Estimation of Scale Accuracy and Precision: A Case History

The information on scale accuracy and precision that is derived from the weighing of known standards is often of limited use. For scales in which the operator must read the result, it is difficult to remove the bias introduced by his knowledge about the standard weight; he is likely to record the standard weight even if the scale is not exactly accurate. For scales with digital readout, the reading may be to the nearest 5, 10, or 20 g, say, for scales commonly used in a fuel fabrication plant. A 10 kg weight, say, will record 10.000 for a scale rounded to the nearest 5 grams even though the scale may be biased by as much as 2.5 grams in either direction.