Mean Absolute Deviation MAD(X={x1,x2,…,xn})=1n∑i=1n∣xi−xˉ∣\operatorname{MAD}\left(X=\left\{x_{1}, x_{2}, \ldots, x_{n}\right\}\right)=\frac{1}{n} \sum_{i=1}^{n}\left|x_{i}-\bar{x}\right|MAD(X={x1,x2,…,xn})=n1i=1∑n∣xi−xˉ∣ where xˉ=1n∑i=1nxi\bar{x}=\frac{1}{n} \sum_{i=1}^{n} x_{i}xˉ=n1∑i=1nxi, thus zi=xi−xˉ1n∑i=1n(xi−xˉ)2z_{i}=\frac{x_{i}-\bar{x}}{\sqrt{\frac{1}{n} \sum_{i=1}^{n}\left(x_{i}-\bar{x}\right)^{2}}}zi=n1∑i=1n(xi−xˉ)2xi−xˉ Median Absolut Deviation Robust against Outliers.