A measurement result only has an informative capability when it is true. The magnitude of this area of truth and the dimensions of possibility that a measurement result is "correct" is dependent on two factors:

1. the number of measurement values
2. the measurement uncertainty u of the applied measurement instrument (refer to the Statistical evaluation, online).

 

To 1. One  measurement value is no  measurement value. Therefore a number of measurement values should be recorded at one measurement point and statistically evaluated.

The statistical evaluation for the measurement result M from the number of measurement values is made by:

 M = x ± s

x is the average value of the individual measurement values x1, x2, ... xn , whereby n is the number of measurement values.

                            x = (x1 + x2 + ... + xn) / n.

s   is the standard deviation. It is a measure for individual value scatter around the average value and is calculated according to the following formula: