ABSTRACT
Experiments to determine the precision and systematic error of a measurement process must be based on an appropriate random sampling of the range of circumstances commonly met in practice. The experiments must be capable of being considered a random sample of the population to which the conclusions are to be applied. Measurements obtained in routine re-measurement of the differences between pairs of mass standards constitute realistic repetitions of the calibration procedure as do measurements for a single check standard. Laboratories are frequently encountered where the environment or techniques may induce weighing error. A good example is when two different observers are asked to assign state-of-the-art mass values to a 1-kg mass standard. The strength of a laboratory’s standard operating procedure being followed by every operator in the laboratory is highlighted by the example.
