The well-studied supervised Relation Extraction algorithms require training data that is accurate and has good coverage. To obtain such a gold standard, the common practice is to do independent double annotation followed by adjudication. This takes significantly more human effort than annotation done by a single annotator. We do a detailed analysis on a snapshot of the ACE 2005 annotation files to understand the differences between single-pass annotation and the more expensive nearly three-pass process, and then propose an algorithm that learns from the much cheaper single-pass annotation and achieves a performance on a par with the extractor trained.
