Various factors affecting the error between the actual input fraction of retrograde thick-disc stars in the N-body model, and the fraction returned by the fit. Upper left panel: fits with Eq. (20), using data from various axial distance intervals as indicated by the labels. Upper right panel: different variants of Eq. (20) are tested, using the data from the axial interval x/h_R = 2.8 − 3.2: compared to the nominal case (“model=1”), in “model=2” the latter term in Eq. (20) has been omitted, while for “model=3” the has been replaced with , to correct for the contamination of LOS-velocity dispersions by systematic velocities. The middle panels (notice the change in the y-axis range) show the effect of using an incorrect fraction for thick disc, illustrated in the corresponding panel in the lowermost row. In the left panel frame the shape of f_T is retained, but the contribution of the thick disc in the equatorial plane has been multiplied with a factor indicated by the labels. In the right panel frame, the f_T profile has been stretched/dilated in the vertical direction by the amount indicated by the labels. The dashed lines indicated the fit obtained using the f_T estimated from a photometric thin-thick disc decomposition to the simulation data.