Richness-mass scaling (left-hand and right-hand panels) and residuals (observed minus expected) as a function of redshift (central panel). The solid line marks the mean regression line (of log M₂₀₀ on log n₂₀₀) fitted to the individual galaxy data, while the shading indicates the 68% uncertainty (highest posterior density interval). The right-hand panel combines clusters in stacks of eight clusters each, with the exception of the most massive point, composed of just six clusters. Masses are corrected for the negligible best-fit evolution. Points and approximated error bars are derived by adding errors summed in quadrature, as commonly done in the literature. The open point (Abell 1068) is not fitted and is out of scale in the central panel.