There are many reasons why measuring brings some measurement uncertainty: What you measure, the instrument you measure with, who is measuring and the surroundings in which you measure are some of them.
Theory
Absolute Uncertainty
Absolute uncertainty is the number that you need to add and subtract to find the accuracy range.
Range of measurement (accuracy interval):
where
Formula
Relative Uncertainty
The relative uncertainty is a percentage, and the formula is as follows:
Example 1
The weight of a stamp is estimated to be
What is the interval for the measurement and what is the relative uncertainty?
The absolute uncertainty is . Therefore, the interval is
This returns the measurement interval
That means the relative uncertainty is
What Does Absolute and Relative Measurement Uncertainty Mean?
