Distribution of EW [O III] of our and other literature samples, as a function of bolometric luminosity. Side panels show the probability density of the quantities represented in the plot. BAL J0945+2305 is shown as an open pentagon. All but one of our objects show low EW [O III] (< 30 Å), suggesting a non-edge-on line of sight. Generally, luminous high-redshift quasars tend to cluster around low EW [O III] values.