Income Distribution Within U.S. Religious Groups
pewforum.org
pewforum.org
This group (unaffiliated) includes atheists, agnostics and people who describe their religion as “nothing in particular.” This latter group can be further divided into “secular unaffiliated” and “religious unaffiliated.”
Yup. And some of us can even spell "atheists". :-)
(I think it's worth distinguishing between "atheists have better grammar" and "people who identify themselves as atheist on dating sites use better grammar there". It may well be that both are true, but from the second to the first is quite a leap.)
I think you're probably right that there is a difference between all atheists and those who identify themselves as such on a dating site, but I can't put my finger on why that would be. Is there also a difference between all hindus/muslims/etc and those identifying themselves as such?
In order to argue that these people are representative of their self-reported religious affiliation, you have to show that the "uses dating site" subset is representative of the whole.
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.