As in Fig. 3, but showing posteriors on the redshift-dependent hyperparameters that characterize the power-law continuum. Specifically, we show posteriors on the power-law slope (top), mixing fraction (middle), and the location below which the mass distribution is truncated (bottom). The posteriors on other parameters (e.g. the maximum black hole mass and high- or low-mass truncation scales) are uninformative and are not shown here.