With the growth of social media, document sentiment classification has become an active area of research in this decade. It can be viewed as a special case of topical classification applied only to subjective portions of a document (sources of sentiment). Hence, the key task in document sentiment classification is extracting subjectivity. Existing approaches to extract subjectivity rely heavily on linguistic resources such as sentiment lexicons and complex supervised patterns based on part-of-speech (POS) information. This makes the task of subjective feature extraction complex and resource dependent. In this work, we try to minimize the dependency on linguistic resources in sentiment classification. We propose a simple and statistical methodology called review summary (RSUMM) and use it in combination with well-known feature selection methods to extract subjectivity. Our experimental results on a movie review dataset prove the effectiveness of the proposed methodology.

Social media has become highly popular in recent years that people are expressing their views, thoughts about any product, movie through reviews. Reviews are having a great influence on people and decisions made by them. This has led researchers and market analyzers to analyze the opinions of users in reviews and model their preferences. Sometimes reviews are also scored in terms of satisfaction score on any product or movie by customer (ratings). These ratings usually vary on a scale from one to five (stars) or very bad to excellent. In this paper we address the problem of attributing a numerical score (one to five stars) to a review. We view it as a multi-label classification (supervised learning) problem and present two approaches, using Naïve Bayes (NB) and Support Vector Machines (SVM's). We focus more on feature representations of reviews widely used; problems associated with them and present solutions which address them.