Relative standard uncertainty
Relative uncertainty uses a nonzero measured magnitude.
Key knowledge
Relative standard uncertainty is standard uncertainty divided by the absolute measured quantity value. For y≠0, u_r=u(y)/|y|; its percentage form is100u_r%. Near zero, relative uncertainty can become arbitrarily large while absolute uncertainty remains finite. The scale’s zero must have the intended meaning: an offset temperature conversion changes relative ratios even when the same temperature is represented.
Values and equations
u_r=u(y)/|y|, y≠0; percentage=100u_r%
- u_r
- Relative standard uncertainty 1
- u(y)
- Standard uncertainty of y chosen quantity unit
- y
- Nonzero measured quantity value chosen quantity unit
- percentage
- Relative standard uncertainty expressed per hundred %
Conditions and scope
- The numerator is a standard uncertainty with the same units as y, not an expanded uncertainty or a maximum error.
- The ratio is undefined at y=0. For logarithmic, ordinal or offset scales, state the scale and interpret whether a relative ratio serves the measurement purpose.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read VIM2.32 absolute-value quotient definition. The zero-domain, near-zero behavior and scale-offset caveats are disclosed algebraic consequences plus the already verified unit-conversion record, not additional VIM claims.
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Entry details
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- foundation-measurement-relative-standard-uncertainty
- Revision
- foundations-refresh.1
- Structured reference record
- Foundational reference additions