Reference and conventional quantity values
An accepted comparison value need not be an exact true value.
Key knowledge
A reference quantity value is used as a basis for comparison with values of quantities of the same kind. A conventional quantity value is attributed by agreement for a given purpose. A reference can be a conventional value or another specified value with associated uncertainty. Agreement does not make a value an exact property of nature, and finite detail in a measurand definition can allow more than one value consistent with that definition.
Conditions and scope
- State the quantity kind, convention, reference provenance, purpose and any relevant uncertainty.
- Do not treat a historical conventional electrical-unit example as the current SI definition; a negligible-reference-uncertainty approximation needs justification for the comparison.
Sources · 3
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
- International Vocabulary of Metrology (VIM3)Joint Committee for Guides in Metrology (JCGM)Reference guideVIM3, entry 5.18VIM3, entry 2.12VIM3, entry 2.11
Evidence and review
Read VIM5.18 reference-value definition/notes,2.12 conventional-value definition/notes and2.11 true-value definition/finite-measurand-detail note. Exclude historical electrical conventional constants as current SI realizations.
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Entry details
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- foundation-measurement-reference-conventional-value
- Revision
- foundations-refresh.1
- Structured reference record
- Foundational reference additions