Comparison between slinefit results and input values for the sample of 270 mock spectra. In the top panels, we plotted the pull distributions. As a reference, we marked with a grey curve a Gaussian with a null mean and unity sigma. In the bottom panels, we plotted the relative change of the measured spectral quantities, with respect to their input values, as a function of the peak S/N of the lines. Black squares represent the median values of the relative change in bins of the S/N; error bars are the semi-interquartile range (SIQR). The line parameters are, starting clockwise from the top left figure: line centroid, EW, FWHM, and flux.