Detecting speculative language using syntactic dependencies and logistic regression

  • Authors:
  • Andreas Vlachos;Mark Craven

  • Affiliations:
  • University of Wisconsin-Madison;University of Wisconsin-Madison

  • Venue:
  • CoNLL '10: Shared Task Proceedings of the Fourteenth Conference on Computational Natural Language Learning --- Shared Task
  • Year:
  • 2010

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Abstract

In this paper we describe our approach to the CoNLL-2010 shared task on detecting speculative language in biomedical text. We treat the detection of sentences containing uncertain information (Task1) as a token classification task since the existence or absence of cues determines the sentence label. We distinguish words that have speculative and non-speculative meaning by employing syntactic features as a proxy for their semantic content. In order to identify the scope of each cue (Task2), we learn a classifier that predicts whether each token of a sentence belongs to the scope of a given cue. The features in the classifier are based on the syntactic dependency path between the cue and the token. In both tasks, we use a Bayesian logistic regression classifier incorporating a sparsity-enforcing Laplace prior. Overall, the performance achieved is 85.21% F-score and 44.11% F-score in Task1 and Task2, respectively.