Comparison between [Fe/H] and [Mg/Fe] from HR and medium resolution spectroscopy, from Letarte et al. (2010) (HR), Battaglia et al. (2008) (CaT) and high S/N stars of Kirby et al. (2010) (Kirby) using overlapping stars. a) Comparison of the metallicity of HR spectroscopy with high S/N Kirby (red) and CaT (blue) stars, as a function of metallicity. b) The difference between medium resolution spectroscopic datasets of Kirby and CaT. c) Comparison between the [Mg/Fe] determined using HR and medium resolution spectroscopy.