A component of error that repeats in the same direction under the same conditions, such as a thermometer that always reads 0.4 °C high or a fixture that adds its own deflection to every reading. Averaging more readings does nothing to reduce it. Once estimated, a systematic error is removed with a correction, and the uncertainty of that correction stays in the budget.
Every reading on station 3 is high by the same 2 microns, that's systematic error, probably the probe tip.
Also heard as
- systematic effect
Do not mix it up with
- Random error: Random error scatters unpredictably and averages down; systematic error repeats and only a correction removes it.
Related terms
Bias
The estimated systematic offset of a measuring system: its average reading minus the reference value.
Random error
Error component that scatters readings up and down without pattern, so no two repeat readings agree exactly.
Correction
The amount added to a raw reading to cancel a known, repeatable error, equal to that error with its sign flipped.
Error
The signed difference between a measured value and the reference value of the quantity being measured.