Relations between IR luminosities and dense molecular line luminosities in logarithmic scale. (a): L_IR − L′_{HCN(4 − 3)}. (b): L_IR − L′_{HCO⁺(4 − 3)}. Detected data are shown as solid points, data points obtained from stacked spectra are shown as diamonds, and upper limits are marked by gray leftward arrows. The black circles highlight the central region of NGC 1068, which hosts the AGN. The Spearman rank correlation coefficients (ρ_sp) are displayed in each panel. The solid lines and their slopes (β) represent the best-fit results from Bayesian regression, as adopted from Tan et al. (2018).