results obtained and, if the need arises, for using criteria stemming from legislative requirements or agreed upon with a customer. It is extremely
important in view of the need to analyze the results of the comparisons (ILC/PT) by