Total age uncertainties as a function of age (or more precisely, the mode of the age PDF), for stars in LRc01 (red) and LRa01 (blue). Known RC stars are plotted as stars, RGB stars as pentagons. The black lines indicate lines of constant fractional age uncertainties (from left to right: 50%, 30%, 20%, 10%). The histograms in the top and right panels show the distribution of ages and age uncertainties, respectively.