Posterior distribution over k(0), θ(0), k′(0), and θ′(0), based on selected Local Universe LoTSS DR1 RGs. We show all two-parameter marginals of the likelihood function, with contours enclosing 50% and 90% of total probability. We mark the MLE (grey dot) and the maximum a posteriori (MAP; grey cross). The one-parameter marginals again show the MLE (dash-dotted line), a mean-centred interval of standard deviation–sized half-width (hashed region), and a median-centred 90% credible interval (shaded region). We used flexible voxel method densities. For fixed voxel method densities, see Fig. D.2.