Distributions of D_n(4000) parameter in our samples: left panels include early-type galaxies according to their concentration parameter, while right panels include late-type galaxies in our samples. Panels a) and b) show all galaxies in the samples, panels c) and d) galaxies in groups with ETF ≥ 70%, and panels f) and g) galaxies in groups with ETF < 70%. All distributions have been normalised to have the same area. Below each panel, we show the residuals between the CGs and the other distributions. The binsize is 0.14. Based on KS tests, we find there is no pair of them drawn from the same underlying distribution. Line types are as in Fig. 1.