The above formula for skewness is referred to as the Fisher-Pearson coefficient of skewness. Many software programs actually compute the adjusted Fisher-Pearson coefficient of skewness

Sample Kurtosis Formula The kurtosis and excess kurtosis formulas above are for population kurtosis (when your data set includes the whole population). Very often, you don’t have data for the whole population and you need to estimate population kurtosis from a sample. When calculating sample kurtosis, you need to make a small adjustment to the kurtosis formula: Sample kurtosis formula