Distribution of the pulls (residual/uncertainty) for the six feature parameters in the case of spectra with an S/N of 15, a dispersion of 5 Å/pix, and a velocity separation of 5000 km s⁻¹. The solid black lines indicate the desired zero pull value, while the solid coloured lines indicate the means of the distributions, the values of which are shown in the top left corner of each panel. The dotted lines display the measured standard deviations.