Strength of variability (flux standard deviation) with respect to rest-frame frequency as observed with EB and PV. Top: Scatter plot (black, all sources) showing increasing variations with frequency. Superimposed are shown the logarithmic sample averages of the standard deviation after binning in frequency space. Middle: logarithmic averages of the standard deviation obtained for the FSRQs (red) and BL Lacs (green) in the sample. Bottom: three examples of individual sources showing (i) a rising trend (blue); (ii) a clear peak (black); and (iii) a nearly flat trend of variability amplitude across our bandpass (red).