Even not fully realizing this (see my replay to @tofflos) I did not exclude such a possibility and that's why I performed the Granger causality test for both hypotheses (SO influencing HN and HN influencing SO).
> But I'm puzzled by the framing. If I were looking at the relationship, I'd be asking questions like: Is HN a good place to post if I want to make something popular? If I learn about something on HN, is it likely to become popular? If I want to know what the next big thing is, is HN an indicator of that?
I guess these are different questions which are not covered by my analysis.
> If I'm thinking of SO as the cause of something, it'd be mainly in the category of docs: a supporting factor. So I'd be inclined to measure documentation and developer resources more generally.
To be honest, I do not understand this one. Could you please elaborate?