Effective and efficient polarity estimation in blogs based on sentence-level evidence

One of the core tasks in Opinion Mining consists of esti-mating the polarity of the opinionated documents found. In some scenarios (e.g. blogs), this estimation is severely af-fected by sentences that are off-topic or that simply do not express any opinion. In fact, the key sentiments in a blog post often appear in specific locations of the text. In this paper we propose several effective and robust polarity de-tection methods based on different sentence features. We show that we can successfully determine the polarity of doc-uments guided by a sentence-level analysis that takes into account topicality and the location in the blog post of the subjective sentences. Our experimental results show that some of our proposed variants are both highly effective and computationally-lightweight