Q: How do I get a fair plagiarism check for systematic reviews?
You haven’t provided any details in your query. So, I am not sure whether your main concern is about avoiding plagiarism, hoping for a fair plagiarism check (using the tool or service of choice), or hoping for a fair response by the journal to perceived plagiarism. I will respond keeping these multiple aspects in mind.
Firstly, as a systematic review – no matter the type of review, whether quantitative, qualitative, or meta-analysis – is a detailed review of existing literature (answering a specific question), it entails writing the paper in your own words. If you do this diligently, this proves to be a plagiarism check of its own. However, I understand that in fulfilling all the criteria of the PRISMA checklist for systematic reviews, some authors may find that they are restricted in how much they can change. A good way to deal with plagiarism is to paraphrase, although paraphrasing can come with its own challenges. Here are a couple of resources that can help you with this. The first especially deals with paraphrasing.
If you are looking for external help in avoiding plagiarism in your paper, as you may know, several tools and services exist. One such popular tool is iThenticate. However, since a review paper will, for obvious reasons include some content from existing publications, it might be difficult for you to gauge what would be an acceptable percentage of similarity. Perhaps, a more reliable option would be a service (rather than a tool) as it also includes a human input (compared with the solely machine-based input of a tool). Editage provides a plagiarism check service, which you can find out more about here.
Finally, journal editors are mostly fair and reasonable. They do use plagiarism software themselves, but that is mainly for an initial check. They don’t rely solely on the tool; they also make an evaluation of their own. So, if you have been sincere and diligent in avoiding plagiarism, and fulfilled the other requirements of a systematic review, you shouldn’t have much reason to worry about a fair check. Good luck with the paper.