Finally, we observe that although α never corresponds to the variance-only case, its true value can easily be obtained from a small test set, and subsequently be used to transform between the model uncertainty (committee standard deviation) and the prediction error. Fig. depicts how α is fitted from 20 % of the test data of the SrTiO 3 system, which is then subsequently used to obtain the predicted error for the remaining 80 % of the test data, Fig. . The predicted error is simply αs i , and can approximate the true error up to a mean absolute deviation of only 0.005 eV Å-1 for each single data point(for a model with a force mean absolute error of 0.042 eV Å-1 ), thus providing an accurate, quantitative proxy of the error without the need for a separate calibration step. This enables an easy and reliable identification of erroneous model predictions for single data points, as opposed to a full dataset. In the Supporting Information, we furthermore report predicted errors for the Transition1x dataset resolved per NEB index.