Probability density estimate for the black hole mass of 3C120 when fixing the delay τ to its posterior mean value of 27.4 days (grey histogram). The observed variance of the grey histogram is entirely due to the variance of the velocity dispersion as delay τ is fixed to its mean posterior value. The blue line corresponds to the Gaussian probability density M_bh = (6.7 ± 0.6) × 10⁷ M_⊙ reported in G+2012.