Known (K) Sample
Definition
A sample with documented, verified provenance used as the reference in a comparison. The origin of a K sample is not in question; its role is to anchor the measurement.
- Role
- Reference sample in a comparison
- Provenance
- Documented and verified before use
- Notation
- K, paired against a questioned (Q) sample
- Function
- Anchors the measurement, not the item in question
Common questions
How is a K sample kept from contaminating the comparison?+
It is collected, packaged and stored separately from the questioned item, with its own chain of custody, so cross-contamination or mix-up can be ruled out during review.
Can more than one K sample be used for the same comparison?+
Yes, examiners often collect several K samples to capture natural variation in the source, for example multiple handwriting exemplars or several swabs from the same reference person.
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...
- Measurement Traceability
- The property of a measurement result whereby it can be related to a national or international measurement standard through an unbroken chain...
- 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...