Impact of quality flags on the gspspec parameters. The data sets shown are the full (black), medium-quality (green), and best-quality (purple) samples. Top: Kiel diagram. Artifacts were progressively removed for more stringent selections. Middle: Calibrated metallicity distribution. The 16th, 50th, and 84th percentiles of each sample are shown in the colored text. The metal-poor tail was more heavily affected by the flags. Bottom: Distribution of surface gravity uncertainties. Only targets with small uncertainties survived the most stringent quality cuts.