To address quality
assurance issues, there are two sets of numbers of interest.
The tolerance of
a measure is the difference between two measures that is accepted as reasonable
accuracy. The tolerance of a measure is generally larger than the degree
of refinement of a measure. For example, the weight of an infant is recorded
as 3.12 kg and on re-measuring it is recorded as 3.13 kg. These measures
are within an acceptable tolerance. If, however, the infant was weighed
at 3.12 kg and a second measure was 3.2 kg, the infant should be re-weighed.
If the third measure was recorded as 3.11 kg, the average of the two closest
measures would be recorded.