Glossary
The language of measurement.
Concise definitions aligned with the international vocabulary of metrology and laboratory practice.
22 of 22 terms
- Calibration
The operation that, under specified conditions, establishes a relation between the values indicated by a measuring instrument and the corresponding values realised by reference standards, with their uncertainties. Calibration does not itself adjust the instrument.
See also:Metrological traceabilityMeasurement uncertaintyAs-found / as-left
- Metrology
The science of measurement and its application, including all theoretical and practical aspects of measurement whatever the field or level of uncertainty.
See also:CalibrationMetrological traceability
- Metrological traceability
The property of a measurement result whereby it can be related to a reference through a documented, unbroken chain of calibrations, each contributing to the measurement uncertainty.
- CMC (Calibration and Measurement Capability)
The smallest uncertainty a laboratory can achieve within its accredited scope when performing a routine calibration of a near-ideal device. A CMC is a laboratory capability statement, not the accuracy of any particular instrument.
- Measurement uncertainty
A non-negative parameter characterising the dispersion of the values that could reasonably be attributed to the measurand. Usually reported as an expanded uncertainty with a stated coverage factor (commonly k = 2).
See also:CMC (Calibration and Measurement Capability)RepeatabilityDecision rule
- Accuracy
The closeness of agreement between a measured value and the true value of the measurand. A qualitative concept — it is not expressed as a number, although manufacturers often use the word for a specified maximum error.
See also:PrecisionCMC (Calibration and Measurement Capability)
- Precision
The closeness of agreement between repeated measurements of the same quantity under stated conditions. Precision says nothing about closeness to the true value.
See also:AccuracyRepeatabilityReproducibility
- Repeatability
Measurement precision under conditions that include the same procedure, operator, instrument, location and a short period of time.
See also:PrecisionReproducibility
- Reproducibility
Measurement precision under conditions that include different locations, operators or measuring systems, on the same or similar objects.
See also:RepeatabilityPrecision
- Temperature mapping
A documented study that places calibrated sensors throughout a storage or process space to characterise the temperature distribution over time, locate hot and cold spots and confirm that the space stays within its acceptance limits.
See also:Temperature excursionGDP (Good Distribution Practice)PQ (Performance Qualification)
- UKAS
The United Kingdom Accreditation Service — the UK's national accreditation body, which assesses laboratories against standards such as ISO/IEC 17025.
See also:ISO/IEC 17025CMC (Calibration and Measurement Capability)
- ISO/IEC 17025
The international standard for the competence of testing and calibration laboratories. It covers impartiality, personnel, equipment, metrological traceability, methods, uncertainty, reporting and management-system requirements.
See also:Metrological traceabilityCMC (Calibration and Measurement Capability)UKAS
- GDP (Good Distribution Practice)
The quality-system requirements for the wholesale distribution of medicinal products, including temperature control and monitoring during storage and transport.
See also:GMP (Good Manufacturing Practice)Temperature mapping
- GMP (Good Manufacturing Practice)
The regulated quality requirements for manufacturing medicinal products so that they are consistently produced and controlled to the required quality standards.
See also:GDP (Good Distribution Practice)IQ (Installation Qualification)OQ (Operational Qualification)PQ (Performance Qualification)
- IQ (Installation Qualification)
Documented verification that equipment or a system has been installed according to its specification and the manufacturer's recommendations.
See also:OQ (Operational Qualification)PQ (Performance Qualification)
- OQ (Operational Qualification)
Documented verification that installed equipment operates as intended across its anticipated operating ranges.
See also:IQ (Installation Qualification)PQ (Performance Qualification)
- PQ (Performance Qualification)
Documented verification that equipment or a system performs consistently under routine conditions of use — for a storage space, often demonstrated by a temperature mapping study.
See also:IQ (Installation Qualification)OQ (Operational Qualification)Temperature mapping
- OOT (Out of Trend)
A result that is within specification but does not follow the expected pattern of previous results, prompting investigation before it becomes out of specification.
See also:OOS (Out of Specification)
- OOS (Out of Specification)
A result that falls outside the established acceptance criteria or specification limits and requires a documented investigation.
- Temperature excursion
A period during which a monitored temperature is outside its acceptance limits; characterised by its magnitude and duration and assessed for product impact.
- Decision rule
A documented rule describing how measurement uncertainty is accounted for when stating conformity with a specification — for example simple acceptance, or guard banding that reduces the acceptance zone by the uncertainty.
See also:Measurement uncertaintyISO/IEC 17025
- As-found / as-left
As-found data are the instrument's readings before any adjustment; as-left data are the readings after adjustment. Both are needed to judge whether measurements made since the previous calibration were affected.
See also:Calibration