Comparison between predicted and observed values of the ratios ¹³CO (1 → 0)/H¹³CO⁺ (1 → 0), o-H₂S (1₁₀ → 1₀₁)/CS (2 → 1), and CS (2 → 1)/HCS⁺ (2 → 1). The left panels correspond to the post-processed simulations at 0.1 Myr while the right panels correspond to 1.0 Myr. On each panel, the median value for the turbulent (uniform) case is highlighted by the solid (dashed) line, the IQR is represented by the dark area and the full range (from minimum to maximum) is represented by the light-coloured area. The uniform and turbulent cases are coded in blue and red, respectively. TMC-1 points are represented by circles and B213 by triangles, and error bars are always plotted although in most cases they are smaller than the marker. The error bars correspond to the statistical errors from fitting the lines and do not include systematics (GEMS IV).