Do you have to have PhD or employed in academia to publish a textbook? I am interested in publishing a statistics textbook (e.g. through Duxbery, Springer, etc.). I do not have PhD in Statistics, nor am I employed in university or college as an instructor/professor (but I have BS and MS in Statistics).

Do I have to have PhD and/or have career in academia to publish statistics textbook with those publishers?

Thank you,
No, there are never any degree requirements in academic publications.   

I am in the field of mathematics, and I have some colleagues who published academic books while in graduate school and even, in a few cases, as undergraduates.  There are also academic textbooks published by people who have no degrees whatsoever in that field.

It is possible that the editors and reviewers will look into your credentials and may apply a bit more scrutiny to someone without a terminal degree...but more scrutiny when it comes to textbook publishing is not necessarily a bad thing.  In any case, if the book really is good they'll be happy to publish it no matter who you are.