To assess the quality of rank predictions, we measure the Kendall rank correlation coefficient between the PBE0-based ("true") rankings and the sampled ones. This coefficient assesses the difference in the proportions of correctly and incorrectly ordered pairs among all possible pairs in two sequences of observations, thus providing a general measure of the degree of similarity between the orderings. First we consider the correlations between the sampled (as above) and the "true" ranks for the top ranked series of structures: from the first 10 to the first 100 (Fig. ). We find that, while among the first 10 lower energy structures, on average, more than half of the pairs are ordered concordantly, this proportion decreases as the energy range increases (i.e. in the first 20 -30 ranked structures). However, the correct ranking improves again for the test structures with higher ener-gies. For all 158 test structures, across all 10 5 posterior samples, the (average) prediction ordering agrees with the PBE0-based one for 86% of pairs, and does not agree for 14%, leading to a median correlation coefficient of 0.72.