  We explored a method to reconstruct the distribution function of the Galactic
thick disc within the action space where nearby thick-disc stars are
distributed. By applying this method to 127 chemically-selected thick-disc
stars in the Solar neighbourhood, we found that the vertical velocity
dispersion that corresponds to the reconstructed distribution function declines
approximately as $\exp (-R/R_s)$ at 4.5 kpc < R < 9.5 kpc, with $R_s$ = 8.3
$\pm$ 1.1 (rand.) $\pm$ 1.6 (sys.) kpc. Also, we found that the vertical
velocity dispersion $\sigma_z$ of our local thick-disc stars shows only weak
dependency on radial and azimuthal velocities $(v_R, v_\phi)$. We discuss
possible implications of these results on the global structure of the Milky Way
thick disc.
