Mean value (x-axis) and normalized standard deviation (y-axis) of the ionization parameter (log₁₀(U)) and the metallicity (Z) PIM-PDFs for the MUSE-Wide, the UDF mosaic, and the UDF10 objects studied in this work. The blue points represent the distribution of star forming models (Gutkin et al. 2016) matching the observations, the purple points indicate AGN models (Feltre et al. 2016), the green points show models based on BPASS binaries (Xiao et al. 2018), and the yellow points represent models of BPASS single stars (Xiao et al. 2018). The solid histograms show the distribution of the individual parameters. The vertical dashed line in the right panel marks the solar metallicity Z_⊙ = 0.01524.