CDFs of the largest effective (left panel) and median (right panel) Einstein radius, assuming a redshift interval of 0.5 ≤ z ≤ 1.0, a source redshift of z_s = 2.5 and the nominal MACS survey area (upper panels) as well as the full sky (lower panels). Both distributions are based on the Tinker et al. (2008) mass function and the simulation of 1000 maxima with M_lim = 2×10¹⁴ M_⊙ / h on the full sky. The dashed-dotted lines, together with the yellow shaded area, illustrate the impact of the uncertainty in the WMAP7 value of σ₈ on the CDFs and the grey shaded area denotes the uncertainty in the measurement of the Einstein radius.