The processed data set was split into a training and a test set (Figure ). To support the comparability of this work with the previously published validation study on FAME 3, 3 we maintained the identical split of the training and test data. However, because of the refined data merging procedure described above, the numbers of compounds in the training and test data sets differ from those published for the FAME 3 validation study (Table ). atoms (where n is greater than or equal to 1) are selectively added to the active learning while all remaining ones serve as the data pool for later iterations of the selection process. The validation set was used to evaluate the performance of every generated model whereas the test set was utilized to evaluate the performance of selected models only.