Residual of the computational results of the probability of observing BALs (simulations) subtracted from the prevalence ratio (observational data). The four adopted values of the metallicities of 1, 2.5, 5, and 10 are represented in blue, red, magenta, and green. The solid black line is depicted as a reference for the observational data. The solid, dashed, dash-dotted, and dotted lines correspond to opening angles of the torus of 45, 60, 75, and 90 (no torus), respectively. The results are presented as a function of Eddington ratio (in steps of 0.3 dex) for three M_• ranges.