A simple robust scale estimator is the interquartile range, which is the difference between the upper and lower quartiles. For a normal population, the standard deviation can be estimated by dividing ...

We discourage the use of a diagnostic for normality: the interquartile range divided by the standard deviation. This statistic has been suggested in several introductory statistics books as a method ...

The standard deviation is a formal measure of the tendency of the numbers in your list to vary – or deviate – from the mean. You can think of it as a measure of how "spread out" your numbers are.

Standard deviation Standard deviation is a measure of the spread of data around the mean value. It is used in comparisons of consistency between different data sets.