Relation between the X-ray luminosity and duration of the plateau. We indicate Sample 1 and Sample 2 with black and blue points, respectively. Arrows show upper limits. Time is reported in the rest frame of the source. The black (red) dashed line is the best-fit line for Sample 1 (Sample 2) where the fitting function is log₁₀(L_X) = N + λlog₁₀(t_b). The orange dot-dashed line is the corresponding best fit for the union of Sample 1 and Sample 2. The light blue band indicates the 1σ region defined by the best-fit values found by Dainotti et al. (2010).