Standard deviation: It is the square root of mean/average of squared deviations of data point from mean i.e. we subtract the mean from each data point; take it's square value (which is again non-negative); sum it up and divide by the number of observations. Surely, standard deviation is a better & most commonly used measure of variation. For more details on the comparison between the two, please see Mean absolute deviation vs. standard deviation 19.5k Views · View Upvoters