@Wendy C wrote:Mike, there are various types of editors and each is different. First step is for you to determine what kind of editing you need and state that at the start of your RFP.
Developmental editors help to organize content, assess structure, assist with clarity, cut what doesn't belong, help writers to elaborate in places that are weak, and so on.
Copyediting is more of a technical edit. A copyeditor checks grammar, punctuation, and the like, but a copyeditor also looks at formatting, does light fact checking, addresses usage issues, and so on.
Line editors focus on the language itself. They look at vocabulary, pacing, syntax, overuse of certain terms, consistency of voice, and so on.
And proofreaders are really the final stop in the life of the manuscript -- proofreaders give the book the final once-over to catch any lingering errors after all those other editors have looked it over.
@ @Wendy, an excellent explanion of what different editors do, but what would you call someone who does the "heavy" fact checking, like I sometimes do with astronomy texts? In my case, I sometimes have to rerun eleborate calculations just to be sure the authors' basic premises and/or assumptions are correct, so does this make me a fact checker, or an editor? Or perhaps a saviour of sorts? 
@wendy_writes wrote:Reinier - SAVIOR would cover it. 😉
And as Kat wrote ...
I should really remove the editing/proofreading "skill" from my profile, since I did not come up through the editing and/or proofreading ranks as did all of you.
I only got into fixing astronomy texts when I pointed out some gross errors of fact (and logic) in a post on a forum that caters to budding cosmologists and advanced amateur astronomers.
The moderators there asked me to look over some other posts they had trouble with, which in time, led to some posters contacting me directly to look over their work. So I'm really not an editor in the accepted sense; instead, I only pick holes in ill-considered, poorly thought out, and sometimes badly presented cosmological / astronomical arguments / hypotheses / theories / ideas for a hefty fee.
ETA- I also charge people even if I don't find errors in their work
@Kat C wrote:Heisenberg!!! 🙂
There are different levels of copyediting, and copyeditors can perform light, medium or heavy fact checking. The Copyeditor's Handbook gives a great explanation of this (page 12, 3rd Ed.). Also, yes, some publications may have a separate "fact checker" function.
Heisenberg; I love it more every time I see it
