Probability density functions of mass-weighted LOS velocity dispersions for all simulations. Each curve shows the distribution of dispersion values obtained from the different masked sky maps for a given simulation. Dashed curves correspond to the large-scale–forced TURB runs, while dotted curves denote the SN-driven simulations (SN series and TIGRESS-MHD4pc). The dot-dashed vertical line marks the median H I velocity dispersion, ${\sigma }_{50}=11.1_{-0.3}^{+0.9}{\mathrm{km}\mathrm{s}}^{-1}$, derived from the Monte Carlo sampling of the LOS velocities reported by S25 using the Reid et al. (2019) Galactic rotation model parameters in a volume spanning 70–500 pc around the Sun. The gray shaded vertical band represents the corresponding 25th–75th percentile range. Velocity dispersions were computed after applying a velocity threshold of |v_los| ≤ 30 km s⁻¹.