[Mg/Ca]  versus [Fe/H]. Pal 4 and Pal 3 are taken from Koch & Côté (2010); Koch et al. (2009). The NGC 7006 data are from Kraft et al. (1998); the NGC 7492 data from Cohen & Meléndez (2005a); the M3 data from Cohen & Meléndez (2005b); the M 13 data from Cohen & Meléndez (2005b); dSph star data from Venn et al. (2004), Koch et al. (2008b), Shetrone et al. (2009), and Cohen & Huang (2009, 2010); and the MW disc and halo field star data from Johnson (2002), Cayrel et al. (2004), Venn et al. (2004), Sobeck et al. (2006), and Ishigaki et al. (2010). Corrections were applied to the literature data when Solar abundances differing from those of Asplund et al. (2009) were used in computing abundance ratios. The red error bar indicates the average random error in the abundance ratios of our target stars.