7. Interactional Coherence Analysis

Despite the rapid growth of text-based computer-mediated communication (CMC), its limitations have rendered the media highly incoherent. The lack of coherence in CMC poses problems for content analysis of online discourse archives. Interactional coherence analysis (ICA) attempts to accurately identify and construct interaction networks of CMC messages. Although significant progress has been made, ICA research still has several limitations. Most previous ICA approaches used either system or linguistic features, but not both in conjunction, and also failed to address noise issues such as typos, misspellings, and idiosyncratic system usage behavior. Moreover, Web forums have seldom been studied for interactional coherence in spite of their prevalence. In this study, we propose the Hybrid Interactional Coherence (HIC) algorithm for identification of Web forum interaction. HIC utilizes both system features, such as header information and quotations, and linguistic features, such as direct address and lexical relation. Furthermore, several similarity-based methods, including a Lexical Match Algorithm (LMA) and a sliding window method, are utilized to account for interactional idiosyncrasies. Experiments were conducted on a large domestic extremist Web forum to compare the algorithm with traditional linkage and similarity-based methods. HIC significantly outperformed both comparison techniques in terms of precision, recall, and F-measure at both the forum and thread levels. The results demonstrate the effectiveness of HIC for identifying Web forum interaction.