 It is simply a measure of the outlier, 999 in this example.An upper bound for the sample kurtosis of "n" ("n" > 2) real numbers is
where formula_29 is the sample skewness formula_30.The variance of the sample kurtosis of a sample of size "n" from the normal distribution is

Stated differently, under the assumption that the underlying random variable formula_32 is normally distributed, it can be shown that formula_33.