Prevalence of plagiarism in hijacked journals: A text similarity analysis

Background: The study examines the prevalence of plagiarism in hijacked journals, a category of problematic journals that have proliferated over the past decade. Methods: A quasi-random sample of 936 papers published in 58 hijacked journals that provided free access to their archive as of June 2021 was selected for the analysis. The study utilizes Urkund (Ouriginal) software and manual verification to investigate plagiarism and finds a significant prevalence of plagiarism in hijacked journals. Results: Out of the analyzed sample papers, 618 (66%) were found to contain instances of plagiarism, and 28% of papers from the sample (n = 259) displayed text similarities of 25% or more. The analysis reveals that a majority of authors originate from developing and ex-Soviet countries, with limited affiliation ties to developed countries and scarce international cooperation in papers submitted to hijacked journals. The absence of rigorous publication requirements, peer review processes, and plagiarism checks in hijacked journals creates an environment where authors can publish texts with a significant amount of plagiarism. Conclusions: These findings suggest a tendency for fraudulent journals to attract authors who do not uphold scientific integrity principles. The legitimization of papers from hijacked journals in bibliographic databases, along with their citation, poses significant challenges to scientific integrity.