What is the coefficient of variation?

In probability theory and mathematical statistics, coefficient of variation, also known as deviation coefficient, is a normalized measure of deviation degree of probability distribution, which is defined as the ratio of standard deviation to average value.

That is, when it is necessary to compare two groups of data with large or small deviation, if the measurement scales of the two groups of data are too different or the data dimensions are different, it is not appropriate to compare them directly with standard deviation. At this time, it is necessary to eliminate the influence of measurement scale and dimension, and the coefficient of variation can do this. The coefficient of variation is the ratio of the standard deviation of the original data to the average value of the original data.

Extended data

Application conditions of coefficient of variation:

When the absolute values of the two series compared are different (especially different), we can't compare and analyze with the standard deviation, because the standard deviation is an absolute index, and its value is not only affected by the difference of the sign values of each unit.

In order to compare and analyze the variation degree of marker values between variable sequences with different absolute values, it is necessary to eliminate the influence of absolute values and then calculate the coefficient of variation.

Meaning:

Reflect the dispersion degree of the observed values of each index on the unit mean, which is often used to compare the dispersion degree of two indicators with unequal overall mean or different dimensions. If the mean values of two populations are equal, the comparison standard deviation coefficient is equivalent to the comparison standard deviation coefficient.

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