Explanation
The coefficient of variation measures the relative variability of data with respect to the mean. It represents a ratio of the standard deviation to the mean and can be a useful way to compare data series when means are different. It is sometimes called relative standard deviation (RSD).
In this contrived example, the standard deviation is calculated in column H with the STDEV.P function:
=STDEV.P(B5:F5)
Notice that the standard deviation is the same for all data series (1.414214) even though the means vary substantially. To calculate the coefficient of variation (CV), the formula in I5 is:
=H5/AVERAGE(B5:F5)
This formula divides the standard deviation in H5 by the mean of B5:F5, calculated with the AVERAGE function. The result is a decimal value, formatted with the percentage number format. The calculated CV values show variability with respect to the mean more clearly. In the first data series, the CV is nearly 50%. In the last data series, the CV is only .12%.
Related formulas
Standard deviation calculation
Basic average example
Conditional mode with criteria
Related functions
STDEV.P Function
The Excel STDEV.P function calculates the standard deviation for a sample set of data. STDEV.P calculates standard deviation using the "n" method, ignoring logical values and text.
STDEV.S Function
The Excel STDEV.S function calculates the standard deviation for a sample set of data. STDEV.S replaces the older STDEV function, with the same behavior.
AVERAGE Function
The Excel AVERAGE function calculates the average (arithmetic mean) of supplied numbers. AVERAGE can handle up to 255 individual arguments, which can include numbers, cell references, ranges, arrays, and constants.
