Age–metallicity (τ([Fe/H])) relations for nearby APOGEE stars (orange line, Feuillet et al. 2018) and for RAVE-on stars (solid lines, this work). Blue lines are values derived from log(age) PDFs, red lines are values derived from the underlying age distributions obtained from inversion, and black lines are values derived from Minchev et al. (2013) chemical evolution models. Dotted lines show mean metallicity as a function of log(age) for the same data.