Measurement Traceability
Definition
The property of a measurement result whereby it can be related to a national or international measurement standard through an unbroken chain of calibrations, each with stated uncertainties.
- Definition
- Unbroken calibration chain to a national/international standard
- Requires
- Stated uncertainty at each calibration link
- Common context
- Analytical instrument and reference weight calibration
Common questions
Why does an unbroken chain matter more than a single accurate calibration?+
A calibration performed years ago against a national standard tells a court little if the instrument has since drifted, so accreditation bodies require documented, dated links from the working instrument all the way back to the standard, each carrying its own uncertainty.
How does traceability differ from accuracy?+
Accuracy describes how close a measurement is to the true value, while traceability describes the documented pedigree connecting that measurement to a recognised standard, so a result can be traceable and still carry a large stated uncertainty.
Related terms
- Certified Reference Material (CRM)
- A sample with one or more analyte concentrations established by an accredited body and traceable to a national metrology institute. NIST SRM...
- Known (K) Sample
- A sample with documented, verified provenance used as the reference in a comparison. The origin of a K sample is not in...
- Negative Control (Blank)
- A sample known to contain no target analyte, processed alongside casework samples. Confirms that background contamination is not producing false signals in...
- Positive Control
- A sample of known composition containing the target antigen at a concentration that should produce a defined signal. Run alongside case samples...
- Questioned (Q) Sample
- A sample recovered from a scene, a person, or an object whose origin or relationship to a source is the subject of...