Page 41 - Pharmaceutical Analytical Chemistry III

Relative Standard Deviation (RSD) and
Coefficient of Variation (CV)

The relative standard deviation multiplied by 100% is called
the coefficient of variation (CV).

Relative standard deviations often give a clearer picture of
data quality than do absolute standard deviations.
As an example, suppose that a copper determination has a
standard deviation of 2 mg. If the sample has a mean value of
50 mg of copper, the CV for this sample is 4% [(2/50) ×
100%].
For a sample containing only 10 mg, the CV is 20%.