It all starts with a competent laboratory. Does accreditation guarantee
competence or consistency? How do you tell whether or not a laboratory
is competent?
This is the premise that underlies ISO/IEC 17025: General Requirements
for the Competence of Testing and Calibration Laboratories. The
accreditation process under this standard requires an unbiased accreditation
body to assess the laboratory’s quality system (section 4, which mirrors ISO
9001:2000) and the laboratory’s technical competence
The result of this accreditation audit is to identify the laboratory’s capabilities,
stated in their scope of accreditation
A scope of accreditation is a listing of each measurement parameter that the
lab can perform, indicating the lab’s Best Measurement Capability (BMC)
for each parameter. Bottom line: the ISO 17025 accreditation process
authenticates the laboratory’s measuring capabilities. It ensures that the lab
knows how to identify their uncertainty of measurement when performing
calibrations on your instruments
This measurement uncertainty is the validation portion of a calibration that
identifies whether or not the lab is capable of identifying the error in your
instrument. So,
generally speaking
, you can tell whether or not a lab is
competent by looking at their ISO 17025 certificate and scope of accreditation.
But, more importantly, you can
specifically
tell whether a lab is able to identify
the error in your instrument by comparing the tolerance of your instrument
to the lab’s measurement uncertainty for any reported reading. This
comparison is usually calculated as a ratio.