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Fig. 6. Predicted vs. measured values of silt plus clay content for (A) the older Qf3 surface and (B) the younger Qf3 surface using GPR (ground penetrating radar) amplitudes and a categorical variable describing the degree of pavement development, outlier adjusted. For both figures, x1 = GPR amplitude and x2 and x3 are binary variables related to pavement development. Dotted lines are the predictive interval and dashed lines are the confidence interval, both at 95%.
