Metrology

Precision

In metrology, we speak of precision to qualify the accuracy of the measurement. It accounts for random error(s).

It is estimated through repetitions of the measurement on the same or similar objects. The dispersion of the measurement results around the mean value qualifies this measurement precision.

Red dots represent the Zi measurements. These points are included in a zone: the fidelity. In the center of the red dots is the Z result (average value of the measurements).

Measurement precision is the deviation between indications or measured values obtained using repeated measurements of the same or similar objects under specified conditions:
For example, specified conditions can be repeatability conditions, intermediate precision conditions or reproducibility conditions.

Random error is a component of the measurement error which varies from one repeated measurement to another in an unpredictable manner.