Statistical Variance and Deviation Functions

Each of these functions takes a set of numbers, ignores nulls, and can be used as either an aggregate function or an analytic function. The relationships among these functions are described in the following table:

Function purpose Function name Formula Comments
Population variance VAR_POP(expr) (SUM(expr*expr) - SUM(expr)*SUM(expr) / COUNT(expr)) / COUNT(expr) Applied to an empty set, it returns null.
Population standard deviation STDDEV_POP(expr) Square root of the population variance (VAR_POP).

When VAR_POP returns null, STDDEV_POP returns null.
Sample variance VAR_SAMP(expr) *(SUM(expr*expr) - SUM(expr)SUM(expr) / COUNT(expr)) / (COUNT(expr)−1) Applied to an empty set, it returns null.
Applied to an input set of one element, VAR_SAMP returns null.
Sample standard deviation STDDEV_SAMP(expr) Square root of the sample variance (VAR_SAMP). Applied to only 1 row of input data, STDDEV_SAMP
returns null.