Standard Deviation
In most analysis we perform, the standard deviation will be much more meaningful than variance.
Standard deviation is the most common measure of variability for a single dataset.
Standard deviation is the square root of variance. for both population and sample.
Coefficient of variation (cv)
Comparing Standard deviation between two datasets is meaningless. The necessity of coefficient of variation arises when you want to compare 2 or more datasets.
it is also known as relative standard deviation.
Variance gives results in square units while standard deviation gives original units. This is why standard deviation is the preferred measure of variability for professionals as its directly interpretable.
The coefficient of variation helps us compare the variability between two or more different datasets. the advantages of cv over standard deviation are:
- does not have a unit of measurement
- cv value is universal across datasets
- perfect for comparison between datasets