\(\begin{equation} \label{eq:2} z=\left\{\begin{array}{cc} \frac{s-1}{\sqrt{\operatorname{Var}(s)}} & s \succ 0 \\ 0 & s=0 \\ \frac{s+1}{\sqrt{\operatorname{Var}(s)}} & s \prec 0 \end{array}\right. \end{equation}\)