To measure the improvement in performance due to the refit, we employ the mean shift performance metrics developed in Boothroyd et al. with Parsley 1.3.0 as the baseline. The mean shift metric, described in Equation , measures how much the average error (relative to experiment) of a prediction changes when moving from one force field to another. In essence, it is the difference in unsigned errors between the refitted force field (Sage 2.0.0) and the reference force field (Parsley 1.3.0) for the physical property calculation for each molecule, averaged over the test set.