THR=IRFi∑Hj(Dj+Eij)∑AkCjk×Fik{\displaystyle THR={\frac {IRF_{\text{i}}}{\sum _{H_{\text{j}}}\left(D_{\text{j}}+E_{\text{ij}}\right)\sum _{A_{\text{k}}}C_{\text{jk}}\times F_{\text{ik}}}}}
IRFi{\displaystyle {IRF_{\text{i}}}}
∑Hj(Dj+Eij)∑AkCjk×Fik{\displaystyle {\sum _{H_{\text{j}}}\left(D_{\text{j}}+E_{\text{ij}}\right)\sum _{A_{\text{k}}}C_{\text{jk}}\times F_{\text{ik}}}}