Black hole masses of the objects of the SDSS-FIRST cross-matched sample, represented in the [NII]-based diagram. Left panel: the color bar indicates M_BH in solar units. Right panel: gray dots represent the overall black-hole mass distribution as in the left panel; red triangles indicate SDSS sources with velocity dispersion mismeasurements; blue squares indicate sources with M_BH> 10^9.3 M_⊙ (not flagged σ mismeasurements) overestimating black-hole mass measurements