PIHVI: Online Forum Posting Analysis with Interactive Hierarchical Visualisation

We introduce PIHVI: a novel interactive system for visualizing and exploring a large hierarchical text corpus of online forum postings. The main view of the visual interface shows a largescale scatter plot, created by flexible nonlinear dimensionality reduction based on text contents of the postings, and we couple it with a coloring optimized by a second dimensionality reduction to represent the forum hierarchy. We exploit the hierarchy to provide data-driven summaries of plot areas at multiple levels of detail, allowing the user to quickly see and compare both the content-based similarity of groups of posts and how near they arise in the forum hierarchy. A user can move between hierarchy levels, mark posts or spots of interest, filter posts by content similarity and by location within the hierarchy, and inspect post contents. Experiments show the interface can reveal hidden semantic relationships between postings that would be hard to find based on the known hierarchy alone. ACM Classification