Systematic Error
An error that shifts every result in the same direction by a similar amount.
Unit
Various
In depth
Also called determinate error or bias, systematic error affects accuracy but not precision and cannot be reduced by repeating the measurement. It is detected by analysing a certified reference material and eliminated by calibration or by correcting the procedure.
Examples in the real world
An uncalibrated balance reading consistently high; an indicator whose end point differs from the equivalence point.