Median (top row) and dispersion (bottom row) of the transverse velocity Vt_b as a function of z for different subsamples of the final model (red symbols) and data (blue symbols). Full circles are for the whole sample. Left panels: Early type stars ( < 4 and G_RP < 0.55) (open diamonds), giants ( < 4 and G_RP > = 0.55) (crosses). Right panels: Selection made on Galactocentric radii with R < 8 kpc (open square) and R > 9 kpc (x). Points where the number of stars is smaller than ten are considered as insignificant and are not presented.