Fall relation for galaxies in the field (black squares) and those in rich groups with more than ten members (red circles). A stellar mass cut M_⋆ < 10¹⁰ M_⊙ and a redshift cut 0.5 < z < 0.9 were applied to each sub-sample. Outliers detected during the fitting process are identified with yellow stars and the typical uncertainty is shown with a black error-bar. The best-fit lines are shown for the field (black) and groups’ (red) sub-samples, along with their 95% confidence intervals (coloured areas) determined with jackknife resampling. Galaxies removed by the mass and redshift cuts are identified with semi-transparent symbols.