Left: the relationship between Eddington fraction and black hole mass contrasting QSOs in our sub-mm sample (filled circles plotted with their 1σ errors) to the QSO samples of Shemmer et al. (2004, triangles) and Netzer et al. (2007, squares). Quantities for the latter two samples were recalculated using the scaling relations and cosmology used in this work, and smaller symbols are used for QSOs with redshifts  >2.5. The thin and thick arrows show the typical shift of the Shemmer et al. (2004) and Netzer et al. (2007) points, respectively, if the QSO black hole masses are calculated via the equations used by these authors. Right: as in the left panel, but only for QSOs in our sub-mm sample and in the case that only the very broad (VBLR) Hα component is used in the black hole mass estimation.