MUC-5 evaluation metrics

The metrics used for the Fifth Message Understanding Conference (MUC-5) evaluation are a major update to those used for MUC-4 in 1992. The official MUC-5 metrics express error rates while the official MUC-4 metrics express performance in terms of recall and precision (used for MUC-5 only as "unofficial" metrics). This paper discusses the current metrics and the reasons for their adoption.