Importance of observational and physical parameters for $f_{\text{esc}}^{\text{Ly}\alpha }$, EW_Lyα, and L_Lyα using the absolute value of Kendall’s τ (marginal perspective; Sect. 4.1.1). In each panel, the parameters are ranked according to |τ| from top to bottom. The length of each bar indicates the absolute value of τ and the error bars indicate the upper- and lower quartile from the robustness analysis presented in Appendix E. Each bar is coloured in red or blue depending on whether τ > 0 (correlated trend between parameter and response) or τ < 0 (anti-correlated trend between parameter and response), respectively. The vertical dashed red line indicates the threshold |τ|> 0.239, which corresponds to p_τ < 0.05 for N = 33 (Appendix E). The left, centre, and right panels show the results for the response EW_Lyα, $f_{\text{esc}}^{\text{Ly}\alpha }$, and L_Lyα, respectively, where the left and right subpanels show the rankings for the observational and physical parameters, respectively.