Histograms of the redshift (top panel) and S/N (bottom panel) for quasars (left column in purple for the WEAVE mock catalog and in green for DESI EDR) and galaxies (right panel in blue for the VIPERS and in green for DESI EDR). The unfilled histograms show the distributions of the parent samples, while the filled histograms show the distributions of the final samples after all the data selections.