A condition that is not the measurand itself but changes the reading an instrument gives for it. Ambient temperature acting on a steel part, supply voltage on a transducer, barometric pressure on a gas flow reading and lead resistance on an RTD are typical cases. Each significant influence quantity gets a correction, a line in the uncertainty budget, or usually both.
Humidity is an influence quantity on these capacitance standards, log it with every reading.
Also heard as
- influence factor
Related terms
Measurand
The exact quantity a measurement is aimed at, pinned down tightly enough that everyone measures the same thing.
Correction
The amount added to a raw reading to cancel a known, repeatable error, equal to that error with its sign flipped.
Reference temperature
The standard temperature at which a quantity is specified, 20 degrees C for dimensional measurements.
Uncertainty budget
A table listing every uncertainty source in a measurement with its size, distribution, divisor and contribution to the total.
Soak
Letting an instrument, artifact or part sit in the lab environment until it reaches thermal equilibrium.