Both the upper and lower panels show the median residuals between the LSF model and selected 1D observations split into three equal percentiles of τ̇ - τ̇₀. The solid black line depicts the central third (33-66%), with the lower and upper thirds depicted by the dashed blue and dot-dashed green lines, respectively. In the upper panel, the LSF model is computed using the median value of τ̇ - τ̇₀ for the observations, whereas in the lower plot the LSF model is computed using the correct τ̇ - τ̇₀ for each observation.