Cv is the coefficient of variation, which is the ratio of the sum of standard deviations to mathematical expectations, and cs is the coefficient of deviation, which is used to reflect whether the distribution is symmetrical.

Cv is the ratio of the sum of standard deviation and mathematical expectation, which is used to measure the relative dispersion of distribution. Cs is used to reflect whether the distribution is symmetrical or not, and it represents the degree of asymmetry of the distribution. Cv variation coefficient is also called deviation coefficient, cs deviation coefficient is also called skewness coefficient, cs >；; 0, called positive deviation, cs