Question

Why does NIST classifies uncertainties in Type A and Type B instead of random and systematic uncertainties?

Answer 1

As, It should be noted that Type A and Type B uncertainties are not the same as“random” and “systematic” uncertainties. Random uncertainties vary for each measurement, yielding an observable “spread” in the data that will average to the conventional true value. Therefore, for a large number of measurements, theoretically there would be no uncertainty in the average value of the measured quantity. Systematic uncertainties are constant for each measurement, equal to the bias of the measurement technique, and are not observable in the data since the true value of the quantity being measured is unknown. Type A and Type B uncertainties involve analysis by the scientist.