Skewness
是统计数据分布偏斜方向和程度的度量，是统计数据分布非对称程度的数字特征。
Formula
\begin{equation} \[\tilde {\mu }_{3} = \frac{\sum_{i}^{N}\left(X_{i}-\bar{X}\right)^{3}}{(N-1) * \sigma^{3}}\] \[\tilde {\mu }_{3} = skewness\] \[{N} = number\ of\ variables\ in\ the\ distribution\] \[X_{i} = random\ variable\] \[\bar{X} = mean\ of\ the\ distribution\] \[\sigma = standard\ deviation\] \end{equation}