l____

Thank you. One of my personal goals with regard to this analysis was to learn Python on-the-go (I feel more comfortable in R) so I will definitely check pymc3.

I only reported plots I found interesting/saw some resemblance between HN and SO and in case of Rust probably none of those was he case. However, it must be said that I didn't have any quantitative criterion for this and this decision was purely subjective.

Hey, thank you for informative comments. I would gladly read more about hierarchical Bayesian regression. Would you recommend any sources from which I could learn more?

(I am fully aware that I can google it but in my opinion it's usually better to ask someone who is already familiar with the topic because he/she may know good learning materials.)

Hey, thanks for the comment. I am fully aware of that and did not stated otherwise in the analysis. I only established that there seems to be some kind of relationship but it is not possible to determine causality.

Thanks for pointing this out, I didn't think about this. Nevertheless, I assume that in an ideal situations when documentations for two programming languages have the same quality then the number of questions for the programming language which would have larger group of users would be greater therefore I still think of this measure as valid. I am also aware that we do not live in an ideal world.

Offtopic: I do not know how to measure and compare the quality of documentation and am curious whether there are any methods, so if you know some and could elaborate on this, I would be grateful.

Thanks! I wasn't aware that such a function exists.

Hey, I was thinking about writing something like that in the analysis. I finally decided not to do this because languages develop over time. I'm not a user of Java/HTML/Pascal/PHP but I use SQL quite frequently and in my opinion it is possible to ask a well defined question that did not appear before, at least for some "dialects" (if I name it correctly) like TSQL or Oracle SQL. Maybe if those "dialects" were investigated, their trends would not be downward.

> Yeah, I'm sure the causal arrow goes both ways.

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?

I was thinking rather otherwise, that is that people who use certain technology (technologies) would check posts about them on HN. Your point of view did not come to my mind so thanks for pointing this out.

Hey, thanks for the comment. I am aware that "correlation is not causation" and did not stated otherwise. The correlations would not answer the original question about the causation and it seems like this analysis cannot cope with it. Swift example suggests that causes of popularity of a given technology could be found outside Stack Overflow. It is, however, not impossible for Stack Overflow itself to be one of the causes of popularity of posts on Hacker News.

Fair point , thank you for the feedback. As I wrote, I did not detect causation (except for a couple of examples in which the null hypothesis of Granger causality test was rejected). The aim of the analysis was to find relationships between data from Hacker News and Stack Overflow without verification of other data sources , which could influence both websites.

Nor did I say I had found causation neither did write that I had not. I specifically stated that I tested the hypothesis of Granger causality which does not mean causality. Even if the main question of the article was causality, I could not answer it (and I stated this in the text).

Nevertheless, I agree that I should have probably been more careful with the term "causality" so thank you once again for pointing this out.