Tumblr is a weird social network.

Like Twitter its content is (very largely) public, and yet like Facebook it’s opaque to social analysis. Follower counts aren’t public or accessible. Ditto who’s following each blog (you can’t even really see all your own followers), and you don’t know who’s following anyone else either. Tumblr Analytics does exist, but not for ordinary users — instead you have to pay Tumblr partner Union Metrics $499 per month and what you get appears to be top-level and aggregate.

This leaves Tumblr a kind of “here be dragons” among social networks, which is unusual in an age so obsessed with them. That is, its social norms are not known; there isn’t any data about how its users behave and use the network (even for most Union Metrics subscribers there are no benchmarks). Rumours spread — Tumblr’s young, it’s photo-y and meme-driven, it’s full of weird tightly-interknit subcultures who reblog each other endlessly — but there is no data to support this, no way of discerning fact from — at best — intuition about one’s little own corner of the thing.