Distributions of σ_O III]/σ_⋆ and ${\overline{\sigma }}_{[\mathrm{O}\mathrm{I}\mathrm{I}\mathrm{I}]}$. Colour map showing the average σ_O III]/σ_⋆ values for (a) peaked and (b) non-peaked sources in the low redshift (0.02 < z < 0.4) sample, in bins of L_1.4 GHz and L_[O III], similar to Fig. 7a. (c) Cumulative distributions of the average [O III] velocity dispersions. Comparison for compact (< 3″) and extended (> 3″) sources according to FIRST sizes in the low redshift sample. We also plot the compact NPS sources for comparison. The inset plot shows the asymmetry distributions for the [O III] profiles with multiple kinematic components. (d) Cumulative distributions for low redshift PS and NPS sources that are compact in FIRST.