Histograms of jet ridge-line apparent width, dP, and width evolution, ΔP, for γ-ray detected variables sources (continuous black line), γ-ray detected non-variable sources (dashed black line), and γ-ray non-detected sources (gray blocks). Given the large difference in absolute numbers, we plot histograms normalized to surface area unity. We used data from Karouzos et al. (2011).