Feature importance analysis for the IGM+z (blue), IGM-z (green) and NoIGM (yellow). For comparison, the stacked line profiles with its 1σ scatter is shown in grey. Each subplot shows the importance determining a different property. In top row, Δλ_True, EW_in, W_in from left to right. In the bottom row, N_H, V_exp, $f_{\text{esc}}^{4\stackrel{\circ }{\mathrm{A}}}$ from left to right. In each subplot we also show the z_max, W_g and Δλ_Pix importance for each model in its matching color in the small table.