Best fit parameters vs. input parameters for the case of a 1 mCrab source observed for a 100 ks X-IFU observation. The parameters of the reflection component are computed by the model to the predicted value of the geometrical configuration in the lamp-post geometry (Dauser et al. 2016) and then left as a free parameter of the fit. Fifty spins are generated to sample the range 0–0.995, while the height of the X-ray source is drawn at each spin from a uniform distribution bounded between 3 and 10 R_g. The iron abundance A_Fe is set to 1. The simulations are performed in the so-called configuration 2 described in Sect. 3.2. Left: spin parameter. Middle: height of the compact source. Right: reflection fraction vs. fitted spin parameters. The errors are computed at the 90% confidence level for variation of one single parameter. As predicted by the model, R_f tends to increase with the black hole spin; the scattering at high spins is due to the height of the X-ray source being allowed to vary between each simulation run.