Redshift, colour, and magnitude properties of all samples used in this paper. Top panel: k + e-corrected (to z = 0) M_r used to define the luminosities relative to L₀, versus redshift z. Galaxies from MegaZ-LRG are shown in green, those from the SDSS LRG samples in blue, and galaxies from the red SDSS Main L4 (L3) sample in red (black). To avoid confusion, a subset of the points from each sample was used. Bottom panel: the colour-redshift relation. The colour coding is the same as above. As shown, the full MegaZ-LRG sample is the only one with significant contributions below ^0.2(g − i) = 1.7. Thus, we define the cut sample (pink points) using all MegaZ-LRG galaxies that are redder than this value, for consistency with the other samples.