Bias
\(\text{PE}\ (\%)=\ \frac{{C_{\text{pred}}}_{i}-{C_{\text{obs}}}_{i}}{{C_{\text{obs}}}_{i}}\times 100\%\)(1)
\(\text{MDPE}\ \left(\%\right)=\text{median}\ (\text{PE}_{\text{ij}},j=1,N_{i})\ \)(2)