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