NGC 2548 as an example of the RV selection. The RVs of all the crossed-matched member stars in the cluster are plotted assuming a normal distribution. The light grey colour curves denote stars we discarded for further analysis (FLAG = 0), while the dark grey ones are the selected stars. The two vertical dashed lines mark the 2-σ selection criterion. The Monte Carlo model result of all the selected stars is illustrated with the blue Gaussian curve. Their mean RV value (V_rad, mean), the 1-σ RV dispersion (σV_rad), as well as the number of member stars before (N_star) and after the RV selection (N_star, RV), are shown in the legend.