Q: Is it plagiarism if two studies use the same text in the methods section?
I will submit two articles comparing different materials with the same method. The materials and methods section is almost the same. Plagiarism detection software could not detect plagiarism, because the articles have not published yet. Will it be a problem if both of them are published in the future with the same materials and methods section in different journals ?
In general, copying text even from one of your own previously published articles without citing the source is a breach of publication ethics as this amounts to self-plagiarism. Similar to plagiarism of another person's work, self-plagiarism too, if detected after publication, could lead to retraction.
Studies to determine how much editors rely on plagiarism detection software show that they very rarely rely solely on plagiarism detection software to give a manuscript a verdict of plagiarism. Editors consider the software results but largely use their own judgement as well. These studies and general discussion forums inolving CrossCheck members indicate that editors tend to be more tolerant of textual similarities in the methods section, because most original studies use previously described methods.
However, the consensus is that it is still essential to cite the source article in which the methods were first described. This applies even to commonly used methods.
If you are submitting two manuscripts based on the same method, here's what you need to do to safeguard yourself against self-plagiarism:
1. Be sure that the studies are distinct enough to warrant two separate publications without being considered a case of salami slicing.
2. Ensure that both your manuscripts cite the original study that first described the said method (here, I assume that the method itself has not been devised by you and has been described previously).
3. Inform the editor in the cover letter that the content duplication in the methods section is intentional as you have replicated a previously published method.
4. If one manuscript gets published earlier than the other, the second manuscript should cite the first and indicate that the methods have been previously described in one of your own papers.
5. If both manuscripts are submitted around the same time, the cover letter for each should disclose that another study conducted using the same method is under consideration by another journal.
I hope this helps! Let me know if you have any other questions.