Various correlations with α_x. (a–d) Emission‐line parameters that correlate strongly with α_x. Open symbols are for radio‐loud quasars. The α_x versus Hβ FWHM correlation is the strongest in our sample. Note that the X‐ray–weak quasars do not stand out in these correlations; they thus have the "right" spectral slope but the "wrong" luminosity. (e) Note the trend of increasing α_ox with increasing α_x, which indicates that a steep α_x tends to be associated with a weak 2 keV flux rather than a strong 0.3 keV flux. The position of the X‐ray–weak quasars are marked. (f) The Y‐axis is a measure of L/L_Edd under some simplified assumptions, as described in § 4.7.