Effective radius normalised to its local value, δr_e, as a function of redshift. The dott-dashed line is the observational evolution from van der Wel et al. (2008), δr_e = (1 + z)^-1.2. The solid line is the evolution due to major and minor mergers (μ ≥ 1/10) expected from our results. The shaded areas in both cases mark the 68% confidence interval. The dotted line is the expected evolution when the progenitor bias (PB) is taken into account. The dashed line is the expected evolution when PB and very minor mergers (μ < 1/10) are included (see text for details).