Results of the cosmological fit for both sample 1 (green) and sample 2 (black) for a spatially flat ΛCDM with Ω_M and Ω_Λ free to vary. The correlation parameters γ and β (as well as the dispersion δ) of the X-ray to UV relation are also free to vary (see Section 6.2 for details). Contours are at 68% and 95% confidence levels. The input values of both the cosmological and correlation parameters are marked by the red square. All the input parameters considered to build the mock quasar samples are retrieved within the uncertainties.