Goodness-of-fit plots for the final sublingual buprenorphine physiologically-based pharmacokinetic (PBPK) model, showing dose versus the ratio between predicted and observed (P/O ratio) (a) area under curve (AUC; i.e., AUC0–∞ and AUC0–τ for single and multiple dose studies, respectively), (b) apparent clearance (CL/F), (c) peak concentration (Cmax), and (d) time to reach Cmax (Tmax), as listed in Table 3 and 4. Sublingual tablet and solution doses are represented by diamonds (◆) and circles (●), respectively. In each panel, the solid black line represents the line of equality, where descending shades of blue filled areas represent 1.25-, 1.5-, and 2-fold prediction error ranges, respectively. Curved black dashed lines represent locally estimated scatterplot smoothing (LOESS) curves.