Using Polarity Scores of Words for Sentence-level Opinion Extraction

The opinion analysis task is a pilot study task in NTCIR-6. It contains the challenges of opinion sentence extraction, opinion polarity judgment, opinion holder extraction and relevance sentence extraction. The three former are new tasks, and the latter is proven to be tough in TREC. In this paper, we introduce our system for analyzing opinionated information. Several formulae are proposed to decide the opinion polarities and strengths of words from composed characters and then further to process opinion sentences. The negation operators are also taken into consideration in opinion polarity judgment, and the opinion operators are used as clues to find the locations of opinion holders. The performance of the opinion extraction and polarity judgment achieves the f-measure 0.383 under the lenient metric and 0.180 under the strict metric, which is the second best of all participants.