Otherwise we take the median of the multiple measurements. After this filtering, we remove any ligands that have binding affinity information for a PDBID that has no other ligands with binding affinity measurements. We then construct congeneric series by creating ordered pairs of ligands that have the same receptor structure and the same measure of potency (IC 50 , K d ,K i ). We utilize the log-converted measurements (-log 10 (value)), referred to as "pK", for each measure of potency. We next define a reference ligand. The reference ligand is assigned as the ligand with the highest Tanimoto similarity (using the RDKFingerprint from RDKit 21 ) to the ligand used for the template docking, usually the ligand in the crystal that was used for template docking. Our final filtered BindingDB dataset has 1082 congeneric series, encompassing 943 unique receptor structures with an average of 7.995 ligands per congeneric series. The average pK range of each congeneric series is 2.023 pK. Histograms of the number of ligands and the affinity ranges per congeneric series are shown in Figure .