Distribution of metallicity estimates as a function of age compared to its prior. Each panel shows the posterior metallicity for a random subset of stars in the direction of the Orion star formation using both a uniform and an age-dependent prior. The median estimates are indicated by the point density, and the prior is shown by the solid lines (mean, 1-, and 5-sigma intervals). We note that the prior rejects anything outside the model range (below −2 and above 0.2 dex). The rightmost panel corresponds to our prior.