zELDA’s prediction of mean $f_{\text{esc}}^{4\stackrel{\circ }{\mathrm{A}}}$ for different mock Lyα line profiles using the IGM+z model. Each panel shows a different observation quality. The top and bottom rows display S/N_p=10.0 and S/N_p = 15.0, respectively. Each column has a constant W_g. In particular, we show W_g = 0.1 Å, 1.0 Å, and 2.0 Å from left to right. Four mean $f_{\text{esc}}^{4\stackrel{\circ }{\mathrm{A}}}$ z evolution scenarios are considered, which are shown as solid lines (green, red, blue, and grey). The true mean $f_{\text{esc}}^{4\stackrel{\circ }{\mathrm{A}}}$ in the mocks is shown as coloured squares. zELDA’s predictions for individual Lyα line profiles are marked as crosses. The mean $f_{\text{esc}}^{4\stackrel{\circ }{\mathrm{A}}}$ from zELDA’s prediction is shown in circles with its uncertainty.