- 中位数:${Q}_{\frac{1}{2}}(x)={\begin{cases}x_{\frac{n+1}{2}},&{n \mbox{ is odd}}\\(x_{\frac{n}{2}}+x_{{\frac{n}{2}}+1})/2,&{n \mbox{ is even}}\end{cases}}$
- 中位数:${Q}_{\frac{1}{2}}(x)=\{\begin{matrix} x_{\frac{n+1}{2}} &{n \mbox{ is odd}} \\ (x_{\frac{n}{2}}+x_{{\frac{n}{2}}+1})/2 &{n \mbox{ is even}}\end{matrix}$