Degeneracy between the normalization of the average mass-loss rate, |$\bar{{\cal A}}$| and the scatter |$\:\sigma _{\log {\cal A}}$|⁠. Left-hand panel: the evolved SHMFs with different |$\:\sigma _{\log {\cal A}}$| (grey lines). The red line corresponds to our fiducial model (⁠|$\:\sigma _{\log {\cal A}}=0.17$|⁠) and is shown for comparison. Middle panel: the best-fitting |$\bar{{\cal A}}$| as a function of |$\:\sigma _{\log {\cal A}}$|⁠, for models with |$\:\sigma _{\log {\cal A}}$| indicated in the left-hand panel, and |$\bar{{\cal A}}$| adjusted to reproduce the fiducial, evolved SHMF. The dashed line indicates the least-squares polynomial fit to the degenerate sets of |$(\bar{{\cal A}}, \:\sigma _{\log {\cal A}})$|⁠, given by equation (C1), while vertical, dotted lines mark the scatter of our fiducial model, and that measured from numerical simulations by G08. Right-hand panel: fraction of subhaloes (in host haloes with M₀ ∼ 10^14.2 h^{− 1}M_⊙) that have an accretion redshift z_acc > 2.0 as a function of |$\:\sigma _{\log {\cal A}}$|⁠. The horizontal, blue dashed line indicates the fraction of such subhaloes in the Bolshoi simulation, with the shaded regions indicating the 68 and 95 confidence intervals (computing assuming Poisson statistics). Symbols correspond to our model predictions, and are consistent with the Bolshoi results (at 95 per cent CL) as long as |$\:\sigma _{\log {\cal A}}\lesssim 0.25$|⁠.