One thing that bugs me is how comments are linked to "interest". There are many topics that interest people (passive consumption), that do not necessarily translate into engaging in a conversation with others publicly.
As a marketing term - sure, that would be a good indicator of interest. Since this article is more scientific than marketing-oriented, I would clarify what some of the metrics mean (or don't mean).
You're right. A more ambitious thing might get a bit closer to people's "real interests" would be to follow posted links and topic model the contents of those links.
As a marketing term - sure, that would be a good indicator of interest. Since this article is more scientific than marketing-oriented, I would clarify what some of the metrics mean (or don't mean).
Excellent, fantastic visualizations though!