Comparisons between theoretical predictions and our radiative transfer modeling of the relationships between ϵ_ff, P_turb, t_dep, and I_HCN/I_CO. Left: Model efficiency per free-fall time as a function of turbulent pressure shown three ways: (1) using modeled I_CO and a fixed CO conversion factor for gas surface density estimates (colored points), (2) using the actual theoretical ϵ_ff and P_turb values (red line), and (3) using modeled I_CO with ⟨α_CO⟩ = 1/⟨ϵ_CO⟩ (purple trend line). The shaded regions represent the full range of model scatter. Estimates of these quantities from our sample of galaxies and the EMPIRE sample are shown as the solid black and dashed black contours, respectively. Right: Model depletion time as a function of HCN/CO ratio shown three ways, using the same approach. We find that the scatter produced by variations in CO emissivity can account for a significant portion of the scatter seen in observations. Additionally, the trend in ϵ_ff with P_turb is dependent on the assumed CO conversion factor. Pixel-by-pixel estimates of α_CO may be necessary for accurate studies of star formation trends. We note that the offset in ϵ_ff and t_dep between methods (2) and (3) is a result of the modeled CO emission missing a fraction of the lower surface density gas in our models, to CO-dark gas.