Estimates of M_BH using corrected C IVλ1549 FWHM as a VBE versus M_BH computed from Hβ FWHM using the scaling law of Vestergaard & Peterson (2006). The luminosity and FWHM(C IVλ1549) data from Coatman et al. (2017) for Pop. A (blue) and B sources (red; see Sect. 5.5 for more details) are used to compute the C IVλ1549 M_BH according to Eq. (17). The dot-dashed line traces the 1:1 relation between M_BH from C IVλ1549 and Hβ; the black line is an unweighted least-squares fit for the A+B M_BH estimates.