Ratio between the IR (provided by CIGALE) and observed FUV luminosities, IRX (y-axis) versus the UV slope β (x-axis). The colours of the individual points represent the value of the parameter indicated to the right of the colourbar. From the top-left corner to the bottom-right corner the parameters presented here are: log M_⋆, log SFR, log  ⟨ SFR ⟩ ₁₀₀ (averaged over 100 Myr), D4000 index, A_V, A_FUV, α, δ, and log  ⟨ Age ⟩ _mass. Blue points indicate a low value and red points a high value. The dashed lines represent the IRX-β relations of Kong et al. (2004) in blue, and the Meurer et al. (1999) and Lyman-break analogue relations (green and red) that have been derived by Overzier et al. (2011). The median 1-σ uncertainty is displayed on the left side of each plot. Finally, the solid black line represents the best fit for the entire sample, minus the discarded data points: IRX = log  [(10^{0.396(β + 2.046)} − 1)/0.373] .