How to offer a reviewer to be co-author?

Question

I currently have a paper submitted to PNAS. We had two rounds of revisions, and following detailed suggestions from one reviewer, we have improved our proposed algorithm a lot: its complexity is now significantly lower, and the idea he suggested makes the overall method more robust in handling noisy signal.

I feel that this reviewer's contribution extend far beyond his original role, so much that I feel it would be ethically honest to have him as a co-author. To be crystal-clear: if he was not a reviewer, but a colleague with whom I had discussed this before submitting the paper, he would clearly be entitled to authorship, no question.

But… he is a reviewer, so I am wondering how (if at all) we should ask him to join as co-author. Right now, I am ready to submit the twice-revised manuscript, and I have no doubt that it will be accepted (second review was “minor revisions”). The options I can see are:

• In my cover letter for the revised manuscript, explain the situation to the editor and ask him if he could (with the reviewer's agreement) lift anonymity and allow the authors' list change.
• Wait for the manuscript to be formally approved, and only then write to the editor asking for the same thing.
• Do nothing, for example because it is frowned upon. This would pain me greatly, because the reviewer really contributed very significantly to the algorithm, and I believe he should be able to claim authorship for this contribution (if he sees it fit).

So, what are accepted practices? How should I handle this matter?

Answer 1

Seconding other comments and answers: surely no one would be offended if you tried to make such an offer...

However, as already noted, if your offer is made prior to final acceptance, it might be misinterpreted, as your trying to clinch acceptance.

And that possibility surely has to be systematically excluded, so a foresightful editor and/or journal would surely not want to set such a precedent. A journal would not want authors to (be able to) solicit reviewers as co-authors, since this would create a conflict-of-interest situation, and cast doubt on the general validity and impartiality of their refereeing process!

That is, while it would be weird and awkward to publicly state such a policy, I would anticipate that the journal/editor would object as a matter of principle, to putting the reviewer on as a co-author.

Sensible reviewers would also understand this situation, for similar reasons, and in advance would expect no reward beyond "job well done". Even the anonymity of the referee should be maintained, as a matter of principle. Thus, we do often find effusive thanks to "the anonymous referee"...

Answer 2

I'd ask the editor now, assuming the reviewer has clearly stated that the paper should be accepted (at least conditionally on certain changes). The worst case scenario is that the editor will suggest waiting, and even if that happens I don't think the editor will be upset or offended.

On the other hand, if the reviewer has made critical comments and hasn't specifically stated in the comments to authors whether the paper should be accepted, then I would wait until the conclusion of the reviewing process, just to avoid looking like you are trying to bias the outcome.

This doesn't sound like a plausible issue in your case, but I've experienced it once as a reviewer. I made a lot of critical but apparently useful comments on a paper, and the authors offered coauthorship when they submitted a major revision. I don't think they meant this to be manipulative, but I wondered whether one effect would be to remove a critic from the reviewing pool for their paper (in which case I might be replaced with someone more favorable).

Answer 3

I also have an experience of being asked to become a co-author by the authors of one paper I refereed. It wasn't a journal of the PNAS caliber, but it's a good specialized journal.

I don't know exactly when the authors asked the editor, but he asked me if it was ok to disclose my identity to the authors because they told the editor that they wanted to include me as a co-author. It seems that the editor was fine with accepting the manuscript (maybe with another round of external review with another fresh referee). But I suggested submitting a revised version as a joint-work to a different journal, and we did so in the end.

In any case, I'm not sure if the reviewer is expecting such a request. As a reviewer, if I can't recommend publication, I always try to improve the manuscript I am reviewing as much as possible within a reasonable timeframe and, if possible, make it potentially acceptable for the journal. This may include proving a stronger theorem than the main result given in the manuscript, repairing critical errors in a proof, and so on.

From my experience, this practice doesn't seem extremely uncommon in design theory (which is my expertise), and I have also benefitted greatly from excellent referees. So, I don't expect anything from the authors, and I do the same when reviewing manuscripts in different fields (although it's practically impossible in some fields I work in because editors want reviewers to carefully read a paper in a very short period of time).

But if you do want to include your reviewer as a co-author, I tend to think that you might want to ask the editor that after a final editorial decision is made for the reasons stated in other answers. And you shouldn't be surprised if the reviewer declines the offer. Probably he or she isn't expecting it; the referee most likely just got excited while reading your great results and a bit "carried away." Such an offer would be helpful if the reviewer is a student or postdoc on the job market, or is trying to get tenured though.

Answer 4

It seems to me that you could reasonably tell the editor now that (1) you think the reviewer's contributions warrant co-authorship, but (2) you realize that offering co-authorship to the reviewer before the review process is complete would improperly interfere with that process, and (3) you therefore ask the editor to wait until the review process is complete and only then forward your offer of co-authorship to the reviewer.