Same as Fig. 5, showing the distributions of the valley parameters k and b (Eq. 1) for S-complex and C-complex asteroids. Over-plotted points indicate the best-fit valley solutions obtained from the dataset using progressively stricter spectral-classification score thresholds between 1 and 5 (as indicated by different symbols). Because the symbols lie within the distributions from the nominal datasets (see text), this illustrates the robustness of the fitted parameters versus changes in the spectral score threshold to the adopted spectral-quality cut.