Left panels: the fraction of red galaxies according to their ^0.1(u − r) colour; centre panels: the fraction of early-type galaxies according to their concentration parameter; right panels: the fraction of red early-type galaxies. All fractions are shown as a function of absolute magnitude. The upper panels compare CGs, LGs of low and high mass, and field galaxies, while lower panels compare CGs and LGs with similar redshift and total absolute magnitude. Vertical error-bars are obtained by using the bootstrap resampling technique, horizontal error-bars are the 25% and 75% quartiles of the absolute magnitude distribution within each bin.