  We have reanalyzed in a consistent way existing reverberation data for 35
AGNs for the purpose of refining the black hole masses derived from these data.
We find that the precision (or random component of the error) of
reverberation-based black hole mass measurements is typically around 30%,
comparable to the precision attained in measurement of black hole masses in
quiescent galaxies by gas or stellar dynamical methods. As discussed in this
volume by Onken et al., we have established an absolute calibration for AGN
reverberation-based masses by assuming that AGNs and quiescent galaxies follow
an identical relationship between black hole mass and host-galaxy bulge
velocity dispersion. The scatter around this relationship implies that the
typical systematic uncertainties in reverberation-based black hole masses are
smaller than a factor of three. We present a preliminary version of a
mass-luminosity relationship that is much better defined than any previous
attempt. Scatter about the mass-luminosity relationship for these AGNs appears
to be real and could be correlated with either Eddington ratio or source
inclination.
