While a negative ρ rank indicates a problem with ones uncertainties, having obtained a positive ρ rank it is not clear from the number itself whether one should be alarmed or satisfied. To account for some of these drawbacks, we introduce the simulated Spearman's rank correlation coefficient (ρ sim rank ), where errors are randomly drawn from the predicted uncertainties (assuming Gaussian errors) and the ρ sim rank is calculated based on the simulated errors. Doing this a number of times (typically 1,000) we obtain an expected mean for the ρ rank as well as a standard deviation. The value of ρ sim rank defines the value of ρ rank one should get for the predicted uncertainty distribution. Problems can be identified by a big discrepancy between the simulated and observed values.