A.1.11—Measurement uncertainty

Uncertainty describes the plausible range around a measurement because of instrument resolution, variation or method limits. It should travel with the value through interpretation.

Record resolution and repeat variation, use consistent units and avoid reporting more precision than the method supports. Compare differences with their uncertainty rather than only their central values.

A 10.0 ± 0.5 cm reading and a 10.3 ± 0.5 cm reading overlap strongly; the data do not justify a confident difference.

Uncertainty is not the same as an error or mistake, and repeating a biased method does not remove systematic uncertainty.