Is it correct to define uncertainty as "The distinction between the measurements with different instruments"?

Thanks :D

  • $\begingroup$ That isn’t what it means in quantum physics. $\endgroup$
    – G. Smith
    Aug 9, 2020 at 4:58
  • $\begingroup$ Are you talking about quantum Physics or instrumental error analysis? $\endgroup$
    – Tony Stark
    Aug 9, 2020 at 5:13
  • $\begingroup$ I'm talking about instrumental error analysis $\endgroup$ Aug 9, 2020 at 6:22

1 Answer 1


Uncertainty in the context of instrument error analysis usually describes the random component of measurements of the same workpiece done by the same instrument.

Let's consider as an example the task to measure the length of a piece to a "high" degree of accuracy. The measured value contains many different types of errors. Some errors are attributed to the workpiece itself (e.g. if the two faces are not plan parallel, ...) and some are due to the measurement device itself. The uncertainty of the instrument only considers the second type.

E.g., if we use a laser interferometer to measure the distance of the workpiece, we will have fluctuations of the laser power, the wavelength, the temperature of the air above the workpiece (affecting the refractive index), ... All these different errors contribute to the measured value. However, since we are unable/unwilling to control each and every contribution, we obtain different measurement values if we keep remeasuring the same workpiece several times. This type of uncertainty should be called precision. Although the instrument contains other components of uncertainty as well, most people mean precision if they use uncertainty in this context.


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