This group of DAX functions contains several aggregation functions that will help you to calculate the standard deviation and variance of a population. There are two variations of each function: one with a suffix of .P and the other with a suffix of .S. The functions that end with .P calculate the result using a formula that is based on the assumption that the data represents the entire population. Those ending with .S use a slightly different formula that is based on the assumption that the data represents a sample of the entire population.
As with the other functions in this group, there are also versions of the functions that work with a single column and versions that iterate over a table, evaluating an expression. Let's start by looking at the four functions that will help you to calculate standard deviation.