Measured coefficient a₂₁ normalised to the (rescaled) value from Calzetti et al. (2007) for H II regions as a function of several physical properties. Grey points are individual H II regions, while red hexagons represent the median values as a function of the quantity on the x-axis. In each panel we report the values of the Spearman rank correlation coefficient (and its error). The 16th–84th percentiles are shown as a red shaded area. The quantities considered on the x-axis are (a) equivalent width of Hα in emission, (b) sSFR surface density, defined as the ratio between the SFR surface density obtained from dust attenuation corrected Hα (assuming a fully sampled IMF) and the stellar mass surface density measured from MUSE data via spectral fitting (Σ_⋆), (c) Hα luminosity per unit area corrected for dust attenuation with the Balmer decrement (I_Hα, corr), (d) E(B − V) of the gas obtained from the Balmer decrement, (e) ratio of the luminosity per unit area in F2100W to that in F200M (I₂₁/I_2.0), (f) luminosity per unit area in F2100W, (g) MUSE stellar mass surface density from fits to the stellar population to optical spectra, (h) molecular gas surface density, derived from ALMA CO(2−1), (i) gas-phase metallicity, (j) ionisation parameter, (k) [S II]λλ6717,31/Hα ratio, and (l) [O I] λ6300/Hα ratio.