1. "Atheists" and "Atheists using OK Cupid" might be quite different populations. For instance, the latter might be younger, geekier, richer, poorer, etc. 2. "

1. "Atheists" and "Atheists using OK Cupid" might be quite different populations. For instance, the latter might be younger, geekier, richer, poorer, etc. 2. "Atheists using OK Cupid" and "Atheists identifying themselves as such on OK Cupid" might be different. (I haven't used OKC, so I don't actually know, but surely you aren't required to state your (ir)religious position?) For instance, the latter might be more likely to regard atheism as important, which might (e.g.) correlate with having arrived at atheism by careful consideration of the available evidence and arguments, which might correlate with better grammar or at least more care over grammar. (Yeah, that's a lot of mights.) 3. Being better at grammar is not the same thing as using more accurate grammar in the things you write at OK Cupid. (You might be extra-careful or deliberately inaccurate; it would depend on what you expect your "audience" to like.) Nor is it the same as caring whether other people's bad grammar annoys you. And yes, all these things would apply to any group. For instance, I understand that there are Hindu-specific dating sites; so maybe Hindus on OK Cupid are, I dunno, likely to be less concerned about meeting other Hindus, which might mean that they tend to be more cosmopolitan, which might correlate with being better educated. Or something. Again, lots of mights. But you have to be really careful about extrapolating from this kind of thing to the population at large.