Mean age deviation, ΔA, with respect to the seismic estimate (abundance-based minus seismic) when considering all the abundance indicators, as a function of T_eff, [Fe/H], and M. The quantity δA is a measure of the improvement brought about by using 2D or 3D instead of 1D relations (see Sect. 9.1). The thin- and thick-disc stars are shown as filled and open circles, respectively. The Sun is shown as an open triangle. The rightmost panels show the breakdown of the ΔA and δA values.