The population kurtosis function KURTOSIS_POP is primarily used to determine the characteristics of outliers in a given distribution.

NULL values in expr are ignored.

Returns NULL if all rows in the group have NULL expr values.

Returns 0 if there are one or two rows in expr.

For a given set of values, the result of population kurtosis (KURTOSIS_POP) and sample kurtosis (KURTOSIS_SAMP) are always deterministic. However, the values of KURTOSIS_POP and KURTOSIS_SAMP differ. As the number of values in the data set increases, the difference between the computed values of KURTOSIS_SAMP and KURTOSIS_POP decreases.