27. The coefficient of variation is the proportion that the standard deviation of the concentration of one of the substances in the medicinal premix or the medicinal food in each of the 9 samples of the premix or the food is of the average concentration of the substance in the 9 samples, expressed as a percentage and illustrated by the following formula: C.V. = S × 100
—
X
where C.V. = the coefficient of variation
S = the standard deviation of the concentration
and X = the average concentration.