(a) Ratio of measured k_bol values to expected k_bol values from D20 as a function of Log(L_bol). WISSH QSOs are compared to literature samples; the symbols are the same as in Figure 5. The two black dashed lines correspond to the 0.26 dex spread of D20 best fit to Type 1 sources. (b) Distribution of WISSH QSOs k_bol with respect to the D20 relation, including its spread (black horizontal dashed lines), i.e. being below, within, or above it. BAL and non-BAL sources are represented as indigo and purple bars, respectively.