Named Entities in Medical Case Reports: Corpus and Experiments
Table 4: Annotated relations between entities. Relations appear within a sentence (intra-sentential) or across sentences (inter-sentential)
['Type of Relation case has condition', 'Intra-sentential 28', 'Intra-sentential 18.1%', 'Inter-sentential 127', 'Inter-sentential 81.9%', 'Total 155', 'Total 4.0%']
Entities can appear in a discontinuous way. We model this as a relation between two spans which we call “discontinuous” (cf. Especially findings often appear as discontinuous entities, we found 543 discontinuous finding relations. The numbers for conditions and factors are lower with seven and two, respectively. Entities can also be nested within one another. This happens either when the span of one annotation is completely embedded in the span of another annotation (fully-nested; cf. when there is a partial overlapping between the spans of two different entities (partially-nested; cf. There is a high number of inter-sentential relations in the corpus (cf. This can be explained by the fact that the case entity occurs early in each document; furthermore, it is related to finding and factor annotations that are distributed across different sentences. The most frequently annotated relation in our corpus is the has-relation between a case entity and the findings related to that case. This correlates with the high number of finding entities.