Sure, a meta-analysis of several studies reveals more than one single study, but that doesn't make a single study bad or worthless - or as said in the parent - "a bullshit study".
This was a pilot study, a way to open an avenue of discussion, and to be sure I think the study warrants more investigation. They even say so: "In future we would like to conduct larger studies over multiple countries."
Of course. Never said otherwise.
while you may not intend that, most people reading your comment would believe you think the study is fine
No. I was replying to the specific objections the parent poster had.
I never said or implied anything about whether I thought it was a good study or not.
In particular, the way in which you mentioned extrapolation in the context of the study (and the conversation in general) carried the implication that the extrapolation was valid.
This only really works if you have a representative subset of he population you're extrapolating to. Is the distribution of experience roughly equivalent to the general population of "developers"? Age distribution? Company size? # of children? Home life? These kinds of demographics can have a big impact, and I see no discussion of how they were accounted for.
Heck, even the general work ethic culture difference between the UK vs the rest of the world could be a huge confounding factor that I know wasn't really accounted for.