Journal rejects my conference-to-journal extension, saying it's copied from previous publication. What should I do? My understanding of short conference papers being extended to journals was that I should have at least 30% fresh results and content (read that in answers to this question here). I had a short 4-page paper published and presented as a poster at a conference in the past year. I had extended the work, had plenty of fresh results with me, and decided to send it to a journal. I would say I had at least 70-80% fresh content and results. 

I was surprised to receive a reply from the Editor that my manuscript was been rejected without review. The reason given by an editorial board member is 


  A non-negligible part of this manuscript (~1000 words) has been copied by a previous publication of these authors. 


And, thus, he suggested that the manuscript be rejected without review.

I agree that some basic data pre-processing modules are same in both papers (coz why would they differ!). Some introduction and related work part is also the same. Rest, the manuscript is fresh. My manuscript is easily 9000-10000 words. 1000 words just makes 10% of that. Keeping in mind that "30% fresh content" rule, I thought I was playing pretty safe. But this response has disappointed me :(

My  questions:


Should I bother to write to the Editor, asking for a clarification? Maybe I can just ask whether the editor bothered to read my cover letter (where I had clearly mentioned about the previous paper, and the overlaps with this paper).
If yes, how does one usually contact the Editor? The emails sent by the journal do not come from a personal account. Will it be wise to write to him directly?
After this rejection, I may submit it elsewhere. But what if it gets rejected on same grounds. Should I consider re-writing my manuscript and making it completely different from the previous paper?
So you wrote in the cover letter that the work is an extended version of a conference paper that accompanied a poster presentation.

Apparently, this information got missing somewhere. Also this information should actually be in the paper, as Maarten van Wesel already wrote, as the later reader should be also be made aware of this.

So, judging from your post, the only thing that you did wrong was not to note this in the paper itself (please add a comment to this post if this assumption is wrong). What then went wrong in the journal's workflow is that the paper was rejected due to copying rather than asking you to add such a note in the paper. A possible explanation is that checking for plagiarism is done by the publisher's office beforehand, and they actually never saw (or read) the cover letter.

I think that it is fair to write a letter to the editor, mentioning that (1) you already wrote in the cover letter that you submitted extended work, and (2) you are of course happy to add a note that this is an extended work of [Previous work].



On a related note, there may be a small copyright problem. You may have already given an exclusive licence to distribute your work to one publisher with your earlier paper. If you now copy a good part of that work, the new publisher may see this as problematic. While many publishing agreements nowadays explicitly allow reuse of the work in extended versions, not all of them do, so the new publisher's office may suspect that this is not the case for your earlier paper. Coincidentally, many extended versions of papers are actually completely rewritten, which circumvents this problem altogether. Whether an extended version should be a full rewrite is yet another discussion, which we probably don't want to pursue in this thread.