Examples of mock light curves, c(t), l(t), and ﹩{X}_{{\rm{obs}}}=c(t)+l(t)﹩, used for the analysis in Section 4.3. The top panel shows the HST 1367 Å light curve and the JAVELIN model used to generate the mock light curves, with the 1σ uncertainty shown by the gray band. The middle panel displays an example of a mock u-band light curve, with a large line lag and high fractional variability, likely to result in the largest change of the observed lag. The bottom panel shows an example of a mock R-band light curve, with a more realistic line lag and fractional variability, chosen to be consistent with the Hβ light curve. See Section 4.3 for further details.