Any errors present in the BindingDB dataset may be grouped into two broad categories. The first category, errors in the source document (typically a patent or scientific article), may result from experimental errors of various types, errors in the analysis of raw data, or clerical errors by authors and editors. Such errors are difficult for us to discover and hence correct, though they might be flagged as outliers in cases where the same protein-ligand affinity has been measured more than once. Because different measurement procedures can introduce different biases, it is likely that the measured relative affinities of a series of ligands for a given protein -i.e., ratios of Kds or IC50s -as measured by one method in one lab are more accurate than the affinities themselves. The second category results from clerical errors in curation or data management, mainly by BindingDB or ChEMBL. These appear most commonly as a factor of 1000 error resulting from miscuration of e.g., an IC50 value as nanomolar instead of micromolar or vice versa. Based on user feedback, the next most common error appears to be misidentification of a protein target. This usually occurs during curation of a patent or article with data on multiple targets and/or subtypes of a target.