A chart showing happiness levels by country, generated from a meta-analysis (public domain).
“Meta-analysis refers to the application of quantitative methods to the problem of combining results from different analytic studies” [1].
But what happens when some misconduct occurs, and the same study is published twice?
According to a Choi, et al.,
“With the increasing use of meta-analysis, duplicate publication of original research is particularly problematic. Duplicate publication can result in an inappropriate weighting of the study results” [2].
Here [below] is a case of apparent duplicate publication that I was alerted to recently. Both articles appeared at about the same time — the end of 2013 or the beginning of 2014. Each article has six authors. Four authors are common to both articles, and each article also has two authors that only appear on that one article.
One might argue that this is not duplicate publication but plagiarism, because the authors are different.
The first article is “Sleep Organisation in Depression and Schizophrenia: Index of Endogenous Periodicity of Sleep as a State Marker:”
The first of two nearly identical articles.
The second article is “Polysomnographic Sleep Patterns in Depressive, Schizophrenic and Healthy Subjects:”
The second of two nearly identical articles.
Although the titles differ, the text in the two articles is mostly the same. As far as I know these two articles haven’t been used in any meta-analyses. Both are published open-access.
In cases like these, the publishers can be victims of the authors submitting papers to multiple journals at once. Plagiarism checks come up negative because the plagiarism database has not yet been populated with the article’s text.
I agree with Choi, et. al. and think that the increasing amount of duplicate publication/plagiarism may threaten the validity of meta-analyses. Because it is so easy to get published in predatory journals, they may contain more duplicated and plagiarized articles, compounding the problem.
[1]. Wachter, K. L. and Straf, M. L. (1990). Introduction. In: The future of meta-analysis. Wachter, K. L. and Straf, M. L. (Eds.). New York: Russell Sage Foundation, 1990. p. xiii.
[2]. Duplicate publication of articles used in meta-analysis in Korea. Whan-Seok Choi, Sang-Wook Song, Sun-Myeong Ock, Chul-Min Kim, JungBok Lee, Woo-Jin Chang, Se-Hong Kim. Springerplus. 2014; 3: 182. doi: 10.1186/2193-1801-3-182
