Plot of Γ vs. v_C․IV. The orange circles and the yellow squares represent the HYPERION and non-HYPERION QSOs, respectively. For simplicity we report in the plot the mean values of v_C․IV (see Table 1), but the fit takes into account all the existing values of v_C․IV (see Section 3.2). The thick coloured errorbars represent the maximum deviation from the mean, while the thin black errorbars represent the mean error. The dashed blue line is the linear regression while the shaded region represents the combined 1σ error on the slope and normalization (see Table 5). This is valid for all the following plots.