To find the coefficient of variation, use the following formula:
V=σ/Khsr, where
σ - standard deviation,
Khsr – the arithmetic mean of variational series.
Note that the coefficient of variation in practice is not only used for the comparative assessment of variations, but also to characterize the homogeneity of the population. If this figure is less than 0,333, or 33.3%, variation of the characteristic is considered weak, and if more 0,333 strong. In case of strong variations of the statistical population under review is considered to be heterogeneous, and the average value is atypical, so it cannot be used as a General indicator of the aggregate. The lower limit of the coefficient of variation is considered to be zero, there is no upper limit. However, with the increase in the variation of the characteristic increases and its value.
When calculating the coefficient of variation you have to use the standard deviation. It is defined as the square root of the variance, which in turn you can find as follows: D = Σ(X-Khsr)^2/N. in Other words the variance is the average squared deviation from the mean value. The standard deviation determines how much the average are rejected specific performance of the series from their mean value. It is an absolute measure of the oscillatory characteristic, and so clearly interpreted.
Consider the example of calculation of coefficient of variation. Consumption of raw materials per unit of output, produced by first technology is Khsr=10 kg, with an average standard deviation σ1=4, according to the second technology – Khsr=6 kg, with σ2= 3. When comparing the standard deviation it is possible to make a wrong conclusion that the variation of the consumption of raw materials at the first technology is more intense than the second. The coefficients of variation V1=0.4 or 40% and V2=0.5 or 50% make the opposite conclusion.