Submitting two related papers to two journals simultaneously [duplicate]

Question

I have spent 2+ years working on a project in computational neuroscience that has interest for clinicians and now I am starting to write the paper text. I want to submit it to one of neurology-related journals (and clinicians who I work with, support this). However as far as I understand, it does not make sense to include too much technical info / too much extra statistics in the journal for neurologists.

I have developed a pretty elaborate data analysis pipeline than can do many things, so I want also to publish other less-bold-sounding outcomes of my project in a journal for computational neuroscience or in a journal for biomed data analysis. I have seen many people doing something along these lines (though not among my immediate colleagues), but for me it is the first time. What worries is that I don't understand very well how to organize the second paper: should I include the main result, that I report in the neurological paper, in the second one, or just briefly mention it, citing the submitted paper / preprint?

So to summarize, I have two somewhat related questions:

1. is there somewhere any informal guideline on how to organize the second paper in relation to the first one?
2. I could either present the second part of the research as a "methods" paper (emphasizing the code I wrote, it can indeed be used by other people) or as a "new approach" paper (emphasizing the new approach that gives interesting results). I think both are important. How do I choose? Or should I write 3 papers instead of two?

Answer 1

Personally, I would advise against submitting these two papers simultaneously, precisely because you still seem to be (relatively) inexperienced in terms of getting papers published. You could quickly get into a number of tricky situations, for example:

(1) You submit both papers at the same time for different journals, but then you receive from both journals requests for revision that can cause conflicts or contradictions between both papers.

(2) One of the journals asks you to add crucial contents (like the full results of an analysis) that are heavily featured in the other paper, thus automatically converting both papers into forms of self-plagiarism.

Besides, it is not very advisable to put into one paper a citation for another paper that has not yet been published or peer-reviewed, especially if its results constitute an important background for the whole research.

Overall, I just don't see how your idea is going to lead to a positive outcome. There is just too much that can go wrong, so I would advise you to submit the most important paper first, do the necessary revisions, and then once it is accepted, use the revised result as a basis for preparing the second related paper. This will give you less headaches in the long run, and minimize the risks of having your papers retracted due to suspicions of self-plagiarism.

Note that depending on the journal/publisher, even 1/4 (or 1/5!) of similar text between papers can be enough to trigger accusations of self-plagiarism, so be careful to distinguish the papers as much as possible, even if they represent different branches of the same research.