Empirical CDFs for the percentiles 10%, 50%, and 90% and for the [M/H] obtained with 1000 synthetic test observations. If the posteriors are well calibrated, the nominal coverage probability (the fraction of the probability volume), on the x-axis, will be equal to the coverage probability (the fraction of actual values in such a volume), on the y-axis, making the CDF diagonal (dashed black line). Our CDFs closely follow the diagonal, indicating that the posteriors are properly computed.