Standard deviation is a similar measurement to variance. It is determined by calculating the square root of the variance and is defined as follows:

Remember that the variance squares the difference between all measurements and the mean. Because of this, the variance is not in the same units and the actual values. By using the square root of the variance, the standard deviation is in the same units as the values in the original dataset.

The standard deviation is calculated using the .std() method as is demonstrated here: