The factors investigated in this study were evaluated for their effect on hit enrichment across active learning cycles. This was quantified using the enrichment factor (EF) , which captures the ratio between the number of hits found among all acquired molecules and the number of hits expected in selecting the same number of molecules at random from the screening library. Enrichment factor values larger than 1 indicate methods that can enrich a selection of hits more than a random pick (the higher, the better), while enrichment factor values lower than 1 perform worse than random at hit retrieval.