The central panel of each image shows an example of the L_X − L_UV relation for both XMM-XXL (black stars) and the model (blue dots), in which the choice of μ, α₀ and f_max is shown in the titles. The black and red solid lines are randomly drawn from the posterior distributions of normalization and slope for XMM-XXL and the model, respectively, with the median regression line thickened. The bottom panels show the residuals given by the difference of observed and mock log L_2 keV and the right panels show the related distributions. The errors on the model are show in the bottom right corner of the central panels.