Globular cluster age distribution in M 31 from Cabrera-Ziri et al. (in prep.), Usher et al. (2024), and Wang et al. (2021), with sample sizes of 136 GCs, 290 GCs, and 293 GCs, respectively. The ages in the sample of Wang et al. (2021) correspond to their determined old clusters (t_age > 1.5 Gyr). For further comparisons with previous GC age determinations in M 31, see Fig. 8 of Wang et al. (2021). The smooth lines show the distributions smoothed by the measurement uncertainties. These are computed through a summation over normal distributions with the respective ages as the means and their uncertainties as the standard deviations for Usher et al. (2024) and over log-normal distributions for the other two data sets. Note that for the logarithmic uncertainties, the visualization in linear space is skewed with respect to the peak.