Using Natural Language Processing to Mine Multiple Perspectives from Social Media and Scientific Literature.

This thesis studies how Natural Language Processing techniques can be used to mine perspectives from textual data. The first part of the thesis focuses on analyzing the text exchanged by people who participate in discussions on social media sites. We particularly focus on threaded discussions that discuss ideological and political topics. The goal is to identify the different viewpoints that the discussants have with respect to the discussion topic. We use subjectivity and sentiment analysis techniques to identify the attitudes that the participants carry toward one another and toward the different aspects of the discussion topic. This involves identifying opinion expressions and their polarities, and identifying the targets of opinion. We use this information to represent discussions in one of two representations: discussant attitude vectors or signed attitude networks. We use data mining and network analysis techniques to analyze these representations to detect rifts in discussion groups and study how the discussants split into subgroups with contrasting opinions. In the second part of the thesis, we use linguistic analysis to mine scholars perspectives from scientific literature through the lens of citations. We analyze the text adjacent to reference anchors in scientific articles as a means to identify researchers' viewpoints toward previously published work. We propose methods for identifying, extracting, and cleaning citation text. We analyze this text to identify the purpose (author's intention) and polarity (author's sentiment) of citation. Finally, we present several applications that can benefit from this analysis such as generating multi-perspective summaries of scientific articles and predicting future prominence of publications.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/99934/1/amjbara_1.pd

Subgroup Detection in Ideological Discussions

The rapid and continuous growth of social networking sites has led to the emergence of many communities of communicating groups. Many of these groups discuss ideological and political topics. It is not uncommon that the participants in such discussions split into two or more subgroups. The members of each subgroup share the same opinion toward the discussion topic and are more likely to agree with members of the same subgroup and disagree with members from opposing subgroups. In this paper, we propose an unsupervised approach for automatically detecting discussant subgroups in online communities. We analyze the text exchanged between the participants of a discussion to identify the attitude they carry toward each other and towards the various aspects of the discussion topic. We use attitude predictions to construct an attitude vector for each discussant. We use clustering techniques to cluster these vectors and, hence, determine the subgroup membership of each participant. We compare our methods to text clustering and other baselines, and show that our method achieves promising results