I don't really understand how you can measure popularity without doing a census-like survey, reaching out to every developer possible in a coordinated effort.

I don't really understand how you can measure popularity without doing a census-like survey, reaching out to every developer possible in a coordinated effort. Awhile back, I took a statistics class that explained how polling everyone by calling everyone with a phone landline resulted in a misrepresented sample. The reason: not everyone has a phone landline. And those with phone landlines had a tendency to belong to specific demographics. So...if you survey everyone using Github, and not every developer uses Github, are you not prone to the same fallacy?