Certainly we can all argue about the underlying structure of the analysis of the data. However, I think that @tansey has done two great services here: 1.He's

Certainly we can all argue about the underlying structure of the analysis of the data. However, I think that @tansey has done two great services here: 1.He's proposed a full service taxonomy with by proposing a name for the phenomenon SND. Which is much a much better choice than JTS - Jumping the Shark or otherwise. 2. He's asking how we can evaluate that phenomenon. Proposing one solution. So the question becomes, how else can we evaluate the phenomenon and what can we do to reduce SND? Well having spent time elsewhere, here are a number of clear indicators of SND: 1. Shorter, less thoughtful responses, often veering into humor or the absurd. With chuckles getting the most upvotes 2. Less fact checking and less source linking in both posts and comments 3. More image / pic posting 4. Linkjacking, with materials not linked to the original materials. 5. More community centered posts aka AMA etc. 6. Fewer news links. So perhaps simply evaluating the length of comments of that same 1.8M HN data could support PG allegations. The next question is what can be done to prevent SND? I think that would be clear: Don't support the characteristics that lead to the decline.