The Cochrane Collaboration takes measures to prevent, detect, and address plagiarised content in Cochrane Reviews. See Box 1 for a definition of plagiarism.
Box 1. Definition of plagiarism
“Plagiarism is the use of others' published and unpublished ideas or words (or other intellectual property) without attribution or permission, and presenting them as new and original rather than derived from an existing source. The intent and effect of plagiarism is to mislead the reader as to the contributions of the plagiarizer. This applies whether the ideas or words are taken from abstracts, research grant applications, Institutional Review Board applications, or unpublished or published manuscripts in any publication format (print or electronic).”
This policy relates to the Methodological Expectations of Cochrane Intervention Reviews (MECIR) reporting standard 22.
Special circumstances for Cochrane Systematic Reviews
There are special circumstances when similarity in text is expected in Cochrane Systematic Reviews by the nature of the type of work. These special circumstances may result in text similarity software, such as CrossCheck (Table 1), finding a high level of similarity of the Cochrane Review text with text from other article(s). High levels of similarity would not always be considered plagiarism.
Table 1. Special circumstances that will generate high levels of text similarity between Cochrane Systematic Reviews, versions of Cochrane Systematic Reviews, and other articles
Text similarity expected?
Similar methods sections
Yes, Cochrane Reviews can be expected to have a high percentage of overlap in the methods section because of standardized methods. This is unlikely to cause concern unless text is copied verbatim and without correct citation
Cochrane Review Group-specific template used for text in one or more sections
Yes, if an author uses a Cochrane Review Group template for one or more sections (e.g. background, methods), and states that a template has been used, a high percentage of overlap would be expected and should not cause concern
See ‘Use of text templates’ below for details
Protocol to review, review to update, etc.
Yes, a high percentage of overlap would be expected between certain sections of these versions (e.g. background, methods) and should not cause concern
Yes, a high percentage of overlap would be expected between certain sections of the protocol and the reviews that follow the protocol (e.g. background, methods). This should not cause concern, but it should be clear to the reader that the same text is used across a series of linked reviews
Split and merged reviews
Yes, some overlap would be expected between the different reviews. This should not cause concern, but it should be clear to the reader that the same text is used across a series of linked reviews
Similarities with published studies (e.g. trials described in the characteristics tables/risk of bias tables)
Yes, some overlap would be accepted here. Authors should follow the guidance (see ‘Avoiding plagiarism’) to avoid the possibility of plagiarism
Co-publication of a Cochrane Review (including Protocol and Updates) or republication in official Cochrane journals or derivative products
Yes, a high level of overlap would be expected. This should not cause concern as long as the co-publication was agreed according to the policy
A non-Cochrane systematic review is converted to a Cochrane Review
Yes, a high level of overlap may be expected. This should not cause concern as long as the co-publication was agreed according to the policy
A Cochrane Review is expected to be an original piece of academic work produced by the listed authors. Material copied from other sources may be used but should always be acknowledged. If direct quotes of more than a few words of original material are included, these should generally be indicated both by using quotation marks andby citing the source (citation alone is not enough). See examples in Table 2.
Table 2. Examples of correct citation
|Citing||The study was successful (Griffin 1990); it confirmed previous findings (Howes 1995).|
|Paraphrasing: using own words and making the source clear from the reference||It is the responsibility of systematic review authors to ensure the review conforms to Cochrane reporting guidelines including: declaring any potential conflicts of interest, that the review is free from plagiarised material and that all contributors are acknowledged (Wager 2011).|
|Using text verbatim||Wager and colleagues proposed that authors should “...ensure that contributors are properly acknowledged, that potential conflicts of interest are declared, and that the review does not contain plagiarized material” (Wager 2011).|
In Table 2, we state “It is the responsibility of systematic review authors to ensure the review conforms to Cochrane reporting guidelines including... (Wager 2011).” These are our own words, and the source is clear from the reference. If we wanted instead to use a sentence directly from the Wager paper, we would have had to do so by using quotation marks, constructing a different sentence citing the reference in brackets immediately afterwards. For example:
Wager and Wiffen proposed that authors should “...ensure that contributors are properly acknowledged, that potential conflicts of interest are declared, and that the review does not contain plagiarized material” (Wager 2011).
Citations should be placed as close as possible to the quotation or statement from the original source. For example, if a paragraph includes two quotations, the appropriate citation should be inserted immediately after the relevant quotation and not placed together at the end of the paragraph or section. See the Cochrane Style Manual for information about references and citing references in the text.
Cochrane Review Groups are encouraged to bring the plagiarism policy to the attention of authors early in the review development cycle, such as when authors propose a title for a Cochrane Review.
Use of text templates
As Cochrane Review Groups have evolved, there has been an increasing use of templates that ensure methods are clearly presented. However, the result is that reviews may include material that is similar or identical to that in other reviews, to an extent that might not be permissible in articles published in other journals. For example, reviews may use standard methods resulting in similar text and some Cochrane Review Groups encourage the use of standard introductory passages (e.g. to describe a condition or intervention).
Therefore, protocols and reviews that include template text should include a statement acknowledging the use of templates, such as “The background and methods section of this protocol/review is based on a standard template used by Cochrane [insert name] Review Group”. This statement may be appropriate to include in the ‘Acknowledgements’ section.
Cochrane Overviews of reviews (Cochrane Overviews)
“Cochrane Overviews of reviews (Cochrane Overviews) are Cochrane Reviews designed to compile evidence from multiple systematic reviews of interventions into one accessible and usable document” (see the Cochrane Handbook for Systematic Reviews of Intervention, Chapter 22). Authors may wish to reuse text from the original systematic reviews in a Cochrane Overview. In this circumstance, authors should follow the standard guidance to reference source material. A high percentage of overlap with other source content (e.g. a Cochrane Review) may occur, but will not cause concern if the text has been cited appropriately.