Figure 2. Values for observed concentrations (determined using NONMEM's post hoc step for the mixed-effects approach) divided by predicted concentrations at each sampling point are plotted against time. Values for each individual are connected. Predicted values were determined using the “optimal” model (see Results). If the model fit the data perfectly, all values would lie on the horizontal line at 1.0. The minimal deviations from this line suggests that the model fits the data well.