r² score, representing the goodness of match between XMM-XXL and mocks (see text), as a function of f_max. Models with μ = 0, 0.5, 1 are color coded in black, red and blue, respectively. The additional dependency on α₀ is represented with varying line-types as shown in the legend, when present (it is absent for μ = 0). A good match is represented with a score greater than zero. The points include the uncertainties in the score values. The shaded areas represent the results obtained applying the same methodology on a different sample (RM-QSO, Liu et al., in prep.), fixing α₀ = 0.02 and using the same colors.