Top left: [Mg/Fe] as a function of [Fe/H] for the main sample. An example [Fe/H]-rich bin is shown in green (232 stars). Top-right: galactocentric radial velocity distribution for this bin with σ_meas = 49 km s^-1. Bottom left: distribution of errors on V_R. Bottom right: velocity dispersion distribution corresponding to 1000 bootstrap realisations, characterised by σ_e = 2 km s^-1. The intrinsic velocity dispersion derived by maximum likelihood is σ_R = 35 km s^-1.