Histograms of parameters derived from our best fits represented with the same colour scheme as in Fig. 7. For comparison, the parameters derived from the model of Hensley & Draine (2023) are shown by the dark blue squares. The two figures in the top row show two characteristic ratios of the polarised observations made with the Planck satellite: R_P/p and R_S/V. The measurements, including their uncertainties, made by Panopoulou et al. (2019) and Planck Collaboration XII (2020), are represented by the black horizontal lines. The two figures in the middle row show the dispersion of λ_max (left) and of the polarised extinction at 10 µm normalised to the optical (right) of our best fits. The measurements, including their uncertainties, made by Vaillancourt et al. (2020) and Telesco et al. (2022) combined to McMillan & Tapia (1977) are shown by the black horizontal lines. The bottom row figure shows the histogram of the extinction parameter R_V. The measurements made by Decleir et al. (2022), including their uncertainties, are shown by the black horizontal line.