Dispersion of the velocities V_R (left panels), V_φ (middle panels), V_Z (right panels) as a function of [Fe/H] (top panels), [α/Fe] (middle panels), and age (bottom panels) for the thin-disc, hαmp, and hαmr thick-disc populations (orange, blue, and magenta symbols, respectively). Solid lines represent velocity dispersions computed using chemistry and stellar ages from the APOKASC catalogue, while dotted lines represent velocity dispersions computed using abundances derived from DR16 APOGEE data (top and middle panels) and using stellar ages derived by M21 (bottom panels). Error bars on the velocity dispersions are also shown.