Seki et al, NTCIR 2006

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Overview of Opinion Analysis Pilot Task at NTCIR-6

paper slides


This paper presents an overview of the Opinion Analysis Pilot Task held at NTCIR-6 (2006-2007), which is a task-based evaluation task like TREC.

In the task, they analyzed and evaluated following four aspects.

Given a sentence,

  1. Does it express an opinion? - binary classification of opinionated sentence
  2. Is it positive, negative or neutral statement? - polarity analysis
  3. Who expresses the opinon? - opinion holder extraction
  4. Is it relevant to the document set topic? - binary classification of relevance between topic and sentence

Test collection

Language Corpus Topics Documents Sentences Opinionated Relevant
Chinese 1998-1999 United Daily News, China Times etc 32 843 11,907 62% / 25 % 39% / 16 %
Japanese 1998-1999 Yomiuri and Mainichi 30 490 15,279 29% / 22 % 64% / 49 %
English 1998-1999 Mainichi Daily News, Korea Times etc 28 439 8,528 30% / 7 % 69% / 37 %

The percentage opinionated and relevant are computed over sentences in both the lenient and strict standards based on the number of inter-annotater agreement.

Evaluation Metrics

Precision, Recall and F-Measure over opinionated, relevant and polarity. Semi-automatic evaluation of opinion holders (P, R, F)


For each Chinese, Japanese and English subtask, there were 5, 3 and 6 participants respectively. Performance across subtasks varies greatly. Considering the result of a system participated in multiple subtasks, there seems to be a strong relationship between quality of annotation (i.e. measured in inter-annotater agreement) and the system performance.

Next task in NTCIR-7

MOAT (Multilignual Opinion Analysis Task) at NTCIR-7 will start soon. Read Call For Participation for more detail. The registration due is Dec 27, 2007.

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