Opinion mining is a problem in the field of information extraction that aims to automatically extract opinion expressions from product reviews. Also one of the goal of the opinion mining techniques is to determine the opinion direction of a review.
Generally there are two approaches for opinion mining: 1- document level and 2- feature level opinion mining.
- Document level
- Turney,2002 presented an approach to calculate the opinion orientation using the Web as a corpus. The input review is classified based on the average semantic orientation of all the phrases in the review. They have used PMI-IR technique to measure the semantic orientation of each phrase in the review.
- Dave et al.,2003 introduced a novel approach to classify reviews in Amazon.com using normalized term frequency in uni-gram, bi-gram and tri-gram.
- Feature level
- Zhuang et al., 2006 introduced a novel technique to classify movie reviews by extracting high frequency feature keywords.
- Liu, 2004 uses a statistical rule-based approach to extract high frequency feature words.