Comparison between the structure function and wavelet results for the comparison sample (black dots) and the S4 0954+65 light curves. In the left panel, the source’s timescales estimated up to February 2008 (cyan squares); in the right panel, the timescales from March 2008 to December 2009 (green squares). The black, cyan, and green lines show the results of applying linear regressions to the respective datasets.