The coefficient of variation (CV) is a relative measure of variability. It shows how large the standard deviation is in relation to the mean, and is useful when comparing variation between different datasets or units.

Formula:

CV=Standard deviationMean×100%\text{CV} = \frac{\text{Standard deviation}}{\text{Mean}} \times 100\% CV=MeanStandard deviation​×100%

Example:
Data: 10, 15, 20
Mean = (10+15+20)/3 = 15
Standard deviation (approx) = 4.08
CV = (4.08 / 15) × 100 ≈ 27.2%

This means the spread (variation) of the numbers is about 27.2% of their average.